SOIL  FERTILITY 

AND  PERMANENT 

AGRICULTURE 


| 


jniversity  of 
Southern 
Library  F 


H! 


CYRIL  G.HOPKINS 


UNIVERSITY  OF  CALIFORNIA 
AT    LOS  ANGELES 


Fon 


COUNTRY  LIFE  EDUCATION 
SERIES 


Edited  by  Charles  William   Burkett,  recently  Director 

of  Experiment  Station,  Kansas  State  Agricultural 

College ;   Editor  of  American  Agriculturist 


TYPES  AND  BREEDS  OF  FARM  ANIMALS 
By  Charles  S.  Plumb,  Ohio  State  University 

PRINCIPLES  OF  BREEDING 

By  Eugene  Davenport,  University  of  Illinois 

FUNGOUS  DISEASES  OF  PLANTS 

By  Benjamin  Minge  Duggar,  Cornell  University 

SOIL  FERTILITY  AND  PERMANENT 
AGRICULTURE 

By  Cyril  George  Hopkins,  University  of  Illinois 

PRINCIPLES  AND  PRACTICE  OF  POULTRY 
CULTURE 

By  John  Henry  Robinson,  Editor  of  Farm-Poultry 

GARDEN  FARMING 

By  Lee  Cleveland  Corbett,  United  States  Depart- 
ment of  Agriculture 

Other  volumes  in  preparation 


SOIL  FERTILITY  AND 
PERMANENT  AGRICULTURE 


BY 

CYRIL  G.  HOPKINS,  PH.D. 

PROFESSOR    OF    AGRONOMY    IN    THE    UNIVERSITY    OF    ILLINOIS,    CHIEF    IN 

AGRONOMY    AND    CHEMISTRY    AND    VICE    DIRECTOR    OF    THE 

ILLINOIS    AGRICULTURAL   EXPERIMENT    STATION 


GINN  AND  COMPANY 

BOSTON  •  NEW  YORK  •  CHICAGO  •  LONDON 


PREFACE 

Liebig  said,  "Agriculture  is,  of  all  industrial  pursuits,  the  rich- 
est in  facts  and  the  poorest  in  their  comprehension."  To  a  large 
degree  this  statement  is  still  true,  and  the  chief  purpose  of  this 
volume  is  to  bring  together  in  convenient  form  the  world's  most 
essential  facts  gathered  from  the  field  and  laboratory,  and  to 
develop  from  them  some  foundation  principles  of  permanent 
agriculture ;  for,  as  Liebig  also  truly  said,  "  Facts  are  like  grains 
of  sand  which  are  moved  by  the  wind,  but  principles  are  these 
same  grains  cemented  into  rocks." 

While  one  dare  not  believe  that  error  has  been  completely 
avoided,  the  facts  presented  have  been  checked  with  all  reasonable 
care,  and  they  may  be  accepted  with  the  confidence  that  they  are 
accurately  reproduced  from  the  original  data. 

Unsolved  problems  still  remain,  and  some  conclusions  which 
seem  to  be  indicated  by  the  data  thus  far  reported  may  be  modi- 
fied later  when  more  complete  information  is  afforded.  The 
author  will  always  receive  with  deep  appreciation  suggested  ad- 
ditions, modifications,  or  corrections. 

It  is,  perhaps,  unnecessary  to  say  to  the  reader  that  his  general 
knowledge  of  farm  practice  is  presupposed,  and  no  attempt  has 
been  made  to  include  herein  a  thousand  details  with  which  every 
man  experienced  in  the  art  of  agriculture  already  is  familiar. 

For  the  sake  of  himself  and  children  it  must  be  said  to  the 
practical  farmer  that  he  should  encourage  the  teaching  of  the 
science  of  agriculture  in  the  school,  even  though  he  may  know 
much  more  than  the  teacher  concerning  the  art  of  agriculture. 


viii  PREFACE 

To  encourage  the  teacher,  let  me  say  that  much  of  the  science 
of  agriculture  can  be  successfully  taught  without  a  field  or  a  gar- 
den, and  even  without  complete  knowledge  of  the  art.  Thus,  you 
may  teach  why  clover  should  be  grown  and  when  it  contains  the 
most  nitrogen,  but  leave  the  farmer  to  determine  for  himself  when 
to  plow  it  under,  if  he  is  the  better  judge  of  seasonal  conditions 
and  of  their  probable  influence  upon  his  own  soil  and  crop. 

CYRIL  G.  HOPKINS 


NOTE.  Opportunity  has  been  taken  to  insert  in  this  edition  the  later  data 
from  some  of  the  most  important  long-continued  field  investigations.  In  addi- 
tion, a  list  of  questions  relating  to  the  most  important  facts  in  every  chapter 
has  been  prepared  for  the  convenience  of  the  teacher  in  helping  the  student 
to  acquire  a  thorough  knowledge  of  the  most  essential  facts  and  principles  of 
soil  fertility,  with  economy  of  time  and  with  conservation  of  mental  energy. 
These  questions  are  supplied  in  pamphlet  form  by  the  publishers.  —  C.  G.  H. 


CONTENTS 


PAGE 

INTRODUCTION xvii 

PART   I.     SCIENCE  AND   SOIL 

CHAPTER 

I.    FOUNDATION  FACTS  AND  PRINCIPLES i 

II.    THE  MORE  IMPORTANT  ELEMENTS  AND  COMPOUNDS  .        .        .12 

III.  PLANT  FOOD  AND  PLANT  GROWTH 26 

IV.  THE  EARTH'S  CRUST 46 

V.    SOIL  FORMATIONS  AND  CLASSIFICATIONS 54 

VI.    SOIL  COMPOSITION        .        .        . 58 

VII.    AVAILABLE  PLANT  FOOD 107 

VIII.    SOIL  SURVEYS  BY  THE  UNITED  STATES  BUREAU  OF  SOILS  .        .114 
IX.    SOIL  ANALYSES  BY  THE  UNITED  STATES  BUREAU  OF  SOILS        .  136 
»     X.    CROP    REQUIREMENTS  FOR    NITROGEN,   PHOSPHORUS,  AND   PO- 
TASSIUM        153 

XI.    SOURCES  OF  PLANT  FOOD 156 

PART   II.     SYSTEMS   OF   PERMANENT  AGRICULTURE 

XII.    LIMESTONE 160 

XIII.  PHOSPHORUS 183 

XIV.  ORGANIC  MATTER  AND  NITROGEN 194 

.     XV.    ROTATION  SYSTEMS  FOR  GRAIN  FARMING 226 

XVI.    LIVE-STOCK  FARMING 231 

XVII.    THE  USE  OF  PHOSPHORUS  IN  DIFFERENT  FORMS        .        .        .  ^236 

XVIII.    THEORIES  CONCERNING  SOIL  FERTILITY 300 

PART   III.     SOIL  INVESTIGATIONS   BY  CULTURE   EXPERIMENTS 

XIX.    THE  ROTHAMSTED  EXPERIMENTS 344 

XX.    PENNSYLVANIA  FIELD  EXPERIMENTS 420 

XXI.    OHIO  FIELD  EXPERIMENTS 441 

XXII.    ILLINOIS  FIELD  EXPERIMENTS 453 

XXIII.    FIELD    EXPERIMENTS    IN    THE    SOUTH,    INCLUDING    SOUTHERN 

ILLINOIS 476 

ix 


CONTENTS 


CHAPTER  PAGE 

XXIV,    MINNESOTA  SOIL  INVESTIGATIONS         ......  499 

XXV.    CANADIAN  FIELD  EXPERIMENTS 505 

XXVI.    SHORT-TIME   POT-CULTURE  AND  WATER-CULTURE  EXPERIMENTS 

IN  COMPARISON  WITH  FIELD  RESULTS 513 


PART  IV.     VARIOUS   FERTILITY   FACTORS 


XXVII. 

XXVIII. 

XXIX. 

XXX. 

XXXI. 

XXXII. 

XXXIII. 

XXXIV. 

XXXV. 

XXXVI. 

XXXVII. 

XXXVIII. 

XXXIX. 


MANUFACTURED  COMMERCIAL  FERTILIZERS  .... 
CROP  STIMULANTS  AND  PROTECTIVE  AGENTS 

CRITICAL  PERIODS  IN  PLANT  LIKE 

FARM  MANURE 

LOSSES  OF  PLANT  FOOD  FROM  PLANTS        .... 

LOSSES  OF  PLANT  FOOD  FROM  SOILS 

FIXATION  OF  PLANT  FOOD  BY  SOILS 

ANALYZING  AND  TESTING  SOILS 

RELATION  OF  FERTILITY  TO  APPEARANCE  OF  SOILS  OR  CROPS 

FACTORS  IN  CROP  PRODUCTION 

ESSENTIAL  FACTORS  OF  SUCCESS  IN  FARMING 

THE  VALUE  OF  LAND 

Two  PERIODS  IN  AGRICULTURAL  HISTORY  . 


APPENDIX 

SECTION 

1.  THE  PRODUCTION  OF  PHOSPHATE  ROCK        .        .        .        .     '  . 

II.  MODEL  FERTILIZER  LAW 

III.  COMPOSITION  OF  ANIMAL  AND  PLANT  PRODUCTS 

IV.  STATISTICS  OF  AGRICULTURAL  PRODUCTS 

V.  METHODS  OF  SOIL  ANALYSIS 

VI.    COMPOSITION  OF  SOME  EUROPEAN  SOILS 

VII.    AGRICULTURAL  COLLEGES  AND  EXPERIMENT  STATIONS  IN  THE  UNITED 
STATES  AND  CANADA 


5'7 
533 
538 
S4i 
549 
556 
562 

565 
572 
575 
584 
586 

590 


595 
599 
602 
605 
626 
634 

643 


INDEX 647 


LIST   OF   TABLES 

TABLE  PAGE 

1.  Elements,  Symbols,  and  Atomic  Weights 10 

2.  The  More  Important  Elements  :  Occurrence 13 

3.  Composition  of  Silicates 48 

4.  Composition  of  Rock 49 

5.  Composition  of  Fresh  Limestone  and  Residual  Clay         .         .  51 

6.  Soils:  General  Groups    .         .         .         .         .         .         .         .         -55 

7.  Recognized  Soil  Types 56 

8.  Relative  "  Supply  and  Demand  "  of  Seven  Elements        ...  59 

9.  Composition  of  Productive  and  Nonproductive  Soils         ...  63 

10.  Composition  of  Adobe  and  Coral  Limestone  Soils   .  65 

1 1 .  Composition  of  Loess  Deposits        .......  69 

12.  Composition  of  Ten  Residual  Soils           ......  73 

13.  Mineral  Plant  Food  in  Wheat,  Corn,  Oats,  and  Clover    ...  75 

14.  Composition  of  New  York  Soils 75 

15.  Fertility  in  Illinois  Soils  :  Surface 82 

16.  Fertility  in  Illinois  Soils  :  Subsurface 84 

17.  Fertility  in  Illinois  Soils:  Subsoil    .......  86 

18.  Composition  of  Southern  Indiana  Surface  Soils        ....  88 
18.1.    Plant  Food  in  Surface  Soils  of  Iowa      ......  91 

19.  Composition  of  Surface  Soils  of  Tennessee      .....  93 

19.1.  Composition  of  Georgia  Soil          .......  94 

19.2.  Average  Composition  of  Some  Texas  Soils 95 

19.3.  Composition  of  Some  Louisiana  Soils 96 

20.  Composition  of  Some  Michigan  Soils 98 

10. i.  Composition  of  Canadian  Soils 103 

20. 2.  Certain  Plant-food  Elements  in  Illinois  Surface  Soils    .         .         .     105 

21.  Annually  Available  Fertility  in  Illinois  Soils    .         .         .         .         .110 

22.  Composition  of  Various  Extensive  Soil  Types  of  the  United  States       138 

23.  Fertility  in  Farm  Produce        .         .         .         .         .         .         .         .154 

24.  Fertility  in  Manure,  Rough  Feeds,  and  Fertilizers    .         .         .         .     157 

25.  Pennsylvania  Experiments  with  Lime      .         .         .         ...         .165 

25.1.    Maryland  Experiments  with  Lime          .         .         .         .         .         .167 

26.  Experiments  with  Magnesium  Carbonate          .         .         .         •  171 

27.  Losses  of  Calcium  Carbonate  from  Broadbalk  Field          .         .         .     174 

28.  Losses  of  Calcium  Carbonate  from  Hoos  Field         ....     175 

29.  Digestibility  of  Common  Food  Stuffs 199 


xii  LIST   OF  TABLES 

TABLE  PAGE 

30.  Plant  Food  recovered  from  Food  Consumed  (Illinois)     .         .         .201 

31.  Plant  Food  recovered  from  Food  Consumed  (Pennsylvania)   .         .  202 

32.  Plant  Food  recovered  from  Six  Months'  Feeding  (Ohio)         .         .  204 

33.  Fixation  of  Nitrogen  by  Alfalfa 214 

34.  Nitrogen  in  Sweet  Clover 220 

35.  Composition  of  Crimson  Clover 221 

36.  Composition  of  Legumes  and  Other  Plants      .         .         .                 .  222 

37.  38,  39,  and  39^.    Comparison  of  Raw  Phosphate  and  Acid  Phosphate 

247-253 

40.  Ohio  Experiments  with  Manure,  Phosphate,  Kainit,  Gypsum,  and 

Complete  Fertilizers     .         . 256 

41.  Balance  Sheet  for  Nitrogen  and  Phosphorus  in  Manure-phosphate 

Experiments .         .     257 

42.  Maryland  Experiments  with  Different  Phosphates    ...        .        .     262 

43.  Pennsylvania  Experiments  with  Different  Phosphates      .        '.         .     264 

44.  45,  44C,  and  45^.     Rhode  Island  Experiments  with  Nine  Phosphates 

268-274 

46  and  47.    Maine  Experiments  with  Different  Phosphates     .         .      276,  277 
48  and  49.    Massachusetts  Experiments  with  Different  Phosphates       279,  282 

50.  Illinois  Experiments  with  Raw  Rock  Phosphate       .         .  .     285 

51.  Steamed  Bone  Meal  and  Raw  Rock  Phosphate        ....     287 

52-58.   Rotation  Crops  on  Agdell  Field 346-352 

59.    Summary  of  Crop  Yields  and  Values,  Agdell  Field  .         .        .         .     360 
6oand6i.   Wheat  Yields,  Broadbalk  Field,  Averages    .         .         .      364,365 

62.  Wheat  Yields  at  Rothamsted,  Comparisons     ....      372,  373 

63.  Wheat  Yields,  Broadbalk  Field,  Nitrogen  Increments      .        .         .     374' 

64.  Wheat  Yields  at  Rothamsted,  Summaries 375 

65.  Rothamsted  Records,  Rainfall  and  Drainage   .....     377 
66  and  67.   Barley  Yields  on  Hoos  Field 380,  381 

68.  Potato  Yields  on  Hoos  Field 386,  387 

69.  Residual  Effect  of  Fertilizers  on  Hoos  Field    .         .         .        .         .     390 

70.  Hay  Yields  on  The  Park  at  Rothamsted 393 

71.  Root  Crops  on  Barn  Field 399,400 

72.  Rothamsted  Fields  abandoned  to  Nature 404 

73.  Plant  Food  in  Soil  of  Broadbalk  Plots .411 

74.  Composition  of  Drainage  Waters  from  Broadbalk  Field  .         .         .     413 

75.  Nitrogen  in  Soil  of  Agdell  Plots      .         .         .         .         .         .         .     416 

76.  Composition  of  Crops  grown  on  Agdell  Field 417 

77.  Composition  of  Hay  from  The  Park,  Rothamsted     .         .         .         .418 

78.  Pennsylvania  Crop  Yields  in  Field  Experiments       .         .       '.         .     423 
79  and  80.   Pennsylvania  Experiments  by  Twelve-year  Periods       .      428,  429 
81.  Pennsylvania  Experiments  :  Financial  Summary     ....     431 
8iP.    Pennsylvania  Experiments  :  Twenty-five-year  Average  .        .         .     434 


LIST   OF  TABLES  xiii 


82.  Ohio  Experiments :  Five-year  Rotation         .  .  442 

83.  Ohio  Experiments  :  Potatoes,  Wheat,  Clover         ....    448 

84.  Experiments  at  Strongsville,  Ohio 452 

85.  Illinois  Experiment  Plots,  Urbana 457 

86.  Comparable  Corn  Yields,  Illinois  Experiments       ....     459 

87.  Crop  Yields  on  Sibley  Field,  Illinois 462 

88.  Crop  Yields  on  Bloomington  Field,  Illinois    .....     464 

89.  Crop  Yields  on  Antioch  Field,  Illinois 467 

90.  Crop  Yields  on  Sand  Land,  Illinois        ......     468 

91.  Corn  Yields  on  Deep  Peat  Soil,  Illinois          .         ...         .         .     471 

92  and  93.    Corn  Yields  on  Peaty  Alkali  Soil,  Illinois  .         .         .      473,  475 

94.  Crop  Yields  in  Southern  Illinois,  Odin  Field          ....     478 

95.  Crop  Yields  in  Southern  Illinois,  Du  Bois  Field     .         .         .         .481 
96  and  97.    Crop  Yields  on  Worn  Hill  Land,  Vienna,  Illinois        .      483,  485 
98  and  98.1.    Pot-culture  Experiments  with  Worn  Hill  Soil .         .      486,  487 
99.    Southern  Iowa  Field  Experiments          ......     488 

loo.  Georgia  Fertilizer  Experiments  with  Corn  .....  490 
lor.  Rainfall  Records  at  Experiment,  Georgia  .....  491 
102  and  103.  Georgia  Fertilizer  Experiments  with  Cotton  .  .  492,  493 

104.  Alabama  Field  Experiments  with  Cotton        .....     495 
104.1.    Louisiana  Field  Experiments       .......     496 

105.  Minnesota  Soil  Investigations 499 

1 06  and  107.    Canadian  Field  Experiments 508,511 

108  and  109.    Comparison  of  Pot  Cultures  and  Field  Experiments.      513,  514 

no.    Composition  of  Farm  Manures 543 

nr.   Composition  of  Pulverized  Dried  Manures 545 

112.  Composition  of  Manure  before  and  after  Exposure          .         .         .     547 

113.  Composition  of  Bean  Crop  at  Different  Periods  of  Growth      .         .     550 

114.  Composition  of  Barley  at  Different  Periods  of  Growth    .         .         .     552 

115.  Plant  Food  removed  from  Plants  by  Leaching        ....     555 

116.  Nitrogen  in  Rothamsted  Drainage  Waters     .....     557 

117.  Soluble  Nitrogen  in  Cropped  Soils,  Rothamsted     ....     558 

1 1 8.  Ammonia  Fixation  and  Nitrification 563 

119.  Effect  of  Soil  Preparation,  Cultivation,  Irrigation,  and  Fertilization 

on  the  Yield  of  Corn .578 

1 20.  Value  of  Land,  measured  by  Crop  Yields 587 

121.  Composition  of  Animal  and  Plant  Products 602 


ILLUSTRATIONS 

PAGE 

GLACIAL  MAP  OF  NORTH  AMERICA 68 

GENERAL  SURVEY  SOIL  MAP  OF  ILLINOIS 76 

A  MAN  OF  SCIENCE:    EUGENE  WOLDEMAR  HILGARD 102 

MAP  OF  UNITED  STATES  SOIL  PROVINCES 116 

NITROGEN  FIXATION  BY  CLOVER 218 

TOPOGRAPHIC  MAP  OF  OHIO  EXPERIMENT  FIELD 252 

DIRECTOR  CHARLES  E.  THORNE 254 

SIR  JOHN  BENNET  LAWES 342 

SIR  JOSEPH  HENRY  GILBERT 344 

TURNIPS  ON  AGDELL  FIELD,  1908 362 

DIRECTOR  A.  D.  HALL 408 

DIRECTOR  EDWARD  B.  VOORHEES 517 

RAINFALL  CHART  OF  NORTH  PLATTE,  NEBRASKA    ......  580 

RAINFALL  MAP  OF  THE  UNITED  STATES 582 


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INTRODUCTION 

IT  is  the  first  business  of  every  farmer  to  reduce  the  fertility  of 
the  soil,  by  removing  the  largest  crops  of  which  the  soil  is  capable; 
but  ultimate  failure  results  for  the  landowner  unless  provision 
is  made  for  restoring  and  maintaining  productiveness.  Every 
landowner  should  adopt  for  his  land  a  system  of  farming  that  is 
permanent, —  a  system  under  which  the  land  becomes  better 
rather  than  poorer. 

If  the  independent  farmer  is  to  adopt  and  maintain  permanent 
systems  of  profitable  agriculture,  he  cannot  accept  "  parrot  " 
instruction ;  he  must  know  the  why  and  wherefore,  the  reason  for 
doing  things,  and  the  ultimate  effect  of  his  agricultural  practice 
upon  the  productive  power  of  the  land.  Every  farm  is  an  inde- 
pendent enterprise  in  which  the  farmer  himself  is  the  superin- 
tendent and  general  manager,  and  he  must  be  able  to  direct  the 
business,  even  though  he  may  be  the  only  man  to  execute  his 
own  plans.  The  agriculture  of  a  state  cannot  be  managed  from  a 
central  office.  The  landowner  must  think  for  the  land. 

The  author  is  familiar  with  the  often  expressed  idea  that  what 
the  farmer  wants  is  a  simple  statement  of  facts,  but  he  is  even 
more  familiar  with  the  absolute  truth  that  what  the  farmer  de- 
mands is  the  most  positive  proof  of  the  correctness  of  such  state- 
ment before  he  is  willing  to  make  any  change  from  a  practice 
based  upon  long  experience. 

In  the  preparation  of  this  book  free  use  has  been  made  of  such 
technical  terms  as  are  necessary  to  the  discussion  of  fundamental 
principles  with  scientific  correctness.  No  apology  is  offered  for 
this.  Farmers  and  agricultural  students  have  at  least  as  good 
intellects  as  other  classes  of  people;  and  if  when  they  leave  the 
farm  they  can  learn  to  understand  and  manage  successfully  such 
lines  of  business  as  banking,  contracting,  building,  operating 
railroads,  factories,  and  other  commercial  establishments,  — 

xvii 


xviii  INTRODUCTION 

which  they  are  doing  everywhere, —  they  can  also  understand  their 
own  business,  if  they  will,  when  they  remain  on  the  farm  or  in 
control  of  land. 

Technical  books  are  to  be  studied;  they  are  not  written  for  en- 
tertainment. They  furnish  definite  facts,  accurate  data,  and 
necessary  information,  relating  to  underlying  principles  upon  which 
permanent  successful  practice  must  be  based. 

The  most  important  material  problem  of  the  United  States  is  to 
maintain  the  fertility  of  the  soil,  and  no  extensive  agricultural 
country  has  ever  solved  this  problem.  The  frequent  periods  of 
famine  and  starvation  in  the  great  agricultural  countries  of  China, 
India,  and  Russia,  and  the  depleted  lands  and  abandoned  farms 
of  our  own  eastern  United  States  are  facts  that  serve  as  a  constant 
proof  that  the  common  practice  of  agriculture  reduces  the  produc- 
tive power  of  land. 

I  The  rule  is  almost  universal  that  old  land  is  less  productive  than 
new  land.  This  simple  and  well-recognized  fact  points  inevitably 
toward  future  poverty,  not  only  for  the  individual  or  the  family, 
but  likewise  for  the  commonwealth  and  for  the  nation.  We  may 
ignore  this  if  we  choose  in  America  for  a  few  more  years,  but  with 
the  decreasing  productive  power  of  our  lands  and  with  a  rapidly 
increasing  'population  the  truth  must  strike  us  in  the  face  in  the 
near  future. 

/  We  cannot  afford  to  let  ignorance,  prejudice,  or  bigotry  blind  us 
in  this  matter,  neither  in  ourselves  nor  in  others.  Even  the  confi- 
dent assurance,  by  those  who  live  in  continued  plenty,  that  the 
people  of  earth  are  not  destined  to  suffer  hunger,  does  not  remove 
the  positive  fact  that  thousands,  and  sometimes  millions,  of  people 
actually  die  of  starvation  within  a  single  yearlin  some  of  the  old 
agricultural  countries. 

An  early  recognition  of  these  world-wide  conditions  and  tend- 
encies is  of  paramount  importance  to  the  people  controlling  the 
more  productive  lands  of  the  United  States,  not  only  for  their  own 
sake,  but  also  for  the  sake  of  others  who  are  dependent  upon  those 
lands  for  their  present  and  future  support,  whether  engaged  directly 
in  agricultural  pursuits  or  in  other  industrial  or  professional  lines, 
which  cannot  exist  and  prosper  without  agriculture. 

If  the  art  of  agriculture  has  ruined  land,  the  science  of  agricul- 


INTRODUCTION  xix 

ture  must  restore  it;  and  the  restoration  must  begin  while  some 
farmers  are  still  prosperous,  for  poverty-stricken  people  are  at 
once  helpless  and  soon  ignorant.  Outside  help  will  always  be 
required  to  redeem  impoverished  soils,  for  poverty  makes  no  in- 
vestments, and  some  initial  investment  is  always  required  for  soil 
improvement. 

It  is  the  purpose  of  this  book  to  teach  the  science  of  soil  fertility 
and  permanent  agriculture,  chiefly  by  reporting  facts  rather  than 
by  offering  theories;  and  any  one  of  common  sense  who  reads  the 
English  language,  and  who  can  understand  the  common  school 
arithmetic,  can  understand  this  book  if  he  will  study  it.  (The 
fact  may  well  be  recognized  that  some  who  have  ample  time  for 
study,  though  physically  industrious,  are  mentally  lazy.1) 

The  author  suggests,  however,  that  the  busy  farmer,  who 
wishes  to  familiarize  himself  as  quickly  as  possible  with  the  most 
essential  practical  facts  pertaining  to  the  economical  and  perma- 
nent improvement  of  common  or  normal  soils,  and  who  is  willing 
to  pass  over  temporarily  the  discussion  of  foundation  principles, 
may  well  begin  the  study  of  this  book  with  "  Systems  of  Perma- 
nent Agriculture,"  Part  II,  after  first  making  the  following  facts 
a  part  of  his  ever  ready  knowledge: 

(1)  Phosphorus  and  decaying  organic  matter  are  the  two  sub- 
stances which  constitute  the  key  to  profitable  systems  of  permanent 
agriculture  on  most  of  the  normal  soils  of  America  ;  although, 
when  soils  become  sour,  or  acid,  ground  natural  limestone  should 
also  be  regularly  applied,  at  the  rate  of  about  two  tons  per  acre 
every  four  to  six  years. 

(2)  There  are  six  essential  positive  factors  in  crop  production: 
the  seed,  a  home  for  the  plant,  the  food  of  which  the  plant  is  made 
(and  this  factor  is  just  as  important  for  plants  as  it  is  for  animals) , 
moisture,  heat,  and  light.     Of  these  six  factors,  the  least  appre- 
ciated and  the  most  neglected  is  that  of  plant  food,  and  yet  this 
is  a  factor  which  the  farmer  can  very  largely  control,  whereas  the 
others   (except   the  seed)   are    largely  beyond  his  control.    (An 
important  negative  factor  is  protection  from  weeds,  insects,  and 
disease.) 

1 "  Many  poor  farmers  have  a  lazy  faith  in  the  Lord ;  they  think  or  hope  that 
He  will  somehow  make  up  for  whatever  they  fail  to  do."  — HOARD. 


XX  INTRODUCTION 

(3)  Of  the  ten  different  chemical  elements  absolutely  required 
for  the  growth  of  every  agricultural  plant,  three  come  directly  from 
air  and  water  in  practically  unlimited  amounts,  and  these  three 
(carbon  and  oxygen  from  air  and  hydrogen  from  water)  constitute 
about  95  per  cent  of  the  common  mature  crops.   Nevertheless,  each 
one  of  the  seven  elements  obtained  from  the  soil,  though  aggre- 
gating only  5  per  cent,  is  absolutely  necessary  to  the  life  and  full 
development  of  the  plant.    Indeed,  if  any  one  of  these  elements 
be  entirely  lacking,  the  soil  would  be  infertile  and  barren.    So 
important  are  these  plant-food  elements,  that  soils  are  found  so 
deficient  in  some  essential  plant  food  that  the  addition  of  a  single 
element  will  more  than  double  the  crop  yield. 

(4)  The  five  elements,  potassium,  magnesium,  calcium,  iron,  and 
sulfur,  are  contained  in  most  normal  soils  in  such  large  amounts, 
compared  to  the  requirements  of  crops,  that  the  supply  rarely 
becomes  depleted.  Thus,  in  most  cases,  the  problem  is  narrowed 
to  the  two   elements,   nitrogen   and   phosphorus,   although,  for 
various  reasons,  potassium  also  has  come  to  have  a  recognized 
money  value  in  commercial  fertilizers. 

(5)  Nitrogen  is  contained  in  the  air  in  inexhaustible  amount, 
but  the  legumes  (clover,  alfalfa,  peas,  beans,  etc.)  are  the  only 
agricultural  plants  which  have  power  to  utilize  the  free  nitrogen  of 
the  air.   Nitrogen  in  limited  amount  is  contained  in  the  soil  in  the 
organic  matter,  the  principal  material  which  gives  a  good  soil  its 
dark  color.    If  the  supply  of  organic  matter  is  maintained,  by 
plowing  under  farm  manure,   clover,   cowpeas,   or  other  green 
manures,  then  the  supply  of  nitrogen  will  also  be  maintained. 

(6)  The  plowed  soil  of  an  acre  (2  million  pounds,  for  a  depth  of 
6|  inches)  of  rich,  well-balanced  normal  land  in  the  Corn  Belt 
contains  about  8000  pounds  of  nitrogen,  2000  pounds  of  phosphorus, 
35,000  pounds  of  potassium,  and  15  tons  of  calcium  carbonate 
(limestone) . 

(7)  The  surface  soils  of  the  United  States  vary  in  composition: 
(a)   in  nitrogen  content,  from   1000-  pounds  to  35,000  pounds; 
(6)  in  phosphorus  content,  from  160  pounds  to  15,000  pounds; 
(c)  in  potassium  content  from   3000  pounds  to   60,000  pounds, 
per  acre;  and  many  soils  not  only  contain  no  lime,  but  are  markedly 
acid  and  thus  require  heavy  applications  of  lime,  while  some  pro- 


INTRODUCTION  xxi 

ductive  soils  contain  as  much  as  20  per  cent  of  calcium  carbonate, 
corresponding  to  200  tons  of  limestone  per  acre. 

(8)  A  zoo-bushel  crop  of  corn  takes  from  the  soil  about  100 
pounds  of  nitrogen,  17  pounds  of  phosphorus,  and  19  pounds  of 
potassium,  in  the  grain,  and  about  48,  6,  and  52  pounds  of  these 
respective  elements  in  the  stalks  or  stover. 

(9)  One  ton  of  average  fresh  farm  manure  contains  about  10 
pounds  of  nitrogen,  2  pounds  of  phosphorus,  and  8  pounds  of 
potassium;    and  100  pounds  of  the  most  common  "  complete  " 
commercial  fertilizer  contains  about  2  pounds  of  nitrogen,  4  pounds 
of  phosphorus,  and  2  pounds  of  potassium. 

(10)  One  ton  of  clover  hay  contains  about  40  pounds  of  nitro- 
gen, 5  pounds  of  phosphorus,  and  30  pounds  of  potassium.    When 
grown  on  soil  of  fair  productive  capacity,  the  roots  and  stubble 
of  the  clover  plant  contain  no  more  nitrogen  than  the  soil  has 
furnished  to  the  plant;   but  for  each  ton  of  clover  plowed  under, 
the  soil  is  enriched  by  about  40  pounds  of  nitrogen. 

(u)  Roughly  estimated,  the  plant  food  liberated  from  an  aver- 
age soil  during  an  average  season  with  average  farming  is  equiva- 
lent to  about  2  per  cent  of  the  nitrogen,  i  per  cent  of  the  phos- 
phorus, and  ^  of  i  per  cent  of  the  potassium,  contained  in  the 
surface  stratum  (about  6f  acre  inches,  or  2  million  pounds  of 
average  soil). 

(12)  As  an  average  in  live-stock  farming,  the  animals  retain  about 
one  fourth  of  the  nitrogen  and  phosphorus  and  destroy  two  thirds 
of  the  organic  matter  of  the  food  consumed,  and  large  loss  is  likely 
to  occur  in  the  manure  produced,  especially  in  nitrogen  and  or- 
ganic matter,  a  loss  of  one  half  of  these  constituents  being  easily 
possible  during  three  or  four  months,  in  part  from  fermentation, 
which  may  occur  even  under  cover,  and  in  part  from  leaching 
where  the  manure  is  exposed  to  the  weather  or  where  too  little 
absorbent  bedding  is  used. 

(13)  It  is  less  difficult  to  maintain  or  increase  the  organic  matter 
of  the  soil  by  means  of  legume  crops  and  crop  residues  in  a  good 
rotation  for  grain  farming  than  in  any  system  of  live-stock  farming 
which  does  not  include  the  purchase  of  feed. 

(14)  Some  satisfactory  rotation  plans  for  grain  farmers  are 
wheat,  corn,  oats,  and  clover  ;  or  wheat,  corn,  and  cowpeas  ;  or 


xxn  INTRODUCTION 

cotton,  corn,  and  oats  and  cowpeas.  The  first  of  these  is  a  four- 
year  rotation  which  should  include  a  catch  crop  of  clover  seeded 
the  first  year  and  plowed  under  for  corn  as  late  as  practicable  in 
the  spring  of  the  second  year.  The  other  two  are  three-year 
rotations,  and  they  should  also  include  legume  catch  crops  wherever 
practicable.  In  each  rotation  for  grain  farming,  all  products  are 
to  be  returned  to  the  soil  excepting  the  grain,  or  seed,  and  the  cotton 
lint.  Either  the  whole  cotton  seed  or  the  hulls  and  meal  should 
also  be  returned  for  fertilizer. 

(15)  In  live-stock  farming  the  feeding  should  be  done  on  the 
fields  so  far  as  practicable,  and  manure  produced  in  the  barn  should 
be  hauled  and  spread  in  the  fresh  condition  so  far  as  possible. 
Sufficient  bedding  should  be  used  to  absorb  all  of  the  liquid  excre- 
ment, which  is  as  valuable,  ton  for  ton,  as  the  solid  excrement. 

(16)  To  insure  the  maintenance  of  the  phosphorus  content  of 
the  soil  where  large  crops  are  produced,  about  20  pounds  of  phos- 
phorus per  acre  for  each  year  in  the  rotation  should  be  applied  in 
grain  farming  and  about  10  pounds  per  acre  in  live-stock  farming 
(aside  from  that  returned  in  the  manure).   To  enrich  the  soil  in 
phosphorus,  heavier  applications  should  be  made  for  a  time. 

(17)  The  average  investment  required  for  25  pounds  of  phos- 
phorus is  about  75  cents  in  200  pounds  of  fine-ground  natural 
rock  phosphate  of  good  grade,  about  $2.50  in  200  pounds  of  good 
steamed  bone  meal,  about  $3.00  in  400  pounds  of  good  acid  phos- 
phate, about  $6.00  in  600  pounds  of  the  average  "  complete  " 
commercial  fertilizer,  and  about  $80  in  manure  made  from  corn 
costing  40  cents  a  bushel.   The  natural  phosphate,  if  ground  to 
pass  through  a  sieve  with  10,000  meshes  to  the  square  inch,  gives 
satisfactory  results  when  applied  in  liberal  amounts  (as  1000  pounds 
per  acre  every  three  or  four  years),  if  used  in  connection  with 
decaying  organic  matter  in  sufficient  amount  to  maintain  the 
nitrogen. 

(18)  Potassium  salts  are  used  with  very  great  profit  on  soils 
positively  deficient  in  that  element,  as  on  most  well-drained  ex- 
tensive peaty  swamp  lands;    and  soluble  salts,  such  as  kainit, 
may  produce  some  profit  for  a  time  if  used  in  connection  with 
phosphorus  on  soils  deficient  in  decaying  organic  matter,  even 
where  the  total  supply  of  potassium  in  the  soil  is  very  large. 


INTRODUCTION  xxili 

(19)  Commercial  nitrogen  can  usually  be  used   with  profit  in 
market  gardening,  in  cotton  growing,  and  sometimes  in  the  pro- 
duction of  timothy  hay  near  large  cities;   or,  as  a  rule,  wherever 
the  gross  returns  from  an  acre  of  produce  exceeds  $50  or  $75. 

(20)  As  a  rule,  commercial  nitrogen  cannot  be  used  with  profit 
for  the  production  of  the  staple  grain  crops,  such  as  corn  and  wheat, 
although  under  some  conditions  small  applications  of  nitrogen 
alone  or  with  other  elements,  as  in  the  ordinary  so-called  "  com- 
plete "  fertilizer,  may  stimulate  the  plants  sufficiently  to  enable 
them  to  draw  more  heavily  upon  the  soil,  and  thus  return  apparent 
temporary  profit  in  a  system  of  ultimate  land  ruin. 

And  other  seed  fell  on  good  ground,  and  sprang  up,  and  bare  fruit  an  hundred 
fold.  —  JESUS. 

I  applied  mine  heart  to  know,  and  to  search,  and  to  seek  out  wisdom,  and  the 
reason  of  things.  —  SOLOMON. 

Every  man  shall  receive  his  own  reward  according  to  his  own  labor ;  for  we  are 
laborers  together  with  God.  —  PAUL. 


SOIL  FERTILITY  AND 
PERMANENT  AGRICULTURE 

PART    I  ,  , 
SCIENCE   AND   SOIL 

2-S  ' 


CHAPTER   I 

FOUNDATION  FACTS  AND  PRINCIPLES 

Science.  Science  means  knowledge,  nothing  more  and  nothing 
less.  It  does  not  mean  theory  unsupported  by  fact.  To  plow 
the  land  and  plant  the  seed  and  cultivate  the  crop  is  art,  or  prac- 
tice. To  know  what  the  soil  and  air  contain  and  what  the  crop 
requires  is  science.  If  10  cents  are  taken  from  70  cents,  only  60 
cents  remain.  This  is  science,  knowledge,  fact,  and  not  mere 
opinion.  In  the  study  of  soil  fertility  we  must  make  large  use  of 
two  well-established  exact  sciences,  mathematics  and  chemistry. 
Several  other  sciences  furnish  much  exact  data,  but  in  some 
branches  the  data  thus  far  secured  are  not  sufficient  to  fully  reveal 
the  controlling  facts  and  principles. 

Chemistry.  Chemistry  is  the  science  which  deals  with  the  com- 
position of  matter.  All  material  things  are  composed  of  about 
eighty  primary  substances,  called  elements,  which  may  exist  sepa- 
rately or  in  various  combinations,  called  compounds.  About  forty 
of  the  elements  are  more  or  less  common,  the  others  being  rare 
elements.  Air  and  soil  and  plants  and  animals  contain  less  than 
twenty  elements  that  are  of  interest  to  agriculture;  while  only 
ten  different  elements  are  known  to  be  essential  for  the  making  of 
agricultural  plants.  (One  other  element,  chlorin,  may  be  essen- 
tial, but,  if  so,  only  in  minute  quantity.) 


2  SCIENCE   AND    SOIL 

Chemical  elements.  An  element  is  a  substance  which  cannot  be 
divided  into  two  or  more  different  substances.  Sulfur  (S)  is  a 
solid,  nonmetallic  element,  easily  melted  to  the  liquid  form. 
A  piece  of  sulfur  may  be  divided  into  two  parts,  but  each  part  is 
sulfur,  and  if  nothing  else  is  added  to  sulfur,  nothing  but  sulfur 
can  be  obtained  from  it.  Carbon  (C)  is  the  principal  element  con- 
tained in  coal.  Iron  is  a  well-known  metallic  element.  Oxygen  (O) 
is  an  element  contained  in  the  air  in  the  gas  form. 

Chemical  compounds.  A[  compound  is  a  substance  which  con- 
tains two  or  more  different  elements  and  which  possesses  some 
properties  or  characteristics  not  possessed  by  either  element 
alone.  Thus,  if  carbon  and  sulfur  be  mixed  together  at  the  ordi- 
nary temperature,  the  product  is  only  a  mixture  in  which  each 
element  retains  its  own  properties;  but,  at  a  higher  temperature 
and  under  proper  conditions,  one  combining  weight  of  black 
carbon  will  unite  with  two  combining  weights  of  yellow  sulfur 
and  form  the  compound  called  carbon  disulfid  (CS2),  which  is 
neither  black  nor  yellow  nor  solid,  but  a  colorless  liquid  somewhat 
resembling  water,  but  which,  when  pure,  contains  absolutely  noth- 
ing but  the  two  elements,  carbon  and  sulfur. 

Carbon,  in  charcoal  for  example,  may  be  eaten  in  considerable 
quantity  without  harm,  and  sulfur  is  not  dangerous  in  large  doses; 
but  the  compound,  carbon  disulfid,  is  a  deadly  poison,  and  is  fre- 
quently used  as  an  insecticide  and  for  the  extermination  of  gophers 
and  other  burrowing  animals.  Thus  the  properties  of  the  com- 
pound may  differ  in  many  respects  from  those  of  either  element 
contained  in  it. 

On  the  other  hand,  when  carbon  is  burned,  by  uniting  with  the 
oxygen  of  the  air,  the  compound,  carbon  dioxid  (CO2),  is  formed, 
and  when  sulfur  is  likewise  burned,  the  compound,  sulfur  dioxid 
(SO2),  is  formed;  while  if  carbon  disulfid  is  burned,  by  uniting 
with  the  oxygen  of  the  air,  the  products  of  combustion  are  exactly 
the  same  as  though  the  carbon  and  sulfur  were  burned  separately 
with  oxygen,  carbon  dioxid  and  sulfur  dioxid  being  formed. 

Sodium  (Na,  natrium  in  Latin)  is  a  soft  metallic  element  which 
takes  fire  when  thrown  into  water,  and  the  element  chlorin  (Cl) 
is  a  greenish  colored  poisonous  gas,  but  when  united  these  two 
elements  form  the  compound  called  sodium  chlorid  (NaCl),  salt. 


FOUNDATION   FACTS   AND   PRINCIPLES  3 

Chemical  action.  Chemical  reaction  is  the  union  of  two  or  more 
elements  into  a  compound,  or  the  separation  of  a  compound  into 
its  elements,  or  the  formation  of  new  compounds  from  other  com- 
pounds. In  the  most  common  chemical  reactions  heat  is  evolved. 

Place  some  coal  in  the  stove,  raise  the  temperature  to  the  kin- 
dling point,  and  32  pounds  of  the  element  oxygen  entering  the  vent 
of  the  stove  in  gas  form  will  unite  with  12  pounds  of  the  element  car- 
bon in  the  coal  and  44  pounds  of  the  compound  carbon  dioxid  (CO2) 
will  form  and  pass  off  as  a  gas  througn  the  chimney.  After  this 
chemical  reaction  is  completed,  the  stove  is  found  to  contain  only 
a  few  ounces  of  ashes,  which  represent  the  impurities  in  the  coal. 

From  this  compound,  carbon  dioxid  (CO2) ,  which  is  always  pres- 
ent in  the  air  in  small  amount,  all  agricultural  plants  obtain  their 
supply  of  carbon  and  oxygen,  which  together  constitute  about 
90  per  cent  of  the  total  dry  matter  contained  in  plants. 

Combining  weights.  Combining  weights  of  elements  are  the 
relative  proportions  in  which  those  elements  combine  to  form 
compounds.  The  combining  weight  of  the  element  hydrogen  is 
smaller  than  that  of  any  other  element,  and  for  this  reason  all  other 
combining  weights  are  referred  to  that  of  hydrogen  as  the  stand- 
ard, or  unit,  of  weight.  The  combining  weight  of  hydrogen  is  i. 
One  part  of  hydrogen  will  unite  with  35.5  parts  of  chlorin  to  form 
the  compound  hydrogen  chlorid  (HC1),  which  is  also  properly 
called  hydrochloric  acid,  and  sometimes  incorrectly  called  "  mu- 
riatic "  acid.  Thus,  the  combining  weight  of  chlorin  is  35.5. 

We  may  take  i  pound  of  hydrogen  and  let  it  unite  with  35.5 
pounds  of  chlorin  to  form  36.5  pounds  of  the  compound  HC1; 
or  we  may  use  i  ounce  of  hydrogen  and  35.5  ounces  of  chlorin, 
or  i  gram  of  hydrogen  and  35.5  grams  of  chlorin,  or  i  milligram  of 
hydrogen  and  35.5  milligrams  of  chlorin.  All  that  is  necessary  is, 
that  we  maintain  these  proportions.  This  is  one  of  the  absolute 
mathematical  laws  of  chemistry  and  is  fundamental  to  the  prin- 
ciples of  soil  fertility  and  plant  growth.  If  we  try  to  combine  3 
parts  of  hydrogen  with  35.5  parts  of  chlorin,  36.5  parts  of  the  com- 
pound HC1  would  be  formed  and  2  parts  of  hydrogen  would  be 
left  in  its  original  form. 

Atoms.  An  atom  is  the  smallest  particle  of  an  element.  It  is 
not  known  how  small  the  atom  is,  but  it  is  known  that  the  weight  of 


4  SCIENCE  AND   SOIL 

an  atom  of  carbon  is  12  times,  of  oxygen  is  16  times,  of  sulfur  is  32 
times,  and  of  chlorin  is  35.5  times,  as  great  as  the  weight  of  an  atom 
of  hydrogen.  Thus  the  atomic  weights  of  all  other  elements  are 
referred  to  the  weight  of  the  hydrogen  atom  as  the  chemical  unit. 

Molecules.  A  molecule  is  the  smallest  enduring  particle  of  an 
element  or  compound.  The  atom,  if  set  free,  instantly  unites  with 
another  atom  (either  of  the  same  element  or  of  a  different  element) 
to  form  a  molecule,  and  the  molecule  may  endure  permanently. 
One  atom  of  hydrogen  and  one  atom  of  chlorin  unite  to  form  one 
molecule  of  hydrochloric  acid,  HC1.  The  molecular  weight  of  this 
compound  1536.5,  which  is  the  sum  of  the  atomic  weights,  the  weight 
of  the  hydrogen  atom  always  being  i.  It  is  true  that  this  is  an 
arbitrary  standard,  but  so  is  every  common  standard  of  weight 
or  measure,  such  as  the  ounce  or  the  inch  or  the  dollar.  The  inch 
is  an  arbitrary  standard  of  length  to  which  we  may  refer  other 
lengths  or  distances,  and  likewise  the  weight  of  the  hydrogen  atom 
is  an  arbitrary  standard  to  which  we  may  with  equal  accuracy 
refer  the  weights  of  the  atoms  of  all  other  elements,  and  also  the 
weights  of  all  molecules  of  either  compounds  or  elements. 

Atomic  bonds.  Atomic  bonds  are  the  links  of  union  between 
atoms.  This  bond  between  atoms  may  be  likened  to  the  hand  clasp 
between  persons,  except  that  under  normal  conditions  the  hand  of 
one  atom  always  grasps  the  hand  of  another  atom.  If  the  bond  is 
broken,  the  freed  hands  immediately  grasp  other  hands,  breaking 
the  bonds  between  other  atoms  if  necessary  to  secure  union.  At 
the  instant  a  bond  is  broken,  when  free  hands  exist,  the  atoms  are 
called  nascent,  and  in  that  condition  they  have  unusual  power  to 
attack  the  molecules  of  other  elements  or  compounds.  Free 
hydrogen  means  hydrogen  not  combined  with  some  other  element. 
Thus  we  have  nascent  hydrogen  (H),  ordinary  free  hydrogen 
(H^),  and  combined  hydrogen,  as  in  water  (HjO).  Of  course, 
nascent  hydrogen  is  also  free  hydrogen,  but  in  an  extraordinary 
form;  namely,  as  a  free  atom,  which  as  such  can  exist  but  an 
instant  until  it  unites  with  another  atom  of  hydrogen  (or  of  -some 
other  element)  to  form  a  molecule. 

Valence.  Valence  refers  to  the  number  of  bonds,  or  hands,  pos- 
sessed by  an  atom.  The  hydrogen  atom  has  but  one  hand  (H — ), 
while  the  oxygen  atom  has  two  hands  ( — O — ),  and  the  carbon 


FOUNDATION   FACTS   AND   PRINCIPLES  5 

atom  has  four  hands  (=C=).  In  hydrogen  molecules  the  atoms 
are  always  in  pairs  (H — H  or  Hj).  Thus  the  weight  of  the  hydro- 
gen molecule  is  two,  because  it  contains  two  of  the  unit  atoms.  The 
atom  of  oxygen  weighs  sixteen  times  as  much  as  the  hydrogen 
atom,  consequently  16  is  the  atomic  weight,  or  the  combining 
weight,  of  the  element  oxygen.  The  molecule  of  ordinary  oxygen 
contains  two  atoms  (O  =O  or  Og) ,  but  there  is  a  form  of  oxygen, 


called  ozone,  which  contains  three  atoms  in  the  molecule  (O O 

or  Og).  The  molecular  weight  of  ordinary  oxygen  is  32,  while  the 
molecule  of  ozone  weighs  48  times  as  much  as  one  hydrogen 
atom.  One  oxygen  atom  has  power  to  hold  two  hydrogen  atoms 
(H — O — H  or  H2O).  This  is  a  compound  which  might  be 
called  dihydrogen  oxid,  but  which  is  commonly  called  water.  The 
molecular  weight  of  water  is  18,  the  sum  of  the  atomic  weights. 
Separately,  hydrogen  and  oxygen  are  both  gases  under  ordinary 
conditions,  but  the  compound  H2O  possesses  different  properties, 
being  a  liquid  at  ordinary  temperatures,  although  water  becomes 
a  gas  at  high  temperature  and  a  solid  at  low  temperature. 

While  it  is  common  knowledge  that  this  compound  exists  in 
three  forms,  solid,  liquid,  and  vapor,  and  that  it  is  easily  changed 
from  solid  ice  to  liquid  water  and  from  liquid  to  vapor  (steam), 
it  is  not  so  generally  known  that  most  elements  and  most  com- 
pounds may  exist  in  each  of  these  three  forms  under  proper  condi- 
tions of  temperature  and  pressure. 
One  atom  of  carbon  may  combine  with  four  atoms  of  hydrogen, 

/Hv        /H  x 

forming  the  gas  compound  I       XY       or  CH4 )  called  methane  or 

VH/     \H 

marsh  gas,  a  constituent  of  illuminating  gas,  and  sometimes  formed 
in  stagnant  marshes.  This  hydrocarbon  has  a  molecular  weight 
of  1 6  and  is  the  lowest  in  a  very  large  series  of  compounds  contain- 
ing only  hydrogen  and  carbon.  One  atom  of  carbon  with  its  four 
bonds  may  unite  with  two  atoms  of  oxygen,  forming  carbon  dioxid 
(O  =  C  =  O  or  CO2) ,  a  chemical  reaction  which  occurs  in  the  com- 
bustion of  coal  or  other  substances  containing  carbon,  as  already 
explained. 

Monovalent  atoms  have  one  bond,  or  one  hand  (mono  means 


6  SCIENCE  AND   SOIL 

one,  as  in  monotone)  ;  bivalent  atoms  have  two  bonds  (bi  or  di 
means  two);  trivalent  atoms  have  three  bonds;  tetravalent,  four 
bonds;  pentavalent,  five  bonds;  hexavalent,  six  bonds;  hepta- 
valent  atoms  have  seven  bonds;  and  octovalent  atoms  have  eight 
bonds,  with  power  to  hold  four  of  the  bivalent  atoms  of  oxygen. 

There  are  a  few  cases  in  which  the  atom  does  not  make  common 
use  of  all  the  bonds  it  possesses.  Thus  the  nitrogen  atom  has  five 
bonds,  or  hands,  but  in  some  compounds  only  three  bonds  are  used 
to  hold  other  atoms.  It  might  be  conceived  in  this  case  that  the 
other  two  hands  are  clasped  together,  and  this  conception  might 
even  be  extended  to  cover  a  molecule  composed  of  a  single  biva- 
lent atom  (such  as  mercury  and,  possibly,  argon).  One  atom  of 
nitrogen  and  three  atoms  of  hydrogen  form  the  compound  called 
ammonia  (NHg).  This  compound  is  frequently  sold  in  fertilizers, 
but  the  hydrogen  has  no  money  value  because  water  (I^O)  con- 
tains hydrogen.  The  molecular  weight  of  ammonia  is  17,  of  which 
the  nitrogen  atom  is  14  and  the  hydrogen  atoms  are  3.  If  a  fer- 
tilizer is  guaranteed  to  contain  17  per  cent  of  ammonia,  it  should 
contain  14  per  cent  of  the  element  nitrogen;  while  8|  per  cent  of 
ammonia  is  equivalent  to  only  7  per  cent  of  nitrogen.  Ammonia 
itself  contains  ^,  or  82  per  cent,  of  the  element  nitrogen. 

In  the  compound  called  ammonium  chlorid  (NH4C1),  the  atom 
of  nitrogen  is  pentavalent;  that  is,  it  has  and  uses  five  bonds: 
K  H 

N-C1.     The   molecular  weight   of  this  compound   is   53.5 


(14  +  4  +  35-5),  and  it  contains  -^-,  or  26  per  cent,  of  nitrogen. 

53-5 
Phosphorus  is  another  element  which  sometimes  uses  only  three 

/H 

bonds,  as  in  hydrogen  phosphid,  P^-H,  and  in  phosphorus  trichlorid, 

XH 

/Cl 
P^-C1,  and  sometimes  five  bonds,  as  in  phosphorus  pentachlorid, 

XC1 
CL        JC\ 

^P^-C1.     Thus,  the  hydrogen  phosphid  contains  f^,  or  91  per 
CK     XC1 


FOUNDATION   FACTS   AND   PRINCIPLES  7 

cent,  of  phosphorus  (the  atomic  weight  of  phosphorus  being  31), 
while  the  phosphorus  pentachlorid  contains  less  than  15  per  cent 
of  phosphorus. 

Nitrogen  and  phosphorus  are  in  some  respects  very  much  alike, 
and  in  other  respects  they  are  very  unlike.  They  are  the  two  most 
precious  elements  of  plant  food,  and  they  deserve  from  the  author 
and  from  the  reader  all  of  the  consideration  they  are  to  receive  in 
this  book. 

The  gas  law.  This  law  is  that  equal  volumes  of  gases  under  like 
conditions  of  temperature  and  pressure  contain  the  same  number 
of  molecules.  In  other  words,  in  the  gas  form,  every  molecule 
occupies,  or  controls,  the  same  amount  of  space.  Thus,  the  hydro- 
gen molecule,  with  a  weight  of  2,  occupies  as  much  space  as  the 
oxygen  molecule,  which  weighs  32,  or  the  molecule  of  carbon  dioxid, 
weighing  44,  or  of  sulfur  dioxid  with  a  molecular  weight  of  64. 
(The  atomic  weight  of  sulfur  is  32.) 

If  a  6-gallon  bottle  holds  2  grams  of  hydrogen  (H2),  it  will 
hold  32  grams  of  oxygen  (O2),  28  grams  of  nitrogen  (N2),  16  grams 
of  methane  (CH4),  17  grams  of  ammonia  gas  (NHg),  44  grams  of 
carbon  dioxid  (CO^ ,  64  grams  of  sulfur  dioxid  (SOg)  ,and  a  gram- 
molecule  (the  molecular  weight  in  grams)  of  any  other  gas.  This 
law  does  not  apply  to  liquids  or  solids,  but  only  to  gases. 

Chemical  symbols.  A  symbol  is  used  to  represent  one  atom  of 
an  element.  H  stands  not  only  for  the  element  hydrogen,  but  also 
for  one  atom  of  hydrogen  with  a  combining  weight  of  i.  Likewise 
S  stands  for  sulfur  and  for  one  atom  of  sulfur,  and  represents  a 
weight  of  .32. 

Chemical  formulas.  A  formula  is  used  to  represent  a  molecule 
and  shows  the  kind  and  the  number  of  atoms  contained  in  the 
molecule.  The  formula  H2O  represents  one  molecule  of  water, 
containing  two  atoms  of  hydrogen,  each  having  a  combining 
weight  of  i,  and  one  atom  of  oxygen,  with  a  weight  of  16.  Thus, 
the  molecular  weight  of  water  is  18.  The  formula  Cag(PO4)2 
(read:  Ca  three,  PO  four,  twice)  represents  one  molecule  of 
tricalcium  phosphate,  the  valuable  phosphorus  compound  contained 
in  bones  and  in  natural  phosphate  rock.  The  metallic  element 
calcium  (Ca)  is  also  contained  in  limestone,  which  is  calcium  car- 
bonate (CaCOs) ,  and  in  quicklime,  or  burned  lime,  which  is  calcium 


8  SCIENCE   AND    SOIL 

oxid  (CaO).  The  atomic  weight  of  calcium  is  40.  The  subscript 
figures  used  in  a  chemical  formula  always  refer  to  the  preceding 
element,  or  to  the  inclosed  group  of  elements  if  parentheses 
are  used.  In  the  calcium  phosphate,  Ca3(PO4)2,  the  subscript  3 
shows  that  three  atoms  of  calcium  are  contained  in  the  molecule. 
The  parentheses  are  used  to  inclose  a  group  of  atoms  (one  atom 
of  phosphorus  and  four  atoms  of  oxygen)  which  occurs  in  many 
other  compounds,  as  in  H3PO4  (phosphoric  acid),  FePO4  (iron 
phosphate),  etc.  (Fe  is  fromferrum,  the  Latin  word  for  iron,  and 
I  is  the  symbol  used  for  the  element  iodin.)  The  subscript  2  follow- 
ing the  parenthesis  in  Ca3(PO4)2  means  that  the  molecule  contains 
the  PO4  group  twice,  and  for  this  reason  Ca3(PO4)2  is  a  better  for- 
mula than  Ca3P2O8,  which  may  also  be  correctly  used.  A  mole- 
cule of  tricalcium  phosphate  contains  three  atoms  of  calcium 
(3  X  40  =  120),  two  atoms  of  phosphorus  (2  x  31  =  62),  and  eight 
atoms  of  oxygen  (2  X  4  X  16  =  128),  and  the  molecular  weight  is 
310  (120  +  62  +  128),  of  which  the  phosphorus  represents  only  62. 
Thus,  tricalcium  phosphate  contains  -/^$,  or  20  per  cent,  of  the 
element  phosphorus.  In  other  words,  one  fifth  of  pure  tricalcium 
phosphate  is  phosphorus,  while  the  remaining  four  fifths  consist 
of  calcium  and  oxygen  in  nearly  equal  parts. 

The  law  of  constant  proportions.  This  law  is  that  in  every  chemi- 
cal combination  the  constituents  occur  in  definite  and  constant 
proportions  by  weight.  The  percentage  of  phosphorus  in  pure 
tricalcium  phosphate  is  absolutely  constant.  It  matters  not 
whether  the  compound  is  made  in  the  United  States,  in  Germany, 
or  in  Japan,  nor  whether  it  is  obtained  from  bones  or  from  phos- 
phate rock,  the  percentage  of  phosphorus  it  contains  is  always 
the  same,  if  the  compound  is  pure.  This  percentage  is  exactly  20, 
according  to  the  most  accurate  accepted  determinations.  The 
atomic  weights  are  determined  by  several  different  methods,  but, 
even  with  the  finest  and  most  accurate  balances  and  other  instru- 
ments and  means,  absolute  exactness  may  not  be  achieved,  be- 
cause of  the  human  error.  No  man  can  measure  a  mile  with 
absolute  exactness,  because  two  different  measurements  made  by 
one  man  may  vary  by  an  inch,  a  tenth  of  an  inch,  or,  at  least,  by 
a  hundredth  or  a  thousandth  of  an  inch. 

According  to  the  chemical  law,  the  proportion  of  the  different 


FOUNDATION   FACTS   AND    PRINCIPLES  9 

elements  in  any  pure  compound  is  absolutely  definite  and  constant, 
in  strict  accordance  with  the  chemical  law,  and  the  proportion 
can  be  determined  with  ten  times  the  degree  of  accuracy  required 
for  all  practical  purposes ;  nevertheless,  the  determination  may  not 
be  absolutely  exact. 

While  all  atomic  weights  are  essentially  referred  to  hydrogen  as 
unity,  the  mathematical  basis  is  exactly  16  for  the  atomic  weight 
of  oxygen,  because  the  element  oxygen  constitutes  in  quantity 
one  half  of  the  earth's  crust  (including  the  air,  the  ocean,  and  the 
solid  crust  to  a  depth  of  ten  miles),  and  forms  compounds  with 
nearly  all  other  elements,  thus  affording  closer  comparisons  than 
hydrogen. 

The  known  chemical  elements.  In  the  accompanying  table  is 
the  complete  list  of  80  known  elements.  For  convenience  the  more 
common  elements,  that  every  one  should  know,  are  given  in  one 
group,  arid  the  rare  elements,  that  few  people  have  ever  seen, 
are  grouped  by  themselves. 

The  symbols  used  for  the  chemical  elements  are  essentially  the 
same  in  all  languages.  In  a  few  cases  where  the  modern  name  varies 
in  different  languages,  the  nations  have  agreed  upon  a  symbol 
derived  from  the  Latin  name  of  the  element;  as,  for  example,  Fe 
for  iron  (ferrum  in  Latin),  K  for  potassium  (kalium),  and  Na  for 
sodium  (natrium). 

Some  of  the  atomic  weights  of  the  rare  elements  have  not  yet 
been  determined  with  a  sufficient  degree  of  accuracy  to  justify 
assigning  a  more  specific  value  than  the  nearest  whole  number. 
Further  investigation  must  determine  whether  such  whole  numbers 
are  correct.  It  is  a  noteworthy  fact  that  the  chemists  of  the  world 
are  agreed  that,  of  these  forty  more  common  elements,  sixteen 
have  atomic  weights  that  differ  from  whole  numbers  by  less  than 
.05,  and'  twelve  others  differ  only  by  about  .1,  thus  showing 
twenty-eight  of  the  best-established  atomic  weights  apparently 
grouped  with  relation  to  the  unit,  with  only  twelve  scattering ; 
and  some  of  these  (as  nickel)  are  doubtful,  while  others  are  high 
atomic  weights  with  consequent  possibilities  of  error,  the  accepted 
atomic  weights  of  gold  and  platinum  both  having  been  changed  by 
.5  within  recent  years.  These  data  and  the  recognized  periodic 
law,  that  the  properties  of  the  elements  are  periodic  functions  of  their 


10 


SCIENCE   AND   SOIL 


TABLE    i.   ELEMENTS,    SYMBOLS,    AND   INTERNATIONAL   ATOMIC   WEIGHTS 
FOR  1909.     (Decimals,  including  ciphers,  indicate  supposed  accuracy.) 


THE  MORE  COMMON  ELEMENTS 

THE  RARER  ELEMENTS 

Name 

Symbol 

Atomic 
Weight 

Name 

Symbol 

Atomic 
Weight 

Aluminum    .... 
Antimony  (Stibium)  . 
Argon      

Al 
Sb 
A 
As 
Ba 

Bi 
B 
Br 
Cd 
Ca 

C 

Cl 
Cr 
Co 

Cu 

F 
Au 
H 
I 
Fe 

Pb 
Li 
Mg 
Mn 

Hg 
Mo 

Ni 
N 
O 
P 

Pt 
K 

Si 
Ag 

Na 

Sr 
S 
Sn 
Ti 
Zn 

27.1 
1  20.  2 

39-9 
75-o 
137-4 
208.0 

II.  0 

79-9 
112.4 
40.1 

I2.O 

35-5 
52-1 

59-o 
63.6 

19.0 
197.2 
1.008 
126.9 
55-9 
207.1 
7.0 
24-3 
54-9 

2OO.O 
96.0 

58.7 
14.0 
IO.OOO 
3I.O 

195.0 

39-i 
28.3 
107.9 
23.0 

87.6 
32.1 
119.0 
48.1 
65-7 

Caesium       .... 
Cerium   
Columbium      .     .     . 
Dysprosium      .     .     . 
Erbiym        .... 

Cs 
Ce 
Cb 
Dy 
Er 

Eu 
Gd 
Ga 
Ge 
Gl 

He 
In 
Ir 
Kr 
La 

Nd 
Ne 
Os 
Pd 
Pr 

Ra 
Rh 
Rb 
Ru 

Sa 

Sc 
Se 
Ta 
Te 
Tb 

Tl 
Th 
Tm 
W 
U 

V 
Xe 
Yb 
Y 
Zr 

132.8 
140.3 

93-5 
162.5 
167.4 

152 

157-3 
69.9 

72-5 
9.1 

4.0 
114.8 

J93-1 
81.8 
139.0 

144-3 
20 
190.9 
106.7 
140.6 

226.4 
102.9 

85-5 
101.7 

150.4 
44.1 
79-2 
181 

127-5 
159-2 
204.0 
232.4 
168.5 
184.0 
238-5 

5i-2 
128 
172.0 
89.0 
90.6 

Arsenic 

Barium         .... 

Bismuth  

Europium    .... 
Gadolinium      .     .     . 
Gallium       .... 
Germanium 
Glucinum    .... 

Helium 

Boron      

Bromin    ..... 

Cadmium     .... 
Calcium  

Carbon 

Chlorin    

Indium   

Chromium   .... 
Cobalt     

Iridium        .... 
Krypton       .... 
Lanthanum      .     .     . 

Neodymium     .     .     . 
Neon       

Copper  (Cuprum) 
Fluorin    

Gold  (Aurum)  .     .     . 
Hydrogen     .... 
lodin        

Osmium       .... 
Palladium    .... 
Praseodymium      .     . 

Radium       .... 
Rhodium     .... 
Rubidium    .... 
Ruthenium       .     .     . 

Samarium    .... 

Scandium    .... 
Selenium      .... 
Tantalum    .... 
Tellurium    .... 
Terbium      .... 

Thallium     .... 
Thorium      .... 
Thulium           ... 
Tungsten  (Wolfram) 
Uranium      .... 

Vanadium   .... 
Xenon     

Iron  (Ferrum)  .     .     . 

Lead  (Plumbum)  .     . 
Lithium        .... 
Magnesium       .     .     . 
Manganese        .     .     . 
Mercury        (Hydrar- 
gyrum)     .... 

Molybdenum    .     .     . 
Nickel      

Nitrogen       .... 
Oxvgren    . 

Phosphorus       .     .     . 

Platinum      .... 
Potassium  (Kalium)  . 
Silicon     

Silver  (Argentum) 
Sodium  (Natrium)     . 

Strontium     .... 
Sulfur 

Tin  (Stannum)      .     . 
Titanium      .... 
Zinc    

Ytterbium    .... 
Yttrium       .... 
Zirconium    .... 

FOUNDATION   FACTS   AND   PRINCIPLES  n 

atomic  weights,1  together  with  the  recently  discovered  radium  and 
radio  activity,  and  the  evidences  2  of  accomplished  transformation 
of  one  element  into  another,  strongly  indicate  a  common  origin 
for  different  elements,  and  lend  to  the  subject  a  present-day  in- 
terest as  intense  as  ever  moved  the  alchemist  to  try  to  turn  the 
baser  metals  into  gold. 

1  It  is  worth  while  to  note  some  relations  that  exist  between  the  monovalent 
elements  fluorin,  chlorin,  bromin,  iodin;  between  the  bivalent  elements  oxygen, 
sulfur,  selenium,  molybdenum;  between  the  trivalent  (or  pentavalent)  nitrogen, 
phosphorus,  arsenic,  antimony;  and  also  between  the  tetravalent  carbon,  silicon, 
titanium,  and  germanium: 

Fluorin  Chlorin  Bromin  Iodin 

F  =  i9  01  =  35.5  Br  =  8o  1  =  127 

HF  HC1  HBr  HI 

Oxygen  Sulfur  Selenium  Molybdenum 

O  =  16  5  =  32.1  Se  =  79.2  Mo  =  96 

H2O  H2S  H2Se 


H2SO4  H2SeO4  H2MoO4 


Nitrogen  Phosphorus  Arsenic  Antimony 

N  =  14  P  =  31  As  =  75  Sb  =  120.2 

NHs  PH3  AsH3  SbH3 

N2O6  P2O6  As2O6  Sb2O6 

Carbon  Silicon  Titanium  Germanium 

C  =  i2  Si  =  28.4  Ti  =  48  Ge  =  72.5 
SiH4 


CO2  SiO2  TiO2  GeO2 

Aside  from  the  similarity  of  valence  and  other  properties  and  of  compounds 
formed,  there  is  interest  in  the  relation  of  atomic  weights,  especially  in  the  second 
and  fourth  groups,  and,  even  in  the  fact  that  the  atomic  weight  of  antimony  is  so 
nearly  the  sum  of  the  other  three  in  the  group. 

2  In  1907  Ramsay  and  Cameron,  of  England,  reported  that  they  had  reduced 
copper,  in  the  presence  of  radium  emanation,  into  other  elements  of  the  same  series: 
potassium,  sodium,  lithium.  (See  Nature,  July,  1907,  and  Journal  of  the  Chemical 
Society,  September,  1907.)  The  correctness  of  Ramsay  and  Cameron's  experiments 
has  been  called  in  question  by  Mme.  Curie  and  Mile.  Gleditsch;  Comptes  rendus, 
147,  345  (1908);  Science,  December  4,  1908. 


CHAPTER  II 

THE   MORE    COMMON   ELEMENTS   AND    COMPOUNDS 

Important  elements.  Fifteen  elements  are  of  special  interest  and 
importance  in  the  study  of  soil  fertility,  because  they  are  commonly 
found  in  plants  and  animals  and  because  they  so  largely  constitute 
the  soil  and  air  and  ocean  and  the  common  things  of  earth.  Of 
these  fifteen  elements,  ten  are  known  to  be  essential  to  plant 
growth;  eight  of  them  constitute  98  per  cent  of  the  solid  crust  of 
the  earth;  four  of  them  constitute  99. 6  per  cent  of  the  ocean,  about 
96.4  per  cent  being  water  (H2O)  and  3.2  per  cent  common  salt 
(NaCl);  and  two  of  them  (nitrogen  and  oxygen)  constitute  98.5 
per  cent  by  weight  of  the  dry  atmosphere,  about  1.5  per  cent  of 
the  air  consisting  of  the  recently  discovered  element,  argon. 

The  ten  essential  elements  of  plant  food  may  be  grouped  as 
follows : 

C,  H,  O,  obtained  by  plants  from  air  and  water. 

P,  K,  N,  sometimes  deficient  in  soils,  and  of  money  value  as 
plant  food. 

S,  Ca,  Fe,  Mg,  required  in  small  amounts  and  not  likely  to  be 
deficient  in  soils. 

The  five  other  elements  commonly  present  in  plants  are  silicon, 
aluminum,  sodium,  chlorin,  and  manganese. 

The  reader  is  earnestly  advised  to  learn  by  groups  *  the  name 
and  atomic  weight  and  the  valence  of  each  of  these  important 
elements,  and  the  following  table  is  constructed  for  this  purpose. 

Aside  from  the  name,  symbol,  atomic  weight,  and  valence, 
Table  2  furnishes  some  extremely  valuable  and  useful  information 
concerning  the  occurrence  and  relative  abundance  of  the  elements 
which  essentially  constitute  the  crust  of  the  earth,  the  ocean,  the 
air,  and  the  agricultural  plants  and  animals.  These  data  are  based 

1  The  author  consents  to  the  students'  memory  key:  "C.  HOPK'NS'  CaFe,-Mg, " 
if  Mg  stands  for  "Mighty  good  "  and  the  omission  of  I,  for  modesty. 


THE  MORE  COMMON  ELEMENTS  AND  COMPOUNDS     13 

upon  the  recent  computations  of.  Professor  F.  W.  Clarke  of  the 
United  States  Geological  Survey  for  the  average  composition  of 
the  ocean  and  of  the  earth's  crust 1  to  a  depth  of  ten  miles,  essen- 
tially upon  Sir  William  Ramsay's  recent  estimate  for  the  average 
composition  of  air,  and  upon  the  author's  compilations  and  com- 
putations for  the  average  composition  of  shelled  corn  (maize). 


TABLE  2.   THE  MORE  IMPORTANT  ELEMENTS 


NAME 

SYMBOL 

ATOMIC 
WEIGHT 
(0=i6) 

VALENCE,  OR 
NUMBER  OF 
BONDS 

OCCURRENCE 

In  Earth's 
Crust 
(Per  Cent) 

In  the 
Ocean 
(Per  Cent) 

In  the 
Air 
(Per  Cent) 

In  the 
Corn  Ker- 
nel 
(Per  Cent) 

Oxygen   .     . 
Carbon    .     . 
Hydrogen 

o 
c 

H 

16 

12 
I 

2 

4 

I 

47.07 
.20 
.22 

85-79 

23.00 
.OI 

46.000 
45.000 
6.400 

10.67 

Nitrogen 
Phosphorus 
Potassium    . 

N 
P 
K 

14 

31 
39 

3  or  5 

3  «r  5 

i 

trace 
.11 
2.46 

75-5° 

1.760 
.300 

•340 

.04 

Magnesium 
Calcium  .     . 
Iron    .     .     . 
Sulfur      .     . 

Mg 
Ca 

Fe 

S 

24-3 
40 

56 
32 

2 
2 

2,  3»  6,  or  7 
2,  4,  or  6 

2.40 
3-44 

4-43 
.11 

.14 

•°5 

.125 
.022 
.008 
.OO4 

.09 

Silicon     .     . 
Aluminum   . 
Sodium   .     . 
Chlorin    . 
Manganese 

Si 
Al 
Na 
Cl 
Mn 

28.3 
27 
23 
35-5 
55 

4 

3 

i 

i,  3,  5,  or  7 
2,-3,  6,  or  7 

28.06 
7.90 

2-43 
.07 
.07 

.014 

I.I4 
2.07 

.013 
.013 

Titanium 
Argon 

Ti 
A 

48 
40 

4 

(?) 

.40 

1.48 

Totals 

99.36  2 

99-99 

99-99  3 

99-99 

1  United  States  Geological  Survey  Bulletin   330  (1908).     The  data  for  phos- 
phorus and  potassium  include  analyses  of   1671  and  2110  different  samples,  re- 
spectively, of  representative  rocks,  some  of  which  were  kindly  furnished  to  the  author 
by  Doctor  Clarke  since  Bulletin  330  was  published. 

2  About  sixty  other  elements  (most  of  them  very  rare)  must  account  for  this 
deficiency. 

3  Constant  traces  of  helium,  neon,  krypton,  and  xenon  are  also  found  in  the  air, 
of  which  they  may  constitute  five  parts  per  million.    Varying  amounts  of  moisture, 
compounds  of  nitrogen,  sulfur,  chlorin,  and  more  or  less  dust,  also  exist  in  the  air. 


14  SCIENCE  AND   SOIL 

It  may  well  be  stated  here  Jthat  plants  secure  their  supply  of 
both  carbon  and  oxygen  from  the  carbon  dioxid  of  the  air.  The  .01 
per  cent  of  carbon  (C  =  12)  shown  in  the  table  is  equivalent  to 
nearly  .04  per  cent  of  carbon  dioxid  (CO2  =  44).  The  hydrogen  of 
plants  is  taken  from  the  water  absorbed  by  the  roots.  The  corn 
plant  secures  its  supply  of  nitrogen  from  the  "  trace  "  contained 
in  the  earth's  crust,  which,  however,  amounts  to  about  .25  per  cent, 
in  the  tilled  stratum  of  a  good  soil.  Under  proper  conditions 
legume  plants  secure  more  or  less  of  their  nitrogen  from  the  air. 
The  remaining  six  essential  elements  are  secured  only  from  the  soil 
by  all  plants. 

Of  the  atmosphere,  ocean,  and  solid  crust  (ten  miles  deep), 
the  solid  crust  constitutes  about  93  per  cent  of  the  whole ;  while 
the  entire  atmosphere  amounts  to  only  .03  per  cent.  These  addi- 
tional facts  make  possible  a  mathematical  comparison  between  the 
supply  and  crop  requirements  of  carbon  and  oxygen  (in  CO2) 
and  nitrogen  in  the  air,  and  emphasize  the  importance  of  the 
carbon  cycle  and  of  the  circulation  of  some  other  elements,  all  of 
which  is  more  fully  discussed  and  explained  in  the  following  pages. 

A  ready  working  knowledge,  sufficient  for  everyday  use,  lies  at 
the  basis  of  success  in  every  industry  and  profession.  It  is  worth 
while  to  have  in  mind  a  few  fundamental  facts  relating  to  the  seven- 
teen elements  named  in  Table  2,  which  constitute  more  than  99 
per  cent  of  earth,  sea,  and  air,  and  of  all  plants  and  animals. 
Nothing  can  be  made  of  nothing. 

Compounds  consist  of  two  or  more  elements,  and  the  molecule 
of  a  compound  must  contain  two  or  more  atoms.  If  one  knows  the 
valence  of  the  elements,  he  is  then  in  control  of  much  information 
of  very  great  value  in  relation  to  compounds.  Valence  is  the  key 
to  the  understanding  of  compounds  and  chemical  reactions.  Table 
2  gives  this  information  for  the  very  important  elements. 

Three  of  these  elements  —  hydrogen,  potassium,  and  sodium  — 
have  only  one  bond,  or  hand,  for  each  atom  (H — ,  Na — ,  and 
K — );  while  chlorin  (Cl)  may  use  i,  3,  5,  or  7  bonds. 

Three  other  elements  have  only  two  bonds  for  each  atom 
(O  =  ,  Mg  =  ,  and  Ca=),  these  elements  being  strictly  bivalent. 
Sulfur  sometimes  uses  only  two  bonds  (in  H2S  and  CS2),  but  may 
use  four  or  six. 


THE  MORE  COMMON  ELEMENTS  AND  COMPOUNDS     15 

Iron  and  manganese  are  alike  peculiar,  with  a  valence  of  2,  3,  6, 
or  7. 

Aluminum  is  a  trivalent  element  with  three-handed  atoms, 
while  nitrogen  and  phosphorus  may  use  either  three  or  five 
bonds. 

This  leaves  only  the  strictly  tetravalent  family,  carbon  (=  C  =  ), 
silicon  (  =  Si=),  and  titanium  (=Ti  =  ).1 

When  an  iron  atom  uses  three  hands,  it  is  called  -ic  iron,  but  if  it 
uses  only  two  hands  it  is  called  -ous  iron.  Thus  we  have  the  ferrous 
chlorid  (FeCl2)  and  ferric  chlorid  (FeCl3) ;  also  ferrous  oxid  (FeO) 
and  ferric  oxid  (Fe2Og).  Likewise,  when  phosphorus  uses  only 
three  bonds,  it  is  called  -ous  phosphorus,  but  with  the  five  bonds 
in  use  it  is  -ic  phosphorus,  as  in  phosphorous  chlorid  (PClg)  and 
phosphoric  chlorid  (PC16),  which  are  also  called  phosphorus  tri- 
chlorid  and  phosphorus  pentachlorid,  the  endings,  -ous  and  -ic, 
being  unnecessary  when  the  valence  is  specified  in  the  number  of 
chlorin  atoms  held. 

Matter  may  exist  in  three  distinctly  different  forms  or  classes 
which  might  be  called  "  monary  "  (single),  "fo'nary"  (double),  and 
"  /raiary,"  or  ternary  (triple). 

First,  matter  may  exist  in  the  form  of  free  or  uncombined  ele- 
ments; as  solid  metallic  iron,  aluminum,  magnesium,  calcium, 
sodium,  or  potassium;  as  solid  nonmetallic  carbon,  phosphorus, 
sulfur,  or  silicon;  as  liquid  mercury  or  bromin;  or  as  gaseous 
oxygen,  nitrogen,  hydrogen,  or  chlorin.  This  might  be  termed 
the  "  wonary  "  form,  all  atoms  in  the  molecule  being  of  the  one 
element. 

Second,  matter  may  exist  in  binary  compounds ;   that  is,  with 

1  Argon  is  of  interest  chiefly  because  it  is  so  very  common  and  yet  so  recently 
discovered.  Argon  is  everywhere  present  in  the  air  and  we  respire  more  than  an 
ounce  a  day  of  that  element.  It  is  an  invisible  gas,  and  because  it  is  mixed  with  so 
much  nitrogen  (which  it  resembles  somewhat)  and  oxygen,  and  cannot  be  seen, 
it  would  be  less  easily  discovered  than  many  other  elements;  but  the  chief  difficulty 
in  detecting  it  by  chemical  methods  was  due  to  its  chemical  inaction.  Because  of  this 
inaction,  it  has  been  named  argon,  which  means  without  action.  When  the  ele- 
ment was  discovered  and  very  thoroughly  investigated,  the  discoverers  (Rayleigh 
and  Ramsay,  in  1894)  concluded  that  the  argon  atom  has  no  valence,  — no  hand  with 
which  to  clasp  the  hand  of  another  atom,  either  of  argon  or  of  any  other  element. 
In  other  words,  they  discovered  that  argon  forms  no  compounds,  and  that  the 
molecule  of  argon  is  monatomic  (man  or  mono  means  one,  as  in  monotone  =  one 
tone).  Later  investigations  indicate,  however,  that  argon  has  some  weak  affinities. 


1  6  SCIENCE  AND   SOIL 

two  elements  represented  in  the  molecule.  In  the  name  of  such  a 
compound  both  elements  are  expressed,  and  sometimes  the  name 
also  includes  the  number  of  atoms  of  each  of  the  elements  in  the 
molecule,  as  phosphorus  pentachlorid  (PC15)  .  As  a  rule,  the  name 
of  one  element  is  modified  slightly  so  as  to  end  in  -id,  a  termination 
that  means  that  the  compound  is  binary,  containing  but  two 
elements.  (Any  exception  to  this  rule  will  be  self-explanatory.) 
Thus'  sodium  chlorid  must  contain  only  two  elements,  sodium 
and  chlorin,  because  of  the  names  and  the  ending  -id;  and,  since 
sodium  must  be  monovalent  and  chlorin  may  be,  the  formula 
for  the  molecule  is  probably  Na  —  Cl,  which  is  correct  for  com- 
mon salt. 

As  a  matter  of  fact,  chlorin  is  always  monovalent  in  binary 
compounds  with  metals.  Calcium  oxid  (quicklime)  must  be  a 
binary  compound  of  the  two  strictly  bivalent  elements,  calcium 
and  oxygen,  and  the  molecular  formula  may  be  Ca=O,  which  is 
also  correct.  Calcium  chlorid  should  be  Ca=Cl2;  and  magnesium 
chlorid,  Mg=Cl2;  and  potassium  oxid,  K2=O;  hydrogen  sulfid, 
H2  =  S;  sulfur  dioxid,  SO2  (O  =  S=O);  and  sulfur  trioxid,  SO8 
(in  which  the  sulfur  atom  must  use  six  bonds),  all  of  which  are 
correct.  More  complex  molecules,  which,  however,  are  easily 
understood,  are  aluminum  oxid  (A12O3)  and  phosphorus  pentoxid 
(P2O6)  .  The  aluminum  atom  has  three  bonds  (or  hands)  ,  and  the 
phosphorus  uses  five  bonds  in  this  oxid,  while  the  oxygen  atom  is 
always  bivalent,  having  but  two  hands.  There  are  six  bonds  of 
union  in  aluminum  oxid  and  ten  bonds  in  phosphorus  pentoxid, 


P\° 
thus:  A1;>O,     /O.  Thus,  if  one  knows  the  name,  the  atomic 

Al<o  P|O 

^O 

weight,  and  the  valence  of  the  fifteen  most  important  elements, 
he  has  the  key  to  the  formula  and  percentage  composition  of  their 
binary  compounds. 

Third,  matter  may  exist  in  ternary  (triple)  compounds,  with 
three  elements  represented  in  the  molecule.  Most  ternary  com- 
pounds contain  oxygen,  and,  in  naming  such  compounds,  the  most 
common  rule  is  to  express  the  names  of  only  two  of  the  elements 


THE  MORE  COMMON  ELEMENTS  AND  COMPOUNDS     17 

and  then  to  employ  a  short  ending  to  designate  the  oxygen. 
Thus,  the  ending  -ate  commonly  means  oxygen.  Ternary  com- 
pounds may  best  be  studied  in  groups,  in  which  the  relation  of 
oxygen  to  one  of  the  other  elements  is  constant.  Thus,  the  car- 
bonates constitute  a  large  class  of  compounds  in  which  the  group, 
or  radicle  ( =COg) ,  is  always  present.  The  structural  formula  for 

~°\ 

this  radicle  is  as  follows:          yC  =  O.    From  this  it  will  be  seen 

— cr 

that  the  carbonate  radicle  has  two  free  hands,  or  bonds,  capable 
of  holding  two  monovalent  atoms  or  one  bivalent  atom.  Now, 
the  fact  is,  that  almost  any  metallic  element  can  join  hands  with 
this  radicle.  Thus  we  have  calcium  carbonate  (CaCO3) ,  magnesium 
carbonate  (MgCO3),  ferrous  carbonate  (FeCOg),  sodium  carbonate 
(Na-jCOg),  etc. 

The  nitrate  radicle  is  — NO3,  as  in  sodium  nitrate  (NaNO3) . 
The  chlorate  radicle  is — C1O3,  as  in  potassium  chlorate  (KC1O3). 
The  silicate  radicle  is  =SiO3  (like  the  carbonate  radicle  =CO3). 
The  sulfate  radicle  is  =SO4,  as  in  calcium  sulfate  (CaSO4). 
The  phosphate  radicle  is  =PO4,  as  in  ferric  phosphate  (FePO4). 

If  we  can  remember  these  six  radicles,  we  have  the  key  to  the 
constitution  and  composition  of  a  large  number  of  ternary  com- 
pounds, some  of  which  are  of  the  greatest  importance  in  soil  fer- 
tility; as,  for  example,  limestone,  which  is  calcium  carbonate 
(CaCO3) ;  land  plaster,  which  is  calcium  sulfate  (CaSO^ ;  and  the 
important  compound  in  phosphate  rock  and  in  bones,  called  "  bone 
phosphate,"  which  is  calcium  phosphate,  Ca.&(POJz,  also  properly 
called  tricalcium  phosphate. 

When  the  element  chlorin,  or  the  element  sulfur,  or  any  of  these 
radicles  join  hands  with  metallic  elements,  the  resulting  compound 
is  called  a  salt;  as  NaCl  (common  salt),Na2SO4  (Glauber's  salt), 
MgSO4  (Epsom  salt) ;  and  even  limestone  (CaCO3)  may  properly 
be  called  a  salt  of  calcium,  and  ferrous  sulfate  (copperas,  which, 
however,  contains  no  copper)  is  a  salt  of  iron  (FeSO^. 

Oxids  and  hydroxids.  As  already  explained,  matter  may  exist 
in  the  form  of  free  elements,  as  nitrogen  (N%) ,  sulfur  (S2) ,  or  phos- 
phorus (P4). 


1 8  SCIENCE  AND   SOIL 

Oxygen  and  hydrogen  are  not  only  very  abundant  elements 
(water,  the  "  universal  solvent,"  being  H2O),  but  they  are  also 
very  active,  chemically,  and  one  or  both  have  some  part  in  nearly 
all  important  groups  of  compounds. 

Oxids  are  binary  compounds  of  oxygen  with  other  elements, 
and  they  constitute  a  very  large  class,  because  almost  all  other 
elements  form  compounds  with  oxygen.  Important  examples 
are  common  quartz  sand,  which  is  silicon  dioxid  (SiO2) ;  water 
itself,  which  is  hydrogen  oxid  (H2O) ;  and  carbon  dioxid 
(CO,). 

Hydroxids  are  compounds  which  always  contain  the  radicle 
— OH,  which  is  known  as  hydroxyl,  or  the  hydroxid  group,  or  the 
hydroxid  radicle.  This  group,  consisting  of  one  atom  of  oxygen 
holding  one  atom  of  hydrogen  with  one  hand  and  with  the  other 
hand  free,  or  clasping  some  other  atom,  is  the  most  important 
group  of  atoms  in  all  chemistry.  As  a  group  it  is  monovalent, 
having  one  free  bond,  and  it  unites  with  almost  all  elements. 
Thus,  we  may  consider: 

Hydrogen  hydroxid,  HOH,  or  water. 
Potassium  hydroxid,  KOH. 
Calcium  hydroxid,  Ca(OH)2. 
Iron  hydroxid,  Fe(OH)3. 
Silicon  hydroxid,  Si(OH)4. 
Phosphorus  hydroxid,  P(OH)5. 
Sulfur  hydroxid,  S(OH)6. 
Ethyl  hydroxid,  C2H5OH,  or  alcohol. 

In  these  compounds,  the  valence  of  the  different  elements  varies 
from  i  to  6,  and  a  corresponding  number  of  hydroxyl  groups 
( — OH)  may  be  held.  While  these  various  hydroxids,  as  KOH,  are 
not  strictly  binary  compounds,  the  unbroken  — OH  group  acts 
much  like  an  element  and  the  ending  -id  is  used  for  these  com- 
pounds. This  cannot  be  misunderstood,  because  potassium  hy- 
droxid (for  example)  plainly  indicates  the  three  elements,  potas- 
sium, hydrogen,  and  oxygen. 

NOTE.  The  meanings  of  a  few  word  endings  and  prefixes  are  noted  here 
for  reference : 


THE  MORE  COMMON  ELEMENTS  AND  COMPOUNDS     19 

The  ending  -ic  means  common,  as  in  ferric  chlorid  (FeCl3),  and  sulfuric 
acid  (H2SO4). 

The  ending  -ous  means  less,  as  less  chlorin,  in  ferrous  chlorid  (FeCk),  and 
less  oxygen,  in  sulfurous  acid  (H2SO3). 

The  ending  -ate  means  common,-  usually  suggests  oxygen,  as  in  sodium 
nitrate  (NaNO3). 

The  ending  -ite  means  less,  as  in  sodium  nitrite  (NaNO2). 

The  prefix  hypo-  means  still  less,  as  in  hyposulfurous  acid  (H2SO2),  or  in 
sodium  hyposulfite  (Na2SO2). 

The  prefix  per-  means  more,  as  in  persulfuric  acid  (H2S2O8). 

The  prefix  hydro-  means  hydrogen  and  no  oxygen,  as  in  hydrochloric  acid 
(HC1). 

The  ending  -ic  in  the  names  of  acids  without  the  prefix  hydro-  suggests 
oxygen,  as  in  sulfuric  acid  (H2SO4). 

The  ending  -id  is  used  for  binary  compounds. 

Hydro-ic  acids  yield  -id  salts;  other  -ic  acids  yield  -ate  salts;  and  -ous 
acids  yield  -ite  salts. 

Hydroxid  oxids.  We  have,  not  only  oxids  and  hydroxids,  but 
also  compounds  that  are  part  oxid  and  part  hydroxid,  as  shown 
by  the  structure  formulas  given  in  the  first  column  in  the  following 
classified  list: 

C1OH  .     .  .  Hypochlorous  acid,  HC1O. 

OC1OH     .  .  Chlorous  acid,  HC1O2. 

O2C1OH   .  .  Chloric  acid,  HC1O3. 

O3C1OH    .  .  Perchloric  acid,  HC1O4. 

S(OH)2    .  .  Hyposulfurous  acid,  H2SO2. 

OS  (OH)  2  .  .  Sulfurous  acid,  H2SO3. 

O2S(OH)2  .  Sulfuric  acid,  H2SO4. 

ONOH     .  .  Nitrous  acid,  HNOa. 

O2NOH    .  .  Nitric  acid,  HNO3. 

Here  we  have  an  atom  of  chlorin,  sulfur,  or  nitrogen,  one  or 
more  oxygen  atoms,  and  also  one  or  more  hydroxyl  groups,  in  the 
same  molecule,  and  the  increasing  valence  of  certain  elements  is 
illustrated,  — that  of  chlorin  from  i  (in  HC1)  to  3,  5,  and  7,  in 
the  compounds  shown;  that  of  sulfur  from  2  (in  H2S  and  CS2) 
to  4  and  6,  in  the  compounds  here  shown;  and  nitrogen  with  three 
and  with  five  bonds. 

The  formulas,  showing  both  oxid  and  hydroxid  characters,  can 


20  SCIENCE   AND   SOIL 

all  be  derived  from  the  corresponding  hydroxids  by  subtracting 
water  (H2O),  thus: 

C1(OH)3  yields  OC1OH  and  H2O. 
C1(OH)5  yields  O2C1OH  and  2  H2O. 
C1(OH)T  yields  O3C1OH  and  3  KjO. 
S(OH)4  yields  OS(OH)2  and  Kp. 
S(OH)6  yields  O2S(OH)2  and  2  KjO. 

(Sulfur  hexahydroxid)  (Sulfuric  acid)  (Water) 

HCK 


\C/ 

0X0H          and 
HO/ 


Acids,  alkalis  (bases),  and  salts.  The  most  important  chemical 
elements  may  be  divided  into  three  great  groups: 

First,  the  six  metals  (iron,  aluminum,  calcium,  magnesium, 
potassium,  sodium);  second,  the  six  nonmetals  (nitrogen,  phos- 
phorus, sulfur,  carbon,  silicon,  chlorin)  ;  and,  third,  the  two  special 
elements,  oxygen  and  hydrogen.  When  combined  with  oxygen  and 
hydrogen,  the  six  metals  form  alkaline,  or  basic,  compounds, 
while  the  six  nonmetals  form  acid  compounds,  as  shown  above. 

Alkali  and  acid  are  exactly  opposite  terms.  An  acid  is  sour, 
while  an  alkali  is  sweet  (chemically  speaking).  A  better  expression 
than  sweet  is  basic,  which  means  the  chemical  opposite  of  sour. 
Thus,  if  the  land  becomes  sour  because  of  the  development  of  acids 
in  the  soil,  we  may  make  it  sweet  by  adding  a  basic  substance 
like  calcium  hydroxid,  Ca(OH)2.  This  compound  is  slacked  lime. 
The  use  of  limestone  and  other  forms  of  lime  for  correcting  soil 
acidity  is  fully  explained  in  the  following  pages. 

Ca(OH)2  and  S(OH)6  are  both  hydroxids,  but  the  first  is  a 
strong  base  (or  alkali)  and  the  other  is  a  strong  acid.  When  they 
are  brought  together,  a  chemical  reaction  occurs  and  the  products 
are  neither  acid  nor  basic,  but  neutral.  The  sulfur  hydroxid 
S(OH)6  may  also  be  called  hexahydroxyl  sulfuric  acid.  It  is  often 
written  H6SO6  but  it  should  be  borne  in  mind  that,  in  the  structure 
of  the  molecule,  oxygen  is  the  middle  link.  If  this  is  heated,  or 


THE  MORE  COMMON  ELEMENTS  AND  COMPOUNDS    21 

made  to  react  with  a  base,  it  first  loses  two  molecules  of  water,  as 
already  shown: 

H6SO6  =  H2SO4  4-  2  H2O. 

The  compound  H2SO4  is  common  sulfuric  acid,  and  it  reacts 
with  calcium  hydroxid  in  accordance  with  the  following  equation : 

/OH"Hl 

Ca< !       4-     !  >S04  =  CaS04  +  2  H2O. 
X!OH     H,!/ 

The  dotted  line  shows  how  the  two  compounds  are  broken.  The 
two  hydrogen  atoms  are  broken  off  from  the  sulfuric  acid  and  the 
two  hydroxyl  groups  are  broken  off  from  the  calcium  hydroxid, 
and  each  hydrogen  atom  (H — )  immediately  joins  hands  with  a 
hydroxyl  group  ( — OH)  and  thus  are  formed  two  molecules  of 
water,  2(H — O — H).  The  bivalent  calcium  atom  (Ca=)  also 
grasps  the  two  free  hands  of  the  radicle  =SO4,  and  forms  the 
compound  CaSO4,  which  is  calcium  sulfate.  Thus,  from  a  base 
(alkali)  and  an  acid,  we  have  formed  water  and  a  neutral  salt, 
neither  acid  nor  alkaline. 

This  is  a  typical  reaction  between  a  hydroxid  acid  and  a  hydroxid 
base,  resulting  in  the  formation  of  a  salt.  Many  other  salts  may  be 
formed  by  similar  reactions  between  basic  hydroxids,  oxids,  or  free 
metals,  on  the  one  hand,  and  different  kinds  of  acids,  on  the  other 
hand,  which  may  contain  oxygen  in  the  form  of  hydroxid  only, 
or  in  both  hydroxid  and  oxid  form,  or  the  acid  may  contain  no 
oxygen,  but  only  hydrogen  joined  directly  to  some  nonmetallic 
element,  as  in  hydrochloric  acid  (HC1)  or  hydrosulf uric  acid  (H2S) . 

Salts  are  the  most  abundant  and  important  compounds.  The 
earth's  crust  consists  largely  of  insoluble  mineral  salts,  called  sili- 
cates. These  are,  as  a  rule,  very  complex  salts,  one  of  the  simplest 
being  common  felspar,  potassium  aluminum  silicate,  KAlSi3O8. 
This  double  salt  is  the  principal  source  of  potassium,  one  of  the 
essential  elements  of  plant  food.  Common  salt  is  sodium  chlorid, 
NaCl.  Epsom  salt  is  magnesium,  sulfate,  MgSO4.  Glauber  salt  is 
sodium  sulfate,  Na2SO4.  Even  limestone  is  a  kind  of  salt,  calcium 
carbonate,  CaCO3. 

For  convenience,  the  formulas  of  salts  containing  oxygen  are 


22  SCIENCE   AND   SOIL 

written  with  the  oxygen  in  one  group,  as  Na^SO^  but  it  may  well 
be  remembered  that  oxygen  is  regularly  the  linking  element  be- 
tween the  metal  and  the  nonmetal,  and  the  structure  of  the  mole- 
cule is  better  shown  if  written  thus: 


A  few  more  equations  for  typical  reactions  will  show  the  various 
ways  by  which  salts  may  be  formed.  Other  similar  acids  and  bases 
give  similar  products: 

Ca(OH)2  +  H2SO4  =  CaSO4  +  2  H2O. 
KOH  +  HNO3  =  KNO3  +  H2O. 

These  equations  represent,  first,  the  reaction  between  the  cal- 
cium hydroxid  and  sulfuric  acid  with  the  formation  of  calcium 
sulfate  (gypsum,  or  land  plaster),  and,  second,  the  reaction  be- 
tween potassium  hydroxid  and  nitric  acid  with  the  formation  of 
potassium  nitrate  (saltpeter). 

In  place  of  a  hydroxid  base,  we  may  use  an  oxid  of  some  metal, 
thus: 

CaO  +  H2SO4  =  CaSO4  4-  H2O. 

CaO  +  2  HNO3  =  Ca(NO3)2  +  H2O. 

K2O  +  H2SO4  =  K2SO4  +  H2O. 

The  salts  formed  are  calcium  sulfate,  calcium  nitrate,  and  potas- 
sium sulfate,  and  in  each  reaction  only  one  molecule  of  water  is 
formed,  when  the  oxid  base  is  used,  in  place  of  two  molecules  of 
water  from  the  use  of  a  bivalent  hydroxid  base. 

The  base  may  be  not  only  in  the  form  of  an  oxid  or  hydroxid  of 
the  metal,  but  we  may  use  the  free  metal  itself  as  a  base,  thus : 

Fe  +  H2SO4  =  FeSO4  +  H2. 

Mg  +  2  HN03  =  Mg(N03)2  +  H2. 

In  these  reactions  the  hydrogen  atoms  are  displaced  by  the  metal 
and  liberated  as  a  gas. 

While  most  acids  contain  oxygen  either  as  a  hydroxid  (C1OH) 
or  a  hydroxid  oxid  (OC1OH  orO2C!OH),  a  few  acids,  with  the  prefix 
hydro-,  contain  no  oxygen;  as,  for  example,  hydrochloric  acid 


THE  MORE  COMMON  ELEMENTS  AND  COMPOUNDS     23 

(HC1);  but  these  acids  also  react  with  bases  (metals,  metallic 
oxids,  or  metallic  hydroxids),  as  shown  above  for  the  oxygen  acids, 
thus: 

Fe  +  2  HC1  =  FeCl2  +  H2. 

CaO  +  2  HC1  =  CaCl2  +  H2O. 

NaOH  +  HC1  =  NaCl  +  H2O. 

In  these  reactions  the  salts  formed  are  chlorids.  The  last  equa- 
tion shows  the  reaction  between  sodium  hydroxid,  which  is  ordi- 
nary concentrated  lye,  a  poisonous  substance,  and  hydrochloric 
acid,  which  is  also  a  poisonous  substance;  and  the  salt  formed  is 
sodium  chlorid  (NaCl),  the  common  table  salt,  and  the  most 
abundant  salt  of  the  ocean. 

Hydrosulfuric  acid  (H2S)  also  forms  many  salts,  called  sulfids, 
as  iron  sulfid  (FeS),  calcium  sulfid  (CaS),  etc. 

In  all  of  these  reactions  the  number  of  pounds  of  any  base  re- 
quired to  react  with  a  given  amount  of  any  acid  is  easily  and  accu- 
rately computed,  and  the  amount  of  the  salt  to  be  formed  and  of 
the  water  or  hydrogen  to  be  liberated  can  also  be  told  in  advance, 
if  one  knows  the  atomic  weights  and  the  equation  for  the  reaction. 
Thus,  40  pounds  of  sodium  hydroxid  will  react  with  36.5  pounds 
of  hydrochloric  acid,  and  form  58.5  pounds  of  common  salt  and 
1 8  pounds  of  water.  It  will  be  seen  that  76.5  pounds  of  materials 
are  used,  and  that  76.5  pounds  of  products  are  formed.  In  like 
manner,  all  such  equations  must  balance.  In  other  words,  the  num- 
ber and  kind  of  atoms  and  the  total  quantity  of  materials  put  into 
the  reaction  oh  one  side  of  the  equation  must  be  exactly  the  same 
as  appear  in  the  products  on  the  other  side  of  the  equation. 

Acid  salts  are  salts  which  still  contain  some  of  the  hydrogen  of 
the  acid  from  which  they  were  made.  Thus,  if  we  supply  only  one 
half  as  much  potassium  as  would  be  required  to  react  with  a  cer- 
tain amount  of  sulfuric  acid,  if  an  acid  salt  is  possible,  it  will  be 
formed: 

KOH  +  H2SO4  =  KHSO4  +  H2O. 

The  sulfuric  acid  molecule  has  two  hydrogen  atoms,  and,  to 
make  neutral  potassium  sulfate,  both  hydrogen  atoms  must  be 
replaced  with  potassium  atoms;  but  in  the  equation  here  shown, 
only  one  potassium  atom  is  provided.  Consequently,  only  one 


24  SCIENCE  AND   SOIL 

hydrogen  atom  is  replaced  by  potassium,  and  the  compound 
formed  is  acid  potassium  sulfate  (HKSO4  or  KHSO4).  The  charac- 
ter of  this  compound  is  one  half  acid  and  one  half  salt.  If  applied 
to  the  soil,  it  would  tend  to  make  the  soil  sour,  or  acid,  which  is  also 
true  of  the  common  acid  phosphate  of  the  fertilizer  trade,  which  is 
further  discussed  under  phosphorus. 

Common  acids  are  so  few  in  number  that  it  is  well  worth  while  to 
memorize  the  formulas.  The  following  are  important  in  the  study 
of  soil  fertility : 

HC1  .  .  .  Hydrochloric  acid  (no  oxygen). 

HNO8  .  .  Nitric  acid. 

HNO2  .  .  Nitrous  acid  (less  oxygen). 

H2SO4  .  .  Sulfuric  acid. 

H3PO4  .  .  Phosphoric  acid. 

H2CO3  .  .  Carbonic  acid. 

H2SiO3  .  .  Silicic  acid. 

H2S  .  .  .  Hydrosulfuric  acid  (no  oxygen). 

The  salts  made  from  these  acids,  and  their  derivatives,  by  reac- 
tion with  the  bases  represented  by  the  six  metals  (iron,  aluminum, 
calcium,  magnesium,  potassium,  and  sodium)  constitute,  in  large 
part,  the  solid  crust  of  the  earth  and  the  salts  of  the  sea.  One  non- 
metallic  oxid  (SiO,j)  and  two  oxids  of  metallic  elements  (Fe2O3  and 
ALjO3)  are  also  found  native  in  very  considerable  amounts. 

Some  acids  are  strong  and  some  are  weak.  The  weakest  acid  is 
carbonic  (H2CO3),  but  silicic  (H2SiOg)  and  hydrosulfuric  (H2S) 
are  also  weak  acids;  while  hydrochloric  (HC1),  nitric  (HNOg), 
sulfuric  (H2SO4),  and  phosphoric  (HgPOJ  are  all  very  strong  acids. 
A  strong  acid  may  take  a  base  away  from  a  weak  acid,  thus : 

CaCO8  +  H2SO4  =  CaSO4  +  H2CO8. 

Here  we  have  the  strong  sulfuric  acid  reacting  with  calcium 
carbonate  (limestone)  to  form  a  neutral  salt,  calcium  sulfate,  and 
the  weak  carbonic  acid.  The  carbonic  acid  is  so  weak  that  it  may 
break  in  two,  forming  water  and  carbon  dioxid: 

H2CO3  =  H2O  +  CO2. 


THE  MORE  COMMON  ELEMENTS  AND   COMPOUNDS    25 

Thus  we  may  apply  limestone  (CaCO3)  to  an  acid  soil  (containing 
organic  acids,  silicic  acid,  or  acid  silicates) ,  and  the  soil  acids  will 
take  the  base  (calcium),  and  the  liberated  carbonic  acid  will  break 
in  two,  the  gas  carbon  dioxid  (CO2)  passing  out  of  the  soil  into  the 
air  and  thus  leaving  the  soil  with  no  acid  in  it. 


CHAPTER  III 

PLANT  FOOD  AND  PLANT  GROWTH 

Oxygen.  Oxygen  is  the  most  abundant  element.  It  constitutes 
about  one  half  the  sum  of  all  known  matter.  It  forms  chemical 
compounds  with  nearly  all  other  elements,1  and  is,  in  consequence, 
termed  a  chemically  active  element.  In  the  free  state  (O2),  it  is  a 
gas.  In  this  form  it  constitutes  about  23  per  cent  of  the  air.  It 
is  thus  present  everywhere  and  ready  to  form  compounds  with  other 
elements,  or  to  attack  other  compounds  under  favorable  conditions. 
The  compounds  formed  with  oxygen  may  at  ordinary  temperatures 
be  gases,  such  as  carbon  dioxid  (CO2) ,  liquids,  such  as  water  (H2O) , 
solids,  such  as  iron  oxid  (Fe^Og). 

All  ordinary  combustion  consists  of  chemical  reaction  with 
oxygen,  and  the  principal  products  formed  are  carbon  dioxid  and 
water. 

Water  is  eight  ninths  oxygen,  and  carbon  dioxid  is  eight 
elevenths  oxygen,  as  any  one  can  determine  for  himself  if  he  knows 
the  atomic  weights  given  in  Table  2.  The  grain  of  corn  is  nearly 
one  half  oxygen  (46  per  cent). 

Carbon.  This  is  -a  very  common  element,  but  not  very  abundant 
as  compared  with  nine  other  elements.  Even  titanium,  a  tetrava- 
lent  element  belonging  to  the  same  periodic  group  as  carbon  and 
silicon,  is  one  half  more  abundant  than  carbon  in  the  earth's  crust. 
But  titanium  has  no  agricultural  value,  while  carbon  is  one  of 
the  most  important  elements  in  the  structure  of  plants  and  ani- 
mals. About  45  per  cent  of  the  corn  kernel  is  carbon. 

Carbon  in  the  free  state  is  the  principal  element  in  coal  and  char- 
coal. Soft  coal  (bituminous)  contains  about  90  per  cent  of  carbon, 
and  hard  coal  (anthracite)  contains  about  97  per  cent  of  carbon. 

Graphite,  the  "  lead  "  used  in  lead  pencils,  is  not  lead,  but  car- 

1  No  oxygen  compounds  are  known  with  fluorin,  argon,  or  helium. 

26 


PLANT   FOOD   AND   PLANT    GROWTH  27 

bon.  It  differs  in  some  manner  from  the  carbon  in  coal  or  char- 
coal, probably  because  of  a  different  number,  or  a  different  arrange- 
ment, of  the  atoms  in  the  molecule. 

The  diamond  is  very  pure  carbon  in  crystallized  form.  Both  the 
diamond  and  ordinary  carbon  may  be  converted  into  graphite, 
and  small  diamonds  have  been  made  artificially  from  ordinary 
carbon. 

Free  carbon  in  any  form  burns  with  oxygen  to  form  carbon  dioxid 
(CO2),  but  with  graphite  and  the  diamond  the  reaction  occurs 
only  at  higher  temperatures  than  are  necessary  with  ordinary 
carbon. 

Carbon  in  the  free  state  has  never  been  liquefied,  but  it  has 
been  volatilized  at  the  temperature  of  3500°  Centigrade  (6332° 
Fahrenheit).  On  the  other  hand,  many  of  the  compounds  with 
carbon  are  liquids  or  gases  at  ordinary  temperatures.  Examples 
of  liquid  compounds  are  carbon  disulfid  (CS2),  benzene  (C6H6),  and 
many  other  hydrocarbons  contained  in  petroleum;  while  carbon 
dioxid  (CO2)  ,  methane  (CH^)  ,  and  acetylene  (C^Hg)  are  well-known 
gases  containing  carbon. 

In  the  solid  form,  carbon  occurs  not  only  in  the  free  state, 
but  also  in  compounds,  of  which  two  very  important  groups  are 
the  carbonates  and  the  carbohydrates.  Marble,  limestone,  chalk, 
and  marl  are  different  forms  of  calcium  carbonate  (CaCO3),  one 
of  the  few  compounds  with  a  molecular  weight  of  100,  and  thus 
containing  12  per  cent  of  carbon,  40  per  cent  of  calcium,  and  48 
per  cent  of  oxygen.  Of  these  four  materials  marble  is  nearly  pure 
calcium  carbonate,  while  the  others  may  be  nearly  pure  or  very 
impure.  When  calcium  carbonate  is  heated,  two  bonds  are  broken 
and  then  joined  in  another  way,  so  that  the  one  compound  (CaCO3) 
is  broken  into  two  (CaO)  and  (CO2),  thus: 


=O   becomes   Ca:  =  O,  or 


CaCO8  =  CaO  +  CO2. 


The  calcium  oxid  (CaO)  is  burned  lime,  or  quicklime,  which 
remains  in  the  kiln;  while  carbon  dioxid  (CO2)  is  a  gas  which  passes 
off  into  the  air.  It  is  easy  to  see  that  only  56  pounds  of  quicklime 
could  be  made  from  100  pounds  of  pure  limestone. 


28  SCIENCE  AND    SOIL 

Limestone  is  a  constituent  of  good  soils,  and  if  limestone  is  not 
present  in  a  soil,  then  it  should  be  applied;  for,  as  already  explained, 
carbonic  acid  is  the  weakest  of  all  acids,  and,  consequently,  if  the 
soil  contains  limestone,  it  cannot  be  an  acid  soil,  because  the  soil 
acids  will  take  the  base  away  from  calcium  carbonate  (and  also 
from  any  other  carbonate),  and  the  liberated  carbonic  acid  is 
broken  up  into  water  and  carbon  dioxid. 

Magnesium  carbonate  and  iron  carbonate  are  found  in  rock 
deposits;  while  potassium  carbonate  (K2COg)  is  the  lye  (alkali) 
obtained  from  wood  ashes,  and  sodium  carbonate  (Na2COg)  is  the 
most  harmful  alkali  in  alkali  soils.  The  carbonic  acid  is  so  weak 
that  the  carbonates  of  the  strongest  bases  (potassium  and  sodium) 
are  almost  as  basic  (alkaline)  as  the  hydroxids  of  the  same  ele- 
ments (KOH  and  NaOH). 

The  term  hydrate  used  in  the  name  of  a  chemical  compound 
means  that  it  contains  water  combined  with  some  other  constitu- 
ent, or  that  hydrogen  and  oxygen  are  present  in  the  same  propor- 
tion as  in  water  (H2O).  Thus,  carbohydrates  contain  carbon  and 
water.  This  very  important  group  of  carbon  compounds,  includ- 
ing sugar,  starch,  and  cellulose  (wood  fiber)  will  be  explained  after 
hydrogen  has  been  discussed. 

Hydrogen.  Hydrogen  is  the  third  most  important  element  in 
plants,  constituting  about  6.4  per  cent  of  the  corn  kernel.  Water 
is  the  only  abundant  source  of  hydrogen,  although  the  element  is 
found  in  the  earth's  crust  in  appreciable  amount,  chiefly  in  hy- 
drated  mineral  compounds  containing,  as  the  name  indicates, 
water  in  combination  with  salts.  In  some  cases  the  combined 
water  corresponds  to  the  amount  that  might  be  held  in  hydroxid 
form;  as,  for  example,  in  the  abundant  mineral  called  gypsum, 
or  land  plaster,  which  is  calcium  sulfate  crystallized  with  two 
molecules  of  water,  CaSO4  :  2  H2O,  or  CaO2S(OH)4. 

Hydrogen  in  the  free  state  (H2)  is  a  gas.  From  Table  i  it  will  be 
seen  that  the  molecule  of  hydrogen  (H^  is  lighter  than  the  atom  of 
any  other  element;  and,  according  to  the  gas  law,  a  given  volume 
will  be  filled  by  the  same  number  of  molecules  of  hydrogen  as  of 
any  other  gas.  Consequently,  hydrogen  gas  is  the  lightest  of  all 
known  gases,  so  that  a  balloon  filled  with  hydrogen  easily  floats 
in  the  atmosphere  of  nitrogen  (N.j)  and  oxygen  (O2),  one  of  which 


PLANT   FOOD   AND   PLANT   GROWTH  29 

is  fourteen  times,  and  the  other  sixteen  times,  heavier  than  hy- 
drogen. 

At  the  ordinary  temperature,  hydrogen  and  oxygen  gases  can 
be  mixed  together  and  remain  a  mixture;  but,  if  heated  or  ignited, 
the  bonds  which  hold  the  atoms  in  molecules  (H2  and  Og)  are 
broken,  and  the  mixture  explodes  with  terrific  force  and  loud  re- 
port. The  only  product  of  the  explosion,  or  at  least  of  the  reac- 
tion, is  water,  H2O;  and,  if  either  gas  was  present  in  the  mixture 
in  excess  of  these  proportions,  the  excess  remains  unchanged. 
The  corn  kernel  contains  6.4  per  cent  of  hydrogen,  or  about  97^ 
per  cent  of  the  three  elements,  oxygen,  carbon,  and  hydrogen. 

Life.  The  fixation  of  carbon  is  the  most  important  process  in  the 
growth  of  plants.  By  the  term  fixation  is  meant  the  changing  of  a 
gas  or  soluble  substance  to  a  solid  or  insoluble  form  by  means  that 
involve  chemical  reaction.  (The  fixation  of  atmospheric  nitrogen, 
the  fixation  of  soluble  phosphorus  in  soils,  and  the  fixation  of  po- 
tassium and  other  bases  will  be  explained  in  the  following  pages.) 

The  process  known  as  the  fixation  of  carbon  is  the  more  impor- 
tant, because  it  involves,  not  only  the  fixation  of  carbon  itself, 
but  likewise  the  fixation  of  both  oxygen  and  hydrogen.  Its  im- 
portance is  better  appreciated  by  recalling  that  these  three  ele- 
ments compose  about  95  per  cent  of  the  entire  weight  of  most 
agricultural  plants  or  crops.  Both  the  carbon  and  oxygen  utilized 
in  plant  growth  are  derived  from  the  carbon  dioxid  contained  in 
the  air.  It  is  truly  remarkable  that  90  per  cent  (90  pounds  in  100) 
of  our  common  crops  must  be  secured  from  .04  per  cent  (4  parts  in 
10,000)  of  the  air. 

The  fixation  of  carbon,  oxygen,  and  hydrogen  takes  place  in  the 
green  parts  of  plants.  The  carbon  dioxid  enters  through  the  breath- 
ing pores l  on  the  under  side  of  the  leaf;  and  the  water,  composed 

1  A  breathing  pore  consists  of  two  guard  cells  with  a  slit  between  them,  passing 
through  the  outer  coat  of  the  leaf.  These  slits  or  openings  are  greatly  influenced 
by  the  moisture  and  temperature  of  the  air.  In  the  absence  of  light  they  remain 
closed.  When  the  breathing  pores  are  open,  the  outside  air  has  free  access  to  the 
intercellular  spaces  and  passages  within  the  leaf. 

The  number  of  breathing  pores  varies  with  different  plants,  ^.bout  17,000  per 
square  inch  have  been  found  on  oat  leaves,  102,000  on  corn  leaves,  and  216,000 
per  square  inch  on  the  leaves  of  red  clover.  They  are  found  chiefly  on  the  under  side 
of  leaves  and  on  green  stems,  but  sometimes  in  small  numbers  on  the  upper  leaf 
surface  and  even  on  underground  stems. 


30  SCIENCE   AND   SOIL 

of  hydrogen  and  oxygen,  enters  the  leaf  through  the  stem,  having 
passed  from  the  soil  into  the  plant  through  the  roots. 

As  the  carbon  dioxid  and  water  come  together  within  the  leaf,  a 
chemical  reaction  occurs  which  may  be  illustrated  by  the  following 
equation: 

H2=o  +;o=c=o  =  H2co  +  oa. 


The  dotted  line  shows  how  the  bonds  are  broken.  The  two  atoms 
of  oxygen  that  are  set  free  immediately  join  hands  to  form  a  mole- 
cule of  oxygen  (O2),  which  passes  from  the  leaf  into  the  outer  air. 
The  two  hydrogen  atoms  (H2=)  attach  themselves  to  the  group, 
=CO,  forming  the  compound,  H2CO,  which  may  also  be  written 
CH2O,  to  show  its  hydrate  character,  and  which  might  be  called 
monose,  but  is  commonly  known  as  formic  aldehyde.  This  reac- 
tion occurs  only  in  the  light  and  only  in  the  presence  of  active 
living  chlorophyll  (the  green  coloring  matter  of  leaves).  In  other 
words,  this  compound  is  formed  under  the  influence  of  life,  and 
by  it  we  enter  a  new  field  known  as  organic  chemistry. 

Organic  matter.  Organic  matter  consists  of  compounds  formed 
by  life  processes,  — compounds  that  are,  or  have  been,  living 
matter;  whereas,  inorganic  matter  consists  of  rocks,  minerals,  and 
metals,  of  salts,  liquids,  and  gases,  whose  origin  has  no  necessary 
connection  with  any  living  substance.  Organic  matter  consists 
of  carbon  compounds,1  such  as  hydrocarbons  (containing  only 
hydrogen  and  carbon) ,  fats  (containing  much  carbon  and  hydrogen 
with  little  oxygen),  carbohydrates  (containing  carbon  with  hy- 
drogen and  oxygen  in  proportion  to  form  water  —  as  the  name  in- 
dicates), and  proteids,  which  contain  not  only  carbon,  hydrogen, 
and  oxygen,  but  also  nitrogen,  and  sometimes  phosphorus  and 
sulfur.  These  are  the  great  groups  of  organic  compounds  compos- 
ing plants  and  animals.  The  carbohydrates  are  the  most  abundant 
in  plants,  while  the  proteids,  although  a  necessary  part  of  plants, 
are  the  most  abundant  compounds  in  animals. 

Aldehydes  and  carbohydrates.  Formic  aldehyde  is  only  one  of 
many  aldehydes,  which  constitute  a  large  class  or  series  of  organic 
compounds.  The  aldehydes  are  extremely  active  substances  and 

1  Many  of  the  simpler  carbon  compounds  can  be  made  artificially. 


PLANT   FOOD   AND    PLANT    GROWTH  31 

have  power  to  attack  and  decompose  other  substance.  Formic 
aldehyde  is  often  used  as  a  disinfectant,  and  a  40  per  cent  solution, 
known  as  "  formalin,"  is  employed  (at  the  rate  of  one  pound  of 
formalin  in  50  gallons  of  water)  to  destroy  smut  in  seed  oats,  for 
example. 

A  remarkable  property  of  the  aldehydes  is  the  power  of  condensa- 
tion, by  which  two  or  more  molecules  are  condensed  into  one. 
Thus,  two  molecules  of  formic  aldehyde,  or  monose,  2  CH2O,  may 
become  one  molecule  of  diose,  C2H4O2;  while  three  molecules  may 
form  one  of  triose,  C3H6O3;  and  four  may  form  tetrose,  C4H8O4; 
and  five,  pentose,  C5H10O5;  etc. 

The  condensation  process  is  so  rapid  that  formic  aldehyde  itself 
is  found  in  plants  only  in  very  small  amount,  while  the  condensa- 
tion products  constitute  commonly  80  to  90  per  cent  of  the  entire 
plant.  The  ending  -ose  means  sugar,  and  the  prefix  mon-,  di-,  tri-, 
etc.,  designate  the  number  of  carbon  atoms  in  the  molecule.  The 
following  may  illustrate  this  series  of  carbohydrates: l 

CH2O,  monose  (formic  aldehyde). 
C2H4O2,  diose  (unknown). 
C3H6O3,  triose  (glycerose). 
C4H8O4,  tetrose  (erythrose). 
C5H10O5,  pentose  (xylose). 
C6H12O6,  hexose  (glucose). 
£-12^240 12,  lactose  (milk  sugar). 
C^HjgOy,  sucrose  (common  sugar). 

Here  we  may  see  the  possible  development  of  the  well-known 
glucose,  milk  sugar,  and  common  sugar  (obtained  from  sugar  cane 
and  sugar  beets),  as  condensation  products  from  monose,  or  formic 
aldehyde,  formed  in  the  living  plant  from  carbon  dioxid  and  water. 

1  It  cannot  be  considered  as  absolutely  proven  that  formic  aldehyde  is  always 
the  first  product  of  this  fixation  process;  and,  if  it  is,  it  seems  that  the  first  condensa- 
tion product  results  from  the  union  of  three  molecules,  because  the  compound 
that  might  be  called  diose  is  not  found  in  plants  and  is  not  known  to  exist. 

The  known  facts  are  that  carbon  dioxid  is  condensed  in  the  leaves  of  plants 
and  that  oxygen  is  given  off  in  the  proportions  required  for  this  reaction  (aside  from 
the  oxygen  normally  exhaled),  also  that  formic  aldehyde  is  found  in  plant  leaves, 
that  aldehydes  have  the  power  of  condensation,  and  that  multiples  of  the  formic 
aldehyde  molecule  are  actually  present  in  plants  (as  hexose)  or  represented  (as 
in  starch,  cellulose,  pentosans,  etc.). 


32  SCIENCE  AND    SOIL 

It  may  be  noted  that  cane  sugar  differs  from  milk  sugar  by  one 
molecule  of  water  (HgO) .  The  sugars  are  a  very  important  group 
of  compounds,  but  perhaps  the  starches  are  a  still  more  important 
group.  Starch  (C6H10O6)  appears  to  differ  from  glucose  (C6H12O6)  by 
one  molecule  of  water  (H2O) ,  but  it  is  known  that  the  starch  mole- 
cule is  not  simply  C6H10O5,  but  some  multiple  of  this  formula,  which 
is  best  written  (C6H10O6)^,  in  which  x  stands  for  the  number  by 
which  this  formula  should  be  multiplied,  for  as  yet  x  is  unknown, 
although  the  proportion  or  percentage  of  each  element  in  starch 
is  known. 

The  formula  for  cellulose  (plant  fiber)  must  also  be  recorded  as 
(CgHjoOg)^.,  but  this  x  may  be  a  different  number  than  the  x  of 
the  starch  molecule. 

Growth.  Rapidity  of  growth  is  related  to  leaf  surface.  Sugar, 
starch,  and  fiber  constitute  the  great  carbohydrate  group  of  plant 
structure,  and  their  formation  is  dependent  primarily  upon  the 
fixation  of  carbon,  with  oxygen  and  hydrogen,  in  the  leaf; .  and, 
with  all  necessary  things  provided  in  proportionate  amounts,  this 
process  goes  on  in  direct  proportion  to  leaf  surface.  In  other  words, 
under  perfect  conditions,  a  leaf  four  inches  long  will  grow  four  times 
as  much  during  the  day  as  a  leaf  only  one  inch  long;  and,  with 
sufficient  moisture  and  with  plant  food  provided  in  abundance, 
a  pasture  with  the  grass  kept  six  inches  long  will  furnish  twice 
as  much  feed  as  one  with  the  grass  kept  down  to  three  inches. 

If  the  foundation  principles  and  the  controlling  factors  in  plant 
growth  can  be  known,  then  the  ideal  conditions  for  crop  production 
may  be  provided  much  more  nearly  than  is  common.  The  ideal 
condition  is  to  provide  all  controllable  factors  in  such  abundance 
or  perfection  that  the  crop  yields  will  be  limited  only  by  the  sun- 
shine and  rainfall.  With  all  other  limiting  factors  removed,  the 
average  yield  of  corn  in  the  corn  belt  would  undoubtedly  exceed 
ico  bushels  per.  acre.  (See  the  records  of  actual  yields,  in  the  follow- 
ing pages.) 

Carbon  cycle.  The  carbon  cycle  includes  both  the  fixation  and 
the  liberation  of  carbon.  Animals  feed  upon  plants  and  plant  prod- 
ucts rich  in  carbon  compounds,  which  in  part  are  digested  and  car- 
ried into  the  blood  to  meet  the  oxygen  inhaled  through  the  lungs. 
The  carbon  is  burned,  or  oxidized,  to  carbon  dioxid,  furnishing 


PLANT   FOOD   AND   PLANT   GROWTH  33 

to  the  animal  the  energy  or  heat'  equivalent  to  that  of  ordinary 
combustion  in  the  furnace,  of  the  same  materials;  and  the  carbon 
dioxid  is  then  thrown  off  through  the  lungs  into  the  air,  again  to 
become  the  source  of  carbon  and  oxygen  for  plants.  Thus,  the 
fixation  of  carbon  by  the  plants  on  the  one  side,  and,  on  the  other, 
all  forms  of  combustion,  including  the  visible  flame,  the  consump- 
tion and  oxidation  of  food  by  animals,  or  the  oxidation  of  organic 
matter  in  the  soil,  completes  the  endless  carbon  cycle. 

But  for  this  carbon  cycle,  plant  growth  and  crop  production 
would  soon  cease.  A  simple  computation  reveals  facts  not  com- 
monly appreciated : 

A  column  of  air  one  inch  square  and  the  height  of  the  atmosphere 
weighs  15  pounds,  which  is  equivalent  to  2160  pounds  per  square 
foot,  or  less  than  95  million  pounds  per  acre.  In  ten  thousand 
pounds  of  average  air  there  is  less  than  four  pounds  of  carbon 
dioxid  (CO2)  or  about  one  pound  of  carbon.  Consequently,  there  is 
less  than  10,000  pounds  of  carbon  in  the  air  above  one  acre  of  land. 
In  loo  bushels  of  corn  (5600  pounds),  there  are  2500  pounds  of 
carbon.  (See  Table  2,  or  compute  from  the  per  cent  of  carbon  in 
starch  and  fiber,  C6H10O5.)  Thus,  the  total  supply  of  carbon  over 
an  acre  of  land  is  only  equal  to  the  needs  of  four  such  corn  crops  as 
are  commonly  produced  on  the  best-treated  corn-belt  land  in  the 
best  seasons,  the  grain  only  being  considered,  or  to  only  two  crops, 
considering  both  grain  and  stalks.  If,  however,  only  one  fourth 
of  the  earth's  surface  is  land,  if  only  one  fourth  of  the  land  is 
cropped,  and  if  only  one  fourth  of  100  bushels  is  the  average  crop, 
then  the  supply  of  carbon  is  sufficient,  not  for  two  years  only,  but 
for  128  years,  which,  however,  still  emphasizes  the  fact  that  the 
carbon  cycle  makes  possible  the  continuation  of  plant  life  on  the 
earth. 

A  maintenance  ration  for  animals  is  a  supply  of  food  sufficient 
only  to  support  the  animal  body  in  health,  to  provide  food  materials 
for  repairing  the  daily  waste,  and  to  furnish  energy  sufficient  to 
keep  the  body  warm  and  to  maintain  the  circulation  of  the  blood 
and  other  necessary  activities.  Plants  also  have  some  vital  pro- 
cesses to  provide  for,  and,  to  a  limited  extent,  plants  are  consumers 
of  energy  day  and  night.  Food  materials  are  stored  by  the  plant, 
chiefly  to  be  utilized  in  subsequent  plant  development.  Thus 


34  SCIENCE  AND   SOIL 

sugars  are  converted  into  starch  and  stored  away  in  roots,  tubers, 
or  seeds,  to  supply  the  future  needs  of  the  same  plant  or  of  new 
plants.  At  the  proper  time  the  plant  reconverts  the  insoluble 
starch  into  soluble  sugar  1  and  carries  it  through  the  circulation 
to  the  point  of  consumption  as  food  by  the  plant,  either  for 
energy,  repair,  or  growth.  Food  materials  are  thus  consumed  or 
oxidized  within  the  plant,  and  carbon  dioxid  is  constantly  given 
off  from  all  its  living  parts,  including  the  roots.  During  the  day 
the  fixation  of  carbon  is  commonly  so  great  as  to  completely  mask 
the  liberation  of  carbon  dioxid  in  the  green  parts  of  the  plant. 

Vegetable  fats.  Before  leaving  the  subject  of  the  fixation  of 
carbon,  oxygen,  and  hydrogen,  some  further  mention  should  be 
made  of  the  group  of  compounds  called  fats,  whose  importance  is 
exceeded  only  by  that  of  carbohydrates  and  protein. 

The  vegetable  fats  and  oils  show  distinct  relationship  to  a  con- 
densation process  similar  to  the  formation  of  sugars  and  other 
carbohydrates  from  formic  aldehyde,  the  photosynthetic  product  of 
the  reaction  between  carbon  dioxid  and  water  in  the  leaves  of 
plants.  The  following  series  of  compounds  will  show  this  relation- 
ship: 

HYDROCARBONS  FATTY  ACIDS 

HCH3—  Methane     ........  HCOOH  —  Formic  acid. 

CH3CH3—  Ethane    ........  CH3COOH—  Acetic  acid. 

C2HSCH3  —  Propane      .......  C2H5COOH  —  Propionic  acid. 

C3H7CH3  —  Butane  ........  C3H7COOH  —  Butyric  acid. 

C4H9CH3  —  Pentane  ........  C4H9COOH  —  Valeric  acid. 

C5HUCH3  —  Hexane      .......  C5HUCOOH  —  Hexoic  acid. 

C6H13CH3  —  Heptane     .......  C6H13COOH  —  Heptoic  acid. 

C7H15CH3  —  Octane  ........  C7H15COOH  —  Octoic  acid. 

CnH23CH3  —  Dodecane  .......     CnH^COOH  —  Laurie  acid. 

C15H31CH3—  Hecdecane     ......     C15H31COOH  —  Palmitic  acid. 

C17H35COOH  —  Stearic  acid. 

—  Oleic  acid. 
Unsaturated    ........  C17H31COOH  —  Linolic  acid. 

—  Linolenic  acid. 


The  hydrocarbons,  which  constitute  the  simplest  series  of  carbon 
compounds,  are  shown  for  direct  comparison  with  the  fatty  acid 

1  Glucose  sugars  and  sirups  are  manufactured  in  large  quantities  by  use  of  strong 
acids  for  converting  the  starch  into  glucose. 


PLANT   FOOD    AND   PLANT    GROWTH  35 

series.  All  of  the  compounds  here  illustrated  are  known.  The  two 
series  differ  only  by  the  — COOH  group  in  the  fatty  acid  series  in 
place  of  the  — CH3  group  in  the  hydrocarbon  series.  The  — CH3 
group  is  methane  from  which  one  hydrogen  atom  is  removed, 
leaving  the  radicle  — CH3,  which  is  called  methyl  (one  of  the  alkyl 
radicles),  and  acts  as  a  monovalent  radicle,  replacing  one  hydrogen 
atom.  It  finds  a  place  in  many  organic  compounds,  as  in  ethane 
(CH3— CH3),  butane  (CH3— CH2— CH2— CH3) ,  etc. 

The  group,  — COOH,  is  called  carboxyl,  or  the  acid  group.  It 
may  be  represented: 

—  C— O  — H 

II 
O 

This  group  also  has  one  free  bond  and  acts  as  a  monovalent 
radicle.  Whenever  this  group  is  contained  in  an  organic  compound, 
the  compound  is  an  acid.  The  hydrogen  in  the  hydroxyl  part  of 
this  group  may  be  replaced  by  metals,  thus  forming  salts.  If  the 
free  hand  in  this  carboxyl  group  is  grasped  by  a  hydrogen  atom,  the 
compound  formed  is  formic  acid,  but  if  methyl  ( — CH3)  joins  hands 
with  carboxyl  ( — COOH),  the  compound  formed  is  acetic  acid 
(CH3COOH) ,  the  acid  which  gives  to  vinegar  its  sour  taste.  When 
lead  (Pb)  is  used  as  a  base  to  form  a  salt  with  acetic  acid  by  re- 
placing the  acid  hydrogen  of  the  hydroxyl  group,  the  sourness  is 
destroyed  and  the  salt  is  known  as  sugar  of  lead,  or  lead  acetate, 
(CH3COO)2Pb.  When  the  hydroxyl  group  joins  alkyl  radicles 
( — CH3,  — C2H5,  etc.),  alcohols  are  formed,  as  methyl  alcohol 
(CH3OH),  called  wood  alcohol,  and  ethyl  alcohol  (C2H6OH), 
which  is  common  alcohol. 

Common  glycerin,  which  is  also  called  glycerol  (because  it  is 
an  alcohol),  is  an  organic  compound  consisting  of  a  trivalent 
radicle,  called  glyceryl,  united  with  three  hydroxyl  groups, 
C3H5(OH)3. 

Common  animal  fats  consist  chiefly  of  palmitic,  stearic,  and  oleic 
acids  combined  with  this  radicle,  =C3H5,  and  the  fats  themselves 
are  called  palmitin,  stearin,  and  olein.  The  harder  fats,  like  tallow, 
contain  more  stearin  (C17H35COO)3C3H5,  while  the  softer  fats,  like 
lard  and  butter,  contain  considerable  olein,  which  differs  from 


36  SCIENCE  AND   SOIL 

stearin  by  having  two  less  hydrogen  atoms  in  each  acid  radicle. 
By  itself,  olein  is  a  liquid  or  oil. 

The  oil  of  corn  contains  about  4  per  cent  of  stearin,  45  per  cent 
of  olein,  and  48  per  cent  of  linolin,  which  differs  from  olein  by  two 
hydrogen  atoms,  and  from  stearin  by  four  hydrogen  atoms,  in 
each  acid  radicle. 

When  these  fats  and  oils  are  heated  with  a  strong  base  (alkali) 
such  as  potassium  hydroxid,  three  potassium  atoms  displace 
the  glyceryl  radicle  (=C3H5)  and  form  potassium  stearate 
(C^H^COOK),  potassium  oleate  (C17H33COOK),  etc.;  while 
the  three  hydroxyl  groups  unite  with  glyceryl  to  form  glycerin, 
C3H5(OH)3.  The  salts  formed  by  potassium  or  sodium  with  these 
fatty  acids  are  what  we  call  soap,  the  potassium  compounds  being 
soft  soap,  and  the  sodium,  hard  soap. 

While  the  fixation  of  carbon,  oxygen,  and  hydrogen,  resulting 
ultimately  in  the  formation  of  carbohydrates  and  fats,  is  properly 
considered  the  most  important  process  in  plant  growth,  we  may 
well  remember  that  no  fixation  and  no  growth  occur  in  the  absence 
of  the  other  seven  essential  elements  of  plant  food.  Indeed,  from 
the  standpoint  of  possible  control  of  crop  production,  another 
tripod  is  more  important  than  these  three;  namely,  nitrogen, 
phosphorus,  and  limestone. 

Nitrogen.  This  element  has  received  more  consideration  as 
plant  food  than  any  other  essential  element.  In  the  free  state  (Ng) 
it  is  a  gas,  and  in  this  form  it  constitutes  three  fourths  of  the  air. 
The  total  supply  of  nitrogen  over  each  acre  of  the  earth's  surface, 
if  available,  would  meet  the  needs  of  a  hundred-bushel  crop  of 
corn  every  year  for  500,000  years;  whereas  the  supply  of  carbon 
is  sufficient  for  such  crops  for  only  two  years.  Nevertheless,  carbon 
has  no  commercial  value  as  plant  food,  while  nitrogen  in  available 
form  is  worth  15  to  20  cents  a  pound  in  the  markets.  These  facts 
only  emphasize  the  need  of  science  in  agriculture. 

Nitrogen  is  not  contained  in  the  mineral  matter  of  the  earth,  but 
it  is  a  constituent  of  common  organic  matter.  It  is  an  essential 
part  of  the  structure  of  every  plant  and  animal,  and  is  present  in  all 
crops  and  crop  residues  and,  consequently,  in  the  organic  matter, 
vegetable  matter,  or  humus,  of  the  top  soil;  and  it  is  from  the 
decomposition  products  of  this  organic  matter  that  nitrogen  is 


PLANT   FOOD   AND    PLANT   GROWTH  37 

furnished  to  most  growing  crops,  by  a  process  (nitrification)  that 
is  more  fully  explained  in  the  following  pages. 

Protein.  Protein  is  the  general  name  for  organic  nitrogen  com- 
pounds, including  the  proteids,  or  final  products,  and  the  amids, 
or  intermediate  products.  The  amids  and  proteids  of  the  protein 
group  might  be  compared  with  the  sugars  and  starches  (and  fibers) 
of  the  carbohydrate  group  in  which  the  sugars  are  the  intermediate 
form  and  the  starches  (and  fibers)  the  more  permanent  form. 
Protein  always  contains  nitrogen  in  addition  to  oxygen,  carbon, 
and  hydrogen. 

The  chemical  reactions  involved  in  the  formation  of  proteids 
are  not  yet  well  understood,  although  many  of  the  intermediate 
products  (amids)  are  well  known,  and  some  can  be  made  arti- 
ficially. The  amids  are  especially  abundant  in  young  or  immature 
plants,  and  they  are  also  liberated  as  intermediate  decomposition 
products.  Thus,  carbamid,  O=C=(NH2)2,  which  is  also  called 
urea,  is  a  common  nitrogen  compound  in  urine,  the  medium  by 
which  most  of  the  nitrogen  waste  is  thrown  off  from  the  animal 
body.  This  compound  might  be  considered  as  formic  aldehyde,  or 
monose  (O=C  =  H2),  in  which  the  two  hydrogen  atoms  are  re- 
placed by  two  amido  groups,  and  the  amido  group  ( — NH2)  may 
be  considered  as  ammonia  in  which  only  two  monovalent  hydrogen 
atoms  are  joined  to  the  trivalent  nitrogen  atom,  thus  leaving  one 
free  hand  by  which  this  group  may  be  attached  to  other  groups  or 
atoms  in  the  building  of  molecules.  The  hydroxyl  group  ( — OH) 
and  water  (OH2),in  relation  to  oxygen,  correspond  to  the  amido 
group  ( — NH2)  and  ammonia  (NH3),  in  relation  to  nitrogen,  and 
also  to  the  methyl  group  ( — CH3)  and  methane  (CH^,  in  relation  to 
carbon.  The  amido  group  ( —  NH2)  acts  as  a  monovalent  radicle, 
and  by  replacing  hydrogen  atoms  in  various  compounds  forms  new 
compounds  called  amids,  or  amido  compounds,  and  these  by  con- 
densation or  combination  with  other  groups  may  form  the  final 
nitrogenous  organic  compounds  called  proteids,  which  constitute 
chiefly  the  flesh  (not  fat)  and  vital  organs  of  animals,  and  the  pro- 
tein of  mature  plants. 

It  has  been  suggested  that  amido  formic  aldehyde,  H2NCHO,  or 
amido  acetic  aldehyde,  CH2(NH2)CHO,  or  aspartic  aldehyde  (see 
aspartic  acid  and  asparagin  in  the  following  list)  may  furnish  the 


38  SCIENCE  AND   SOIL 

initial  molecules  whose  condensation  produces  proteids,  but  this 
is  largely  speculative. 

The  following  list  illustrates  some  instructive  relationships  of 
important  and  well-known  compounds: 

HCOOH,  or  H—  C—  OH  ....     Formic  acid. 

II 

O 
CH8COOH,  or  H3=C—  C—  OH  .     .     Acetic  acid  (the  acid  in  vinegar). 

O 
CH2(NH2)COOH     ......     Amido  acetic  acid. 

COOH 

COOH,  or  (COOH)2    .....     Oxalic  acid. 
CH2COOH 

CH2COOH     ......     .     .     Succinic  acid. 

CH2COOH 

I 
CH(NH2)COOH      ......     Amido  succinic  acid  (the  aspartic  acid 

in  pumpkin  seed,  beets,  etc.). 
CH2CONH2 

CH(NH2)COOH      ......     Amido  succinamic  acid  (the  asparagin 

found  in  asparagus,  in  beans  and 
peas,  and  in  many  seeds  when  ger- 
H  minating). 


H—  CT         C—  H 

C6H6,  or          |  ||  ...     Benzene. 

H—  C.          C—  H 


H 
C6H5  —  OH      ........     Hydroxy  benzene,  or  phenol  (carbolic 

acid). 
C6H5  —  NH2     ........     Amido  benzene,  or  anilin. 

C6H3(OH)3      ........     Trihydroxy    benzene,     or     pyrogallol 

(pyrogallic  acid). 
C6H3(NH2)3     ........     Triamido  benzene. 

C10H14N2    .........     Dipyridyl  hexahydrid,  or  nicotin  (the 

alkaloid  of  tobacco). 
C17H21NO4       ........     Morphin  (the  alkaloid  of  opium,  from 

the  poppy). 
C2iH22N2O2     ........     Strychnin   (the  alkaloid  of  nux  vom- 

ica). 
Q^f^NesOreSs  .......     Albumen,  or  the  white  of  egg.     (For- 

mula suggested  by  Schutzenberger  ) 


PLANT   FOOD   AND   PLANT   GROWTH 


39 


Zein,  the  most  abundant  proteid  in  corn  (Zea  mays),  has  the 
following  composition: 

Carbon   ....  55.15  per  cent. 

Hydrogen   ...  7.24  per  cent. 

Oxygen.     .     .     .  20.77  per  cent. 

Nitrogen     .     .     .  16.22  per  cent. 

Sulfur     ....  .62  per  cent. 

According  to  this  analysis,  the  molecule  of  zein  might  be  repre- 
sented by  the  following  formula: 


Ordinary  corn  contains  n  per  cent  of  protein,  of  which  about 
one  half  consists  of  the  proteid  zein.  This  nitrogenous  substance 
has  been  separated,  purified,  and  investigated  with  very  great  care, 
especially  by  Chittenden  and  Osborne  (American  Chemical  Journal 
(1891),  jj,  453,  529;  (1892),  14,  20).  The  percentage  composition 
represents  the  average  of  several  closely  agreeing  analyses  of  what 
was  believed  to  be  very  pure  zein.  Based  on  the  percentage  of 
sulfur,  the  molecular  weight  cannot  be  less  than  about  5000,  and 
the  formula  given  above  or  some  multiple  of  it  must  be  approxi- 
mately correct. 

Certainly  the  proteid  molecule  is  exceedingly  complex,  and  the 
number  of  different  proteids  is  very  large.  They  all  contain 
nitrogen,  usually  about  16  per  cent,  and  some  of  them  contain 
also  sulfur  and  phosphorus. 

Sulfur.  This  is  an  essential  element  for  all  plants,  but  the  amount 
required  for  normal  growth  and  full  development  is  relatively  very 
small,  even  when  compared  with  the  small  percentage  present  in 
the  earth's  crust.'  Most  proteids  (as  zein,  for  example)  contain 
sulfur,  but  the  percentage  is  usually  very  low.  It  is  present, 
however,  in  organic  combination,  and  does  not  give  the  ordi- 
nary tests  for  sulfates,  the  form  in  which  it  is  usually  taken  from 
the  soil. 

Many  of  the  simpler  organic  compounds  of  sulfur  are  well  known, 
and  some  can  be  made  artificially.  The  oil  of  onions  and  garlic, 
which  gives  to  those  plants  their  peculiar  odor  and  taste,  consists 


40  SCIENCE  AND   SOIL 

chiefly  of  allyl  l  sulfid  (C3H6)2S;  and  mustard  oil  is  also  composed 
of  organic  sulfur  compounds. 

Phosphorus.  Phosphorus  is  the  Greek  word  for  the  morning 
star,  and  signifies  light.  The  element  phosphorus  is  closely  asso- 
ciated with  the  beginning  of  all  forms  of  mortal  life.  The  nucleus 
of  every  living  cell  in  plants  and  animals  is  rich  in  phosphorus. 
Nuclein,  the  phosphorized  nitrogenous  constituent  of  the  cell- 
nucleus,  contains  as  high  as  10  per  cent  of  the  element  phosphorus, 
although  it  may  contain  no  sulfur.  The  following  formula  has  been 
suggested  byMiescher  for  nuclein  derived  from  animal  cells: 


Lecithin,  C44H90O9NP,  is  a  well-known  organic  phosphorus  com- 
pound, which  it  is  thought  may  have  some  controlling  influence  in 
the  formation  of  fats  and  oils.  Ordinary  corn  contains  about  5 
per  cent  of  oil,  of  which  1.5  per  cent  consists  of  lecithin;  that  is, 
i^  pounds  of  lecithin  are  found  in  100  pounds  of  the  oil. 

It  should  be  remembered  that,  while  sulfur  is  contained  in  many 
proteids,  phosphorus  is  present  in  every  cell  of  every  plant.  The 
grain  or  seed  of  plants  contains,  as  a  rule,  more  than  fifty  times  as 
much  phosphorus  as  sulfur.  The  phosphorus  of  the  corn  kernel  is 
found  largely  in  the  germ.  In  1000  pounds  of  corn  there  are  about 
100  pounds  of  germs  containing  more  than  two  pounds  of  the  ele- 
ment phosphorus.  About  95  per  cent  of  the  ash  obtained  from  the 
burning  of  corn  consists  of  the  phosphates  of  potassium  and 
magnesium.  Hay,  straw,  and  other  coarse  products  usually 
contain  more  sulfur  than  the  grain,  but  these  coarser  parts  com- 
monly remain  on  the  farm,  while  the  grain  is  more  likely  to  be  sold. 

1  The  monovalent  allyl  group  (  —  CaHs)  differs  from  "the  trivalent  glyceryl 
(sCsHs)  only  in  having  a  double  bond,  as  shown  in  allyl  alcohol  and  glycerin 
(which  might  also  be  called  glyceryl  alcohol)  : 

Allyl  alcohol  Glycerin 

CH2  CH2OH 

II  I 

GH  CHOH 

I  I 

CH2OH  CH2OH 


PLANT   FOOD   AND   PLANT   GROWTH  41 

The  proteid  of  milk,  called  casein,  has  the  following  composition : 

Carbon  .  .  .  .  53.30  per  cent. 
Hydrogen  .  .  .  7.07  per  cent. 
Oxygen  ....  22.03  Per  cent. 
Nitrogen  .  .  .  15.91  per  cent. 

Sulfur 82  per  cent. 

Phosphorus     .     .        .87  per  cent. 

A  ton  of  wheat  bran  contains  about  24  pounds  of  phosphorus, 
or  1.22  per  cent.  About  86  per  cent  of  the  total  phosphorus  in 
bran  is  soluble  in  water,  and,  according  to  Patten  and  Hart  (New 
York  State  Agricultural  Experiment  Station  Bulletin  250),  this 
water-soluble  phosphorus  is  contained  in  the  salt  of  an  organic 
acid,  which  is  probably  identical  with  a  compound  investigated 
by  Posternak,  and  called  by  him  anhydro-oxymethylene  diphos- 
phoric  acid,  the  formula  being  C2H8P2O9.  As  determined  by  Patten 
and  Hart,  the  complex  salt  of  this  acid  which  constitutes  the  prin- 
cipal phosphorus  compound  in  wheat  bran,  has  the  following 
composition,  as  found  by  the  ultimate  analysis  of  the  isolated 
compound : 

Calcium 1.13  per  cent. 

Potassium 2.60  per  cent. 

Magnesium 5.80  per  cent. 

Carbon        I7-3Q  per  cent. 

Hydrogen 3.63  per  cent. 

Phosphorus 16.38  per  cent. 

Oxygen  (by  difference)      .     .     .  53.16  per  cent. 

The  free  acid  was  found  to  contain  10.63  Per  cent  °f  carbon, 
3.38  per  cent  of  hydrogen,  and  25.98  per  cent  of  phosphorus,  which 
corresponds  fairly  closely,  especially  in  phosphorus,  with  the 
theoretical  percentages,  which  any  one  can  compute  for  the  for- 
mula C2H8P2O9. 

The  mineral  part  of  animal  bone  consists  largely  of  tricalcium 
phosphate,  Ca3(PO4)2,  which,  when  pure,  contains  20  per  cent  of  the 
element  phosphorus,  as  can  be  easily  computed  by  any  one  who 
knows  the  atomic  weights.  In  100  pounds  of  raw  bone  are  about 


42  SCIENCE  AND    SOIL 

10  pounds  of  phosphorus.  The  phosphorus  required  by  animals 
is,  as  a  rule,  supplied  in  the  plants  that  serve  as  animal  foods. 

The  percentage  of  phosphorus  in  the  earth's  crust  is  small  when 
compared  with  the  requirements  of  plants,  especially  when  we  also 
consider  that  the  phosphorus  accumulates  in  the  more  concen- 
trated and  more  salable  products,  as  in  the  seed  or  grain,  and  also 
in  the  flesh,  bone,  and  milk,  of  animals. 

Phosphorus  is  usually  taken  up  by  plants  in  the  form  of  phos- 
phates, but  within  the  plant  it  enters  into  organic  combination 
as  shown  above. 

The  six  elements  thus  far  discussed  in  some  detail  —  carbon, 
oxygen,  hydrogen,  nitrogen,  phosphorus,  and  sulfur  —  are  all  non- 
metallic.  Three  of  them  —  oxygen,  hydrogen,  and  nitrogen — are 
gases  in  the  free  state,  and  the  other  three  —  carbon,  phosphorus, 
and  sulfur — are  nonmetallic  solids.  Four  other  elements  are  also 
absolutely  essential  to  the  growth  of  all  agricultural  plants. 

Potassium  and  magnesium.  These  are  metallic  elements  which 
have  very  important  functions  in  plant  growth  and  which  are  re- 
quired in  considerable  amounts.  Both  are  stored  in  the  seed  in 
relative  abundance,  and  are  found  in  the  ash  of  grains  in  the  form 
of  phosphates,  although  still  larger  amounts  of  potassium  are 
stored  in  the  coarser  parts  of  plants  (as  in  straw,  cornstalks,  etc.). 

It  is  not  known  that  potassium  and  magnesium  are  essential 
constituents  of  protoplasm,  but,  like  nitrogen  and  phosphorus, 
they  are  found  in  largest  proportions  in  the  embryo  tissues.  It  is 
suggested  that  one  of  their  essential  functions  may  be  as  carriers  of 
nitrogen  and  phosphorus  in  the  form  of  definite  salts  (as  nitrates 
and  phosphates)  capable  of  reaction  with  certain  products  result- 
ing from  the  fixation  of  carbon,  oxygen,  and  hydrogen.  Certainly 
it  is  not  sufficient  that  phosphorus,  for  example,  shall  merely  be 
carried  in  the  form  of  some  soluble  phosphate  into  the  laboratory 
(the  leaf)  of  the  plant,  but  the  compound  must  be  such  that  the 
metallic  base  will  release  the  phosphorus  at  the  proper  time,  in 
order  that  it  may  enter  the  organic  combination  and  thus  become 
a  part  of  the  living  organism. 

It  is  known  that  organic  acids  are  developed  by  the  plant  with 
which  potassium  and  other  bases  carried  into  the  plant  in  the  form 
of  nitrates,  phosphates,  etc.,  may  unite,  and  do  unite,  at  some  time 


PLANT  FOOD  AND  PLANT  GROWTH      43 

during  the  life  of  the  plant;  for  some  of  the  potassium  that  enters 
the  plant  roots  as  nitrates,  phosphate,  or  sulfate  is  afterward 
found  in  the  plant  in  organic  salts,  as  tartrate  (in  grapes) ,  oxalate 
(in  sorrel) ,  etc.  There  appears  to  be  little  or  no  evidence  that  any 
living  organic  compounds  of  potassium  or  magnesium  exist. 

It  is  the  common  belief  that  potassium  has  large  influence  over 
the  formation  of  carbohydrates;  but  the  information  is  not  suffi- 
cient to  determine  whether  this  influence  is  direct  or  very  indirect, 
as  in  maintaining  the  general  health  of  the  plant  by  having  some 
absolutely  necessary  part  in  reactions  involving  the  transference 
of  nitrogen  or  phosphorus  from  inorganic  compounds  to  the  living 
organic  combination. 

The  potassium  contained  in  plants  is  in  large  part  very  easily 
removed  by  leaching  with  water,  and  hence  peaty  swamp  soils 
consisting  largely  of  organic  matter  are  frequently  very  deficient 
in  potassium.  While  potassium  and  magnesium  are  required  by 
plants  in  very  considerable  amounts,  as  stated,  and  as  shown  in 
Table  2,  yet,  when  measured  by  the  average  composition  of  the 
earth's  crust  and  by  average  crop  requirements,  the  supply  of  these 
two  elements  is  very  great. 

Calcium  and  iron.  These  elements  are  absolutely  essential  to 
the  normal  growth  and  development  of  all  agricultural  plants, 
but  for  the  grain  crops  the  amounts  positively  necessary  are  so 
extremely  small  and  the  quantities  present  in  the  earth's  crust  are 
so  extremely  large  that  it  is  rarely  that  either  calcium  or  iron  is 
furnished  to  such  plants  in  amounts  insufficient  to  perform  their 
essential  functions,  except,  of  course,  when  they  are  artificially 
withheld,  as  in  investigational  work.  Legume  plants  are  a  very 
marked  exception,  however,  so  far  as  calcium  is  concerned. 

Iron  evidently  has  some  important  connection,  direct  or  indi- 
rect, with  the  formation  of  chlorophyll  (the  green  coloring  matter 
of  leaves) ;  for,  if  iron  is  withheld  from  the  plant,  the  leaves  do  not 
become  green,  and  if  later  iron  is  supplied,  the  chlorophyll  soon 
begins  to  develop.  On  the  other  hand,  analysis  has  shown  that  the 
chlorophyll  itself  does  not  contain  iron,  and  the  somewhat  common 
assumption  that  the  green  color  of  plants  is  due  to  the  presence  of 
iron  compounds  of  that  color  is  incorrect. 

The  iron  held  in  nuclein  compounds  is  not  dissolved  out  by  dilute 


44  SCIENCE  AND   SOIL 

hydrochloric  acid,  —  a  fact  which  indicates  that  the  iron  is  a  con- 
stituent of  the  living  matter  of  plants.  Animals  also  have  a  small 
but  absolute  requirement  for  iron. 

Aside  from  oxygen,  iron  is  the  most  abundant  essential  plant- 
food  element,  constituting  about  4^-  per  cent  of  the  solid  crust  of 
the  earth,  although  the  amount  required  by  plants  is  very  insig- 
nificant. Thus,  the  earth  contains  more  than  40  times  as  much 
iron  as  phosphorus,  while  the  corn  kernel  contains  nearly  40  times 
as  much  phosphorus  as  iron,  so  that  the  supply  of  phosphorus  would 
be  depleted  as  much  by  the  removal  of  100  crops  as  the  supply 
of  iron  would  be  by  160,000  crops. 

While  a  very  small  supply  of  calcium  is  of  vital  importance, 
considerable  amounts  of  that  element  are  commonly  taken  up  and 
deposited  in  the  coarser  parts  of  plants,  as  in  straw,  cornstalks, 
and  hay,  and  large  supplies  of  calcium  are  required  for  legumes, 
especially  for  clover  and  alfalfa.  This  larger  use  of  calcium  appears 
to  be  due,  especially  in  grain  crops,  to  its  power  as  a  base  to  unite 
with  organic  acids  that  might  otherwise  injure  the  plant;  and  the 
salts  formed  are  commonly  deposited,  not  in  the  seed  or  with  stored 
food  materials,  but  in  the  older  tissues  as  inert  matter. 

The  common  use  of  certain  calcium  compounds,  such  as  burned 
lime  and  ground  limestone,  for  correcting  soil  acidity  should  not 
be  confused  with  the  essential  need  of  the  element  calcium  as  plant 
food.  Even  strongly  acid  soils  often  contain  abundance  of  the  ele- 
ment calcium  for  plant  food,  not  in  the  form  of  carbonates,  but  in 
silicates,  which,  however,  have  no  power  to  correct  soil  acidity. 

Aluminum,  silicon,  sodium,  chlorin,  and  manganese.  These 
elements  are  not  known  to  be  essential  to  plant  growth,  but  they 
are  commonly  found  in  plants,  although  the  amount  of  manganese 
is  very  small  and  that  of  aluminum  still  smaller. 

The  opinion  that  silicon  was  essential  and  gave  stiffness  to  the 
straw  of  cereals  is  not  correct,  and  the  report  that  manganese 
exerts  a  marked  stimulating  action  on  plant  growth  has  not  been 
verified  upon  more  thorough  investigation.  Sodium  is  now  known 
to  be  a  nonessential,  but  there  is  still  a  possible  question  regarding 
chlorin.  According  to  Pfeffer,  "  it  remains  for  precise  researches 
to  determine  whether  a  minimal  amount  is  essential,  or  whether 
chlorin  simply  favors  growth  under  special  cultural  conditions." 


PLANT   FOOD   AND   PLANT   GROWTH  45 

Common  functions.  Some  common  functions  may  be  performed 
by  several  elements.  Thus,  if  there  is  need  for  a  base  to  correct  an 
excess  of  acid  that  has  developed  in  the  plant,  sodium  may  serve 
as  well  as  potassium,  although  with  enough  potassium  provided, 
no  sodium  is  needed.  As  already  stated,  the  largest  use  of  calcium 
appears  to  be  in  this  line,  in  which,  perhaps,  manganese,  magne- 
sium, or  iron  might  serve  equally  well  if  they  were  present  in  the 
plant  in  sufficient  amount.  Likewise,  in  solvent  compounds,  chlorin 
may  serve  as  well  as  nitrogen  or  phosphorus,  but  cannot  take  their 
place  in  living  tissue. 

We  shall  also  consider  in  the  following  pages  the  value  to  plants 
of  certain  materials  when  applied  to  certain  soils,  which  serve  not 
as  plant  food,  but  rather  as  soil  stimulants,  having  power  to  liberate 
from  the  soil  some  essential  plant-food  element  more  rapidly  than  it 
would  otherwise  become  available  —  an  action  that  may  result  in 
temporary  profit  and  ultimate  land  ruin.  Caustic  lime,  salt, 
gypsum  (land-plaster),  and,  under  certain  conditions,  commercial 
fertilizers,  and  even  farm  manure,  clover,  and  green  manures,  may 
act  in  part,  at  least,  as  soil  stimulants;  and,  to  guard  against  such 
injurious  action,  practice  must  be  controlled  by  science  (knowl- 
edge). 


CHAPTER  IV 

THE    EARTH'S    CRUST 

NEARLY  98  per  cent  of  the  solid  crust  of  the  earth  consists  of 
silicates  of  the  six  metals,  aluminum,  iron,  calcium,  potassium, 
sodium,  and  magnesium  (in  this  order  of  relative  abundance); 
and  the  remainder  is  largely  composed  of  the  closely  related  titan- 
ates. 

Silicon.  Silicon  in  the  mineral  matter  constituting  the  earth's 
crust  corresponds  to  carbon  in  the  organic  matter  of  the  vegetable 
and  animal  kingdoms.  In  all  of  the  great  groups  of  organic  com- 
pounds the  molecule  is  built  up  by  the  linking  power  of  the  four- 
handed  carbon  atom,  as,  for  example,  in  the  hydrocarbon,  hexane 
(C6H14): 

H     H     H     H     H     H 

I       I       I       I       I       I 
H— C— C— C— C— C— C— H 

I        I        I        I        I        I 
H     H      H     H     H     H 

Silicon  is  the  second  member  of  the  carbon  group  *  in  the  periodic 
system,  as  shown  on  page  u,  and  its  linking  power  is  also  very 
great,  although  alternating  with  oxygen  and  metals  and  restricted 
mainly  to  silicates.  Thus,  instead  of  the  almost  unlimited  number 
of  hydrocarbons,  carbohydrates,  and  other  numerous  compounds 
of  carbon,  hydrogen,  and  oxygen  (alcohols,  fats,  organic  acids,  etc.), 
there  are  but  four  such  silicon  compounds  known:  SiH4,  SiO2, 
OSi(OH)2  or  H2SiO3,  and  Si(OH)4  or  H4SiO4,  which  differs  from 
silicon  dioxid  by  two  molecules  of  water. 

1  A  most  interesting  compound  is  SiC,  silicon  carbid,  so-called  carborundum, 
formed  by  the  union  of  the  two  tetravalent  elements  and,  next  to  the  diamond,  one 
of  the  hardest  known  substances. 

46 


THE   EARTH'S    CRUST  47 

The  numerous  natural  polysilicates  (poly-  means  many)  compos- 
ing granite  and  most  other  rocks  of  the  earth's  crust  are  salts  of 
polysilicic  acids,  although  the  acids  themselves  are  not  known  to 
exist  free  from  the  basic  elements  or  radicles.  The  following  may 
illustrate  a  few  of  the  possible  combinations,  the  last  three  being 
known  only  in  salts  in  which  bases  appear  in  place  of  the  acid 
hydrogen  : 

Silicon  dioxid,  SiO2  .     .  .  .    O  =  Si=O. 

Metasilicic  acid,  H2SiO3  .  .    O  =  Si  =  (OH)2. 

Orthosilicic  acid,  H4SiO4  .  .     (HO)2  =  Si=(OH)2. 

Disilicic  acid,  H2Si2O6  .  .  .     HO-Si=O3=Si-OH. 

Polysilicic  acid,  H4Si3O8  .  (HO)2=Si=O2=Si=O2=Si=(OH)2. 

J  (HO).'  Si-°s  =  Si  -°.  -  Si  -°«  =  Si  -  <OH>r 

Among  the  most  common  mineral  compounds  found  in  granite 
is  ordinary  felspar,  or  orthoclase,  or  potassium  aluminum  poly- 
silicate,  KAlSi3O8,  or  (KAlSi3O8)2,  whose  structural  formula  may 
be  represented  thus: 

/ox   /o        o        o 

KX       >Si<       >Si<       >Si< 

<y   xox  xox  x 
/X      o        o        o 

A1     si      si      si 


This  is  sufficient  to  illustrate  what  is  meant  by  polysilicates. 
Other  silicates  differ  from  the  common  felspar  by  the  substitution 
of  other  elements  for  potassium  or  aluminum  or  both,  and  also 
by  different  proportions  of  the  various  constituents,  as: 

Orthoclase  (potassium  felspar)       ....  KAlSi3O8. 

Albite  (sodium  felspar)    .......  NaAlSi3O8. 

Anorthite  (calcium  felspar)  ......  CaAl2Si2O8. 

Crysolite  (magnesium  iron  silicate)    .     .     .  MgFeSiO4. 

In  some  cases  hydroxyl  groups  are  included,  and  when  such  com- 
pounds are  heated,  two  hydroxyl  groups  are  broken,  leaving  one 
oxygen  atom  in  their  place,  thus  yielding  water  and  anhydrous 


48 


SCIENCE   AND   SOIL 


silicate.    Silicates  from  which  water  can  be  separated  are  called 
hydrated  silicates  or,  sometimes,  acid  silicates: 

Steatite  (soapstone) Mg6Si4O13(OH)2. 

Kaolin  (clay) AlgSijOgCOH)*. 

Commonly,  the  silicates  of  the  earth's  crust  are  more  or  less 
mixed,  so  that  samples  of  pure  compounds  are  rarely,  if  ever, 
found  in  native  state.  Following  are  the  results  of  analysis  of 
specimens  of  orthoclase,  kaolin,  and  steatite  as  found  in  nature: 

TABLE  3.   PERCENTAGE  COMPOSITION  OF  SILICATES 


CONSTITUENTS 

ORTHOCLASE 
(POTASSIUM 
FELSPAR) 

KAOLIN  (CLAY) 

STEATITE 
(SOAPSTONE) 

Potassium  

11.64 
.04 
.24 

trace 

30.89 
9.84 
•93 

•34 
.07 
.11 

•55 

22.87 
19-59 
•°3 
12.83 
43.61 

.27 

15-43 
2.32 

9-15 

19.91 
3.22 
.12 
8-45 
4I-I3 

Magnesium      

Calcium      

Iron  

Silicon    

Aluminum 
Sodium  

\Vater  of  hydration 

Oxygen,  etc  

46.42 

While  the  samples  of  orthoclase  and  kaolin  were  fairly  pure,  the 
steatite  contained  other  metals  aggregating  almost  as  much  as 
the  magnesium. 

Granite  and  gneiss.  These  are  among  the  most  common  rocks, 
the  former  being  of  igneous  or  eruptive  origin,  while  gneiss  is 
essentially  the  same  material  in  sedimentary  stratified  form. 
In  other  words,  when  granite  has  been  disintegrated  by  the  action 
of  heat  and  cold,  rain  and  frost,  has  been  transported  by  wind  and 
flowing  water,  has  been  redeposited  in  strata  over  river  bottoms,  or 
ocean  beds,  and  has  become  reformed  into  compact  masses  by  the 
cementing  action  of  acids,  alkalies,  or  salts,  it  is  then  called  gneiss. 
Gneiss  is  one  of  the  oldest  stratified  rocks,  and  was  formed  chiefly 
previous  to  the  beginning  of  plant  or  animal  life  on  the  earth. 

Granite  and  gneiss  consist  principally  of  the  four  mineral  groups, 
felspar,  hornblende,  mica,  and  quartz.  Of  these  the  felspar  group 


THE   EARTH'S    CRUST 


49 


has  already  been  discussed.  The  hornblendes  (or  amphiboles)  in- 
clude certain  white  or  light-colored  silicates  of  calcium  and  mag- 
nesium, often  with  fibrous  structure,  of  which  common  asbestos  is  a 
good  example;  also  silicates  of  aluminum,  magnesium,  and  iron, 
of  darker  colors,  green  or  black.  The  micas  include  light-colored 
or  transparent  potassium  aluminum  silicates  and  black  silicates  of 
aluminum,  magnesium,  and  iron.  While  the  hornblendes  are  often 
fibrous,  the  micas,  as  a  rule,  are  easily  split  into  the  well-known  mica 
sheets. 

Quartz.  Quartz,  when  pure,  is  crystallized  silicon  dioxid  (SiO2), 
but  it  is  often  colored  by  small  amounts  of  metallic  compounds. 
Aside  from  being  a  common  constituent  of  granite  and  gneiss  and 
of  many  other  less  abundant  silicate  rocks,  quartz  is  often  found  in 
rock  masses  or  seams  in  a  nearly  pure  state.  Quartz  sand  is  not 
uncommon,  but  the  opinion  that  sand  and  quartz  are  synonymous 
terms  is  very  incorrect,  for  sand  usually  includes  very  considerable 
amounts  of  granite  or  gneiss  and  other  mineral  particles. 

The  following  statement  shows  the  composition  of  common 
samples  of  original  granite,  fresh  gneiss,  and  decomposed  gneiss; 
also  the  percentage  of  each  constituent  saved  from  the  fresh  gneiss 
and  found  in  the  decomposed  gneiss,  as  computed  by  Merrill,1 
assuming  no  loss  of  aluminum,  which  indicates  a  total  loss  of  44.67 
per  cent  of  the  original  rock.  They  serve  only  as  illustrations,  and 
other  samples  may  vary  greatly  from  these. 

TABLE  4.   PERCENTAGE  COMPOSITION  OF  ROCK 


CONSTITUENTS 

FRESH 
GRANITE 

FRESH 
GNEISS 

DECOMPOSED 
GNEISS 

PERCENTAGE 
SAVED 

Phosphorus       

.04 

3-3° 
.29 
1.32 
3-34 

32-77 
7.64 
2.90 
.89 
47.60 

.11 

3-54 
.64 
3-i7 
6-34 

28.49 
8.94 
2.09 
.62 
46.06 

.21 

.92 
.24 

trace 
8.52 

21.27 
14.05 
.16 

13-75 
40.88 

IOO.OO 
16.48 

25-3° 
o.oo 

'  85.65 

47-55 

IOO.OO 

4-97 

Potassium    

Magnesium       

Calcium  

Iron    

Silicon     

Aluminum    

Sodium    

Water  of  hydration    .     .     . 
Oxygen   etc 

1  "  Rocks,  Rock  Weathering,  and  Soils,"  1897,  p.  215. 


50  SCIENCE  AND   SOIL 

Gneiss  may  contain  constituents  not  always  present  in  granite, 
because  of  admixture  of  other  materials  in  transportation;  also 
certain  constituents  are  likely  to  be  lost  to  some  extent  in  the  origi- 
nal disintegration  and  transportation,  and  to  a  great  extent  in  the 
subsequent  more  complete  decomposition,  so  that  often  certain 
constituents  may  show  higher  percentages  in  the  final  residue. 

Zeolites.  Zeolites  are  formed  from  partially  decomposed  min- 
erals, like  granite  and  gneiss.  They  are  hydrated  double  silicates 
of  aluminum  with  calcium  or  sodium,  and  may  contain  other  bases, 
especially  potassium.  They  are  credited  with  important  functions 
in  soils  to  which  further  reference  will  be  made. 

Shale,  kaolin,  and  clay.  These  materials  consist  chiefly  of  hydrated 
aluminum  silicate  related  to  the  mineral  kaolinite,  Al2Si2O5(OH)4, 
and  representing  in  part  the  final  residue  from  the  decom- 
position of  felspar,  hornblendes,  micas,  etc.,  from  granite,  gneiss, 
and  other  silicate  rocks.  They  may  be  grouped  under  the  general 
term  argillites  (from  argil,  meaning  potter's  clay) .  Slate  is  the  well- 
known  roofing  material.  Shale  is  the  term  applied  to  the  more 
thinly  stratified  formations  which  disintegrate  more  or  less 
readily  when  exposed  to  the  weather.  Kaolin  is  common  fire  clay. 
Ordinary  brick  clay  belongs  in  the  same  group,  and,  in  fact,  shale 
itself  is  often  ground  and  used  for  making  brick  or  tile. 

Aluminum  silicate  is  the  final  residue  from  the  disintegration  of 
many  different  rocks,  and  consequently  is  itself  one  of  the  most 
permanent  substances.  The  oldest  records  of  man  have  been  pre- 
served in  burnt  clay,  both  in  tablets  and  in  pottery. 

Carbonates.  The  carbonates  include  a  very  important  group  of 
rocks,  although  they  constitute  a  small  portion  of  the  earth's 
crust  when  compared  with  the  silicates.  Of  the  carbonates,  the 
common  limestone,  calcium  carbonate,  CaCO3,  is  by  far  the  most 
abundant.  It  is  frequently  quite  impure.  Marble  is  calcium  car- 
bonate, mottled  or  colored  with  impurities  and  of  sufficiently  close 
texture  to  admit  of  polishing.  The  mineral  calcite  is  very  pure 
crystallized  calcium  carbonate,  CaCO3.  Magnesian  limestone  (dolo- 
mite) is  a  double  carbonate  of  calcium  and  magnesium,  CaMg(CO3)2, 
but  this  compound  is  frequently  mixed  with  calcium  carbonate, 
CaCO3,  so  that  varying  percentages  of  calcium  and  magnesium 
are  found  in  dolomitic  limestone. 


THE   EARTH'S   CRUST 


Most  limestone  deposits  are  marine  formations,  and  frequently 
consist  largely  of  shells,  but  this  is  not  always  the  case.  Small 
amounts  of  calcium  carbonate  are  found  in  many  other  stratified 
rocks. 

Impure  limestones  containing  silicate  minerals  may  lose,  by 
weathering  and  leaching,  practically  all  of  the  calcium  carbonate 
or  magnesium  carbonate  which  they  originally  contained  and  leave 
a  residue  free  from  carbonates,  as  shown  by  the  following  analyses: 

TABLE  5.   COMPOSITION  OF   FRESH  LIMESTONE  AND  ITS  RESIDUAL  CLAY 


CONSTITUENTS 

FRESH 

LntESTOXE 

RESIDUAL 
CLAY 

PERCENTAGE 
SAVED  OF  EACH 
CONSTITUENT 

Phosphorus      

.29 
.18 

3J-99 
1.64 

i-94 

2.22 
.12 

9-3° 

2.26 

45-37 

1.11% 
.80 
.16 
2.79 
1.  29 

15.82 

ii.  61 
none 
10.76 
39.08 

I0.24% 

10.62 
1.07 
10.44 

IOO.OO 

88.65 
46.74 
42.41 

none 

Potassium  

Magnesium      

Calcium      

Iron  

Silicon    

Aluminum  

Sodium  

Manganese      

Carbonate  carbon     

\Vater  of  hvdration 

Oxygen  etc 

Penrose  *  presents  convincing  evidence  that  this  peculiar  man- 
ganese clay  was  derived  from  impure  limestone,  and  Merrill  ("Rocks, 
Rock  Weathering,  and  Soils,"  1897,  pp.  232,  233)  computes  that 
more  than  93.6  per  cent  of  the  original  rock  was  lost  during  the 
processes  of  decomposition,  weathering,  and  leaching,  assuming  no 
loss  of  silicon.  While  these  analyses  represent  very  satisfactorily 
the  general  results  of  rock  weathering,  it  must  not  be  assumed 
that  the  representation  is  exact  in  all  details.  In  minor  constitu- 
ents the  sample  of  rock  taken  for  analysis  may  vary  greatly  from 
the  particular  rock  stratum  of  which  the  sample  of  clay  was  the 
residue,  and  the  loss  by  leaching  of  the  same  constituent  may  also 
vary  greatly  in  different  rocks.  Thus,  in  the  decomposition  of  the 

1  Arkansas  Geological  Survey,  Annual  Report  for  1890,  p.  179. 


52  SCIENCE  AND   SOIL 

more  common  rocks  (see  Table  4)  the  loss  of  potassium  and  sodium 
is  very  great,  while  most  of  the  iron  and  phosphorus  is  likely  to  be 
found  in  the  residue. 

Sulfates.  Natural  sulfates  are  confined  chiefly  to  hydrated  cal- 
cium sulfate,  CaSO4(H2O)2  or  CaO2S(OH)4,  containing  about  18.6 
per  cent  of  sulfur  and  more  than  20  per  cent  of  water  of  hydration. 
This  is  the  mineral  called  gypsum.  It  occurs  in  numerous  deposits, 
at  various  depths,  and  sometimes  extends  over  hundreds  of  square 
miles,  as  in  northern  Ohio.  Under  the  name  of  land-plaster  this 
mineral  has  been  used  very  extensively  in  places  as  a  soil  stimu- 
lant. Traces  of  calcium  sulfate  are  found  in  most  limestones  and 
in  some  other  rocks. 

Sulfids.  The  sulfids  of  iron  are  widely  distributed  in  nature. 
Iron  disulfid,  FeS2,  is  commonly  known  as  pyrite,  also  called 
"  fool's  gold,"  because  of  its  glitter  and  yellow  color.  One  form  of 
iron  disulfid  decomposes  quite  readily  when  exposed  to  air  and 
moisture,  and  yields  ferrous  sulfate,  FeSO4,  as  one  of  the  products. 

Phosphates.  These  occur  in  small  amount  in  connection  with 
many  other  rocks  and  minerals,  principally  in  the  form  of  calcium 
phosphate,  Ca3(PO4)2,  specifically  called  tricalcium  phosphate, 
when  mentioned  in  connection  with  the  artificial  dicalcium  phos- 
phate, Ca2H2(PO4)2,  or  monocalcium  phosphate,  CaH4(PO4)2. 

Granite  commonly  contains  a  trace  of  phosphorus,  and  in  gneiss 
about .  i  per  cent  of  phosphorus  is  found  as  an  average,  correspond- 
ing to  10  pounds  of  calcium  phosphate  (2  pounds  of  phosphorus) 
in  one  ton  of  gneiss.  Limestones  also  contain  calcium  phosphate, 
as  a  rule.  While  the  amount  is  usually  less  than  i  per  cent,  some 
quite  extensive  deposits  of  phosphatic  limestone  exist  which  con- 
tain from  10  to  30  per  cent  of  tricalcium  phosphate.  In  places 
where  such  rocks  have  been  long  exposed  near  the  surface,  the  cal- 
cium carbonate  has  been  largely  removed  by  leaching,  so  that  the 
remaining  porous  rock  may  contain  as  high  as  75  per  cent  of  the 
phosphates  of  calcium,  iron,  and  aluminum,  in  which  the  calcium 
compound,  Ca3(PO4)2,  greatly  predominates  (as  in  the  Tennessee 
brown  rock  phosphate). 

There  are  also  some  natural  deposits  of  compact  calcium  phos- 
phate rock,  varying  in  purity  from  about  40  to  80  per  cent  (as  the 
Tennessee  blue  rock  phosphate).  These  deposits  of  phosphate 


THE   EARTH'S   CRUST  53 

and  of  phosphatic  limestone  show  evidence  of  living  organisms 
having  been  connected  with  their  origin,  as  in  limestone  shells 
and  bony  skeletons. 

Apatite  is  crystallized  calcium  phosphate,  containing  small 
amounts  of  calcium  chlorid  or  calcium  fluorid.  This  mineral  is 
largely  found  in  masses,  but  traces  of  it  are  found  in  nearly  all 
other  rocks,  whether  of  igneous  or  aqueous  formation. 

Oxids.  Oxids  of  silicon,  iron,  and  aluminum  are  more  or  less 
abundant  and  distributed  almost  universally,  in  quartz  (SiO2)  and 
quartz  sand,  in  the  iron  ore,  hematite  (FegOg) ,  and  in  the  aluminum 
ore,  bauxite  (A12O3)  and  (Fe2O3). 

Other  deposits.  Various  other  deposits  found  naturally  in  the 
earth,  but  constituting  extremely  small  percentages  of  the  earth's 
crust,  include  common  rock  salt  (NaCl) ;  potassium  salts,  as  carnal- 
lite  (KClMgCl2  6  H2O) ;  and  kainit  (KaSO4MgSO4MgCl2  6  H2O), 
from  which  potassium  chlorid  (KC1)  and  potassium  sulfate  (K2SO4) , 
respectively,  are  separated;  saltpeter  (KNO3),  and  Chile  saltpeter 
or  sodium  nitrate  (NaNO3) ;  also  the  extensive  deposits  of  anthra- 
cite and  bituminous  coal,  the  former  consisting  of  nearly  pure 
carbon,  while  the  latter  contains  considerable  amounts  of  hydro- 
carbon compounds  in  addition  to  the  free  carbon. 


CHAPTER  V 

SOIL   FORMATIONS    AND    CLASSIFICATIONS 

Residual  soils.  Residual  soils  are  those  that  are  formed  in  place 
from  the  disintegration  of  rocks.  They  consist  of  the  least  soluble 
decomposition  products,  which  often  constitute  but  a  small  pro- 
portion of  the  original  rock.  Thus  a  limestone  containing  80  per 
cent  of  calcium  carbonate  and  20  per  cent  of  impurities  (as  poly- 
silicates,  etc.)  may  weather  to  a  soil  composed  entirely  of  the  im- 
purities from  which  the  calcium  carbonate  has  been  completely 
removed  by  leaching,  and  the  polysilicates  may  have  partially 
broken  down  into  acid  silicates,  zeolites,  clay,  oxids  of  silicon  and 
iron,  etc. 

Transported  soils.  These  are  also  formed  from  disintegrated  and 
partially  decomposed  rock,  but  instead  of  remaining  in  the  place 
previously  occupied  by  the  rock,  they  have  been  transported,  and 
often  retransported,  by  various  agencies  (materials  from  many 
sources  sometimes  being  mixed  together),  and  finally  deposited  in 
the  places  which  they  now  occupy.  Wind,  water,  and  glaciers 
are  the  chief  carrying  agencies. 

Glacial  material  (bowlder  clay)  is  characterized  by  the  presence 
of  worn  or  rounded  stones,  varying  in  size  from  sand  grains  to 
bowlders,  embedded  in  silty  clay.  While  glacial  drift  covers  exten- 
sive areas  in  northern  United  States,  sometimes  to  a  depth  of  100 
feet  or  more,  the  glacial  material  is  covered  in  many  areas  by  a 
deposit  of  loess,1  varying  in  depth  from  a  few  inches  to  several 
feet. 

Loess  is  characterized  in  part  by  the  absence  of  pebbles.  It 
consists  largely  of  silt,  with  some  very  fine  sand  and  but  little  clay. 
It  has  been  transported  by  wind,  as  a  rule,  and  in  places  is  found  in 
high  elevations  and  even  overlying  residual  soils,  but  in  deep  loess 
deposits,  as  in  the  bluffs  along  the  Mississippi  and  other  large 
streams,  evidences  are  found  of  some  transportation  by  water. 

1  This  word  is  taken  directly  from  the  German  (like  sauerkraut)  and  pronounced 
like/ess,  with  the  lips  protruded  as  in  whistling.  Similarly,  the  English  word  beef- 
steak has  been  adopted  into  the  German  language. 

54 


SOIL   FORMATIONS   AND    CLASSIFICATIONS 


55 


Alluvial  soils  are  the  common  formation  in  river  valleys  and  other 
lowlands  that  receive  deposits  of  material  washed  from  the  higher 
lands. 

Soil  materials.  Soil  materials  consist  of  stones,  gravel,  sand, 
silt,  clay,  and  organic  matter.  The  term  day,  as  correctly  used, 
is  applied  to  the  material  that  gives  to  certain  soils  their  sticky, 
plastic  property,  including  hydrated  aluminum  silicate  and  other 
plastic  substances,  in  part  reduced  probably  to  the  molecular 
state  of  division  and  without  granular  character,  although  most 
so-called  "  clay  "  contains  more  or  less  undecomposed,  or  but 
partially  decomposed,  mineral  particles.  Silt  includes  a  grade 
of  particles  that  are  smaller  than  sand,  impalpable  in  fact,  but 
still  granular  as  seen  through  the  microscope,  and  not  plastic 
when  free  from  clay. 

Soil  types.  Soil  types  are  based  largely  upon  the  relative  propor- 
tion of  these  several  soil  materials,  as  may  be  noted  by  inspection 
or  determined  by  mechanical  analysis.  The  following  general 
groups  are  recognized: 

TABLE  6.   SOILS:  GENERAL  GROUPS 


NUMBER 
LIMITS 

GROUP  NAMES 

DESCRIPTION 

o  to    9 

10  tO  12 

13  to  14 

Peat  soil 
Peaty  loam 
Muck     .     .     . 

With  25  to  75  per  cent  or  more  of  organic  matter. 
10  to  25  per  cent  of  organic  matter  with  loam. 
10  to  25  per  cent  of  organic  matter  with  much  clay. 

15  to  19 
20  to  24 

Clay       .     .     . 
Clay  loam  .     . 

Plastic  clay  predominating. 
Much  clay  with  loam. 

25  to  49 
5°  to  59 

Silt  loam    .     . 
Loam    .     .     . 

Much  silt  with  loam. 
Sand,  silt,  clay,  and  organic  matter  with  neither 
markedly  predominating. 

60  to  79 
80  to  89 

Sandy  loam     . 
Sand      .     .     . 

Much  sand  with  loam. 
Sand  without  much  silt  or  clay. 

90  to  94 
95  to  97 

_Q 

Gravelly  loam 
Gravel  .     .     . 

Stony  loam 
Rock  outcrop 

.Gravel  with  loam. 
Gravel  without  much  silt  or  clay. 

Stones  with  loam. 
Disintegrating  rock. 

9» 

99 

SCIENCE  AND   SOIL 


TABLE  7.   SOME  RECOGNIZED  SOIL  TYPES 


No. 


NAME 


No. 


NAME 


1  Deep  peat. 

2  Medium  peat  on  clay. 

2.  i  Medium  peat  on  clayey  sand. 

2.2  Medium  peat  on  sand. 

2.3  Medium  peat  on  rock. 

3  Shallow  peat  on  clay. 

3.  i  Shallow  peat  on  clayey  sand. 

3.2  Shallow  peat  on  sand. 

3.3  Shallow  peat  on  rock. 
10  Peaty  loam  on  clay. 

10.  i  Peaty  loam  on  clayey  sand. 

10.2  Peaty  loam  on  sand. 

10.3  Peaty  loam  on  rock. 
13  Muck  on  clay. 

13.1  Muck  on  clayey  sand. 

13.2  Muck  on  sand. 

13.3  Muck  on  rock. 

15  Drab  clay. 

15.1  Sandy  drab  clay. 

15.2  Gravelly  drab  clay. 

1 6  Gray  clay. 

20  Black  clay  loam. 

20.  i  Sandy  black  clay  loam. 
20. 2  Gravelly  black  clay  loam. 

21  Drab  clay  loam. 

21.  i  Drab  clay  loam  on  sand. 

22  Gray  clay  loam. 

25  Black  silt  loam. 

25.  i  Black  silt  loam  on  clay. 

26  Brown  silt  loam. 

26.1  Brown  silt  loam  on  clay. 

26.2  Brown  silt  loam  on  sand. 

26.3  Brown  silt  loam  on  till. 

26.4  Brown  silt  loam  on  gravel. 

26.5  Brown  silt  loam  on  rock. 

27  B  rown  silt  loam  over  gravel . 

28  Brown -gray    silt    loam    on 

tight  clay. 

29  Drab  silt  loam. 

29.1  Drab  silt  loam  on  clay. 

30  Gray  silt  loam  on  tight  clay. 

31  Deep  gray  silt  loam. 


32 

32.1 
33 

34 
34-i 

35 

35-i 

35-2 

35-3 

35-4 

35-5 

5° 

50.1 


51-2 


Si-5 

52 

53 

54 

60 

60.  i 

60.2 

60.4 

60.5 

61 

62 

63 
64 

65 
80 
81 
82 
90 

95 
98 

99 


Light  gray  silt  loam  on  tight 

clay. 

White  silt  loam  on  tight  clay. 
Gray-red  silt  loam  on  tight 

clay. 

Yellow-gray  silt  loam. 
Yellow-gray    silt    loam    on 

tight  clay. 
Yellow  silt  loam. 
Yellow  silt  loam  on  tight  clay. 
Yellow  silt  loam  on  clay. 
Yellow  silt  loam  on  sand. 
Yellow  silt  loam  on  gravel. 
Yellow  silt  loam  on  rock. 
Black  loam. 
Black  loam  on  clay. 
Brown  loam. 
Brown  loam  on  clay. 
Brown  loam  on  silt. 
Brown  loam  on  sand. 
Brown  loam  on  gravel. 
Brown  loam  on  rock. 
Gray  loam. 
Yellow  loam. 
Mixed  loam. 
Brown  sandy  loam. 
Brown  sandy  loam  on  silt. 
Brown  sandy  loam  on  sand. 
Brown  sandy  loam  on  gravel. 
Brown  sandy  loam  on  rock. 
Mixed  sandy  loam. 
Brown  fine  sandy  loam. 
Light  brown  fine  sandy  loam. 
Yellow  fine  sandy  loam. 
Gray  fine  sandy  loam. 
River  sand. 
Dune  sand. 
Beach  sand. 
Gravelly  loam. 
Gravel. 
Stony  loam. 
Rock  outcrop. 


SOIL   FORMATIONS   AND    CLASSIFICATIONS         57 

The  soil  strata  are  commonly  classed  as  top  soil  and  subsoil,  and 
in  the  name  of  a  soil  type  the  character  of  the  top  soil  is  indicated, 
and  also  that  of  the  subsoil  if  it  is  peculiar  or  markedly  different 
from  the  top  soil.  In  the  detail  soil  survey  of  Illinois  conducted 
by  the  State  Experiment  Station,  which  now  covers  about  thirty 
counties,  or  one  third  of  the  state,  the  preceding  soil  types  have 
been  recognized  and  mapped,  and  records  are  kept  under  the 
numbers  and  names  given. 

The  system  of  numbering  (similar  to  the  Dewey  library  system) 
is  flexible,  and  permits  additions  of  main  types  or  related  types 
(by  decimals) ,  and  the  name  is  designed  to  carry  with  it  a  definite 
suggestion  of  the  character  of  the  soil. 

NOTE  TO  CHAPTER  VI.  —  In  considering  the  subject  of  sulfur,  as  discussed 
in  the  following  pages,  the  reader's  attention  is  called  to  the  fact  that  recent 
investigations  show  soils  and  plants  to  contain  considerably  more  sulfur  than 
was  indicated  by  most  of  the  analyses  formerly  reported,  part  of  the  sulfur  hav- 
ing been  lost  in  the  older  methods  of  analysis  (as  suggested  on  page  64).  On 
the  other  hand,  where  this  larger  amount  of  sulfur  is  found  in  plants,  it  is  not 
known  to  be  required,  but  more  probably  is  merely  tolerated  by  the  plant.  It 
is  safe  to  conclude  that  a  plant  requires  all  the  sulfur  it  contains  only  when  it 
is  grown  on  a  soil  in  which  sulfur  is  the  element  which  limits  the  growth,  so  that 
the  addition  of  more  sulfur  would  increase  the  yield. 

In  the  author's  opinion,  the  fact  that  sodium  nitrate  is  usually  more  valuable 
than  ammonium  sulfate,  and  that  bone  meal  in  continued  use  gives  as  good  or 
better  results  than  acid  phosphate  (containing  calcium  sulfate),  justifies  the  con- 
clusion that  sulfur  deserves  no  more  consideration  than  is  hereinafter  given  to 
it.  (Note  the  results  from  plots  A  i  and  N  i  in  Table  66,  plots  5  and  6  in  Table 
68,  plots  5  and  17  in  Table  70,  and  plots  N  i  and  A  i,  N  3  and  A  3,  and  N  8  and 
A  8,  in  Table  718.  Also  compare  plots  6,  9,  10,  17,  and  19  with  plots  12  and 
35,  in  Table  80.) 

It  may  be  stated  that,  in  addition  to  the  sulfur  contained  in  the  soil  and  in 
addition  to  the  known  amount  brought  to  the  soil  in  rain,  there  is  an  unknown 
amount  absorbed  by  the  soil  directly  from  the  atmosphere,  owing  to  the  pres- 
ence of  sulfur  oxids  and  sulfur  acids  in  the  air  (as  products  of  the  combustion 
of  wood,  grass,  coal,  etc.)  and  to  the  movement  of  the  air  into  and  out  of  the 
pores  of  the  soil  with  the  changes  in  barometric  pressure  and  wind  velocity. 


CHAPTER  VI 

SOIL    COMPOSITION 

SOILS  IN  GENERAL 

ASIDE  from  the  organic  matter,  any  soil  material  (excepting 
quartz  sand,  but  including  granitic  sand)  will  commonly  contain 
all  of  the  elements  found  in  ordinary  silicate  rocks,  but,  of  course, 
in  very  varying  proportions.  Soils  contain  large  amounts  of  silicon 
and  much  aluminum  and  sodium,  none  of  which  are  essential  to 
plant  growth,  also  very  large  amounts  of  oxygen,  an  element  which 
as  plant  food  is  supplied  in  the  carbon  dioxid  taken  into  the  plant 
through  the  leaves.  This  means  that  about  85  per  cent  of  the  solid 
crust  of  the  earth  has  no  value  as  plant  food.  This  includes  not 
only  silicon  dioxid  (as  quartz  sand),  aluminum  silicate  (as  pure 
clay),  and  aluminum  sodium  polysilicates,  but  also  these  elements 
when  present  in  other  combinations. 

The  remaining  abundant  elements,  iron,  calcium,  magnesium, 
and  potassium,  are  all  essential  as  plant  food.  Of  these  four,  iron  is 
the  most  abundant  in  the  earth  and  the  least  abundant  in  plants, 
and,  so  far  as  the  writer  is  aware,  soil  has  never  been  known  to  be- 
come deficient  in  iron  as  measured  by  crop  requirements. 

Calcium  and  magnesium  are  somewhat  less  abundant  than  iron, 
and  are  required  by  crops  in  very  much  larger  amounts,  and  on 
some  soils  crop  yields  are  appreciably  increased  by  the  application 
of  one  or  both  of  those  elements  in  suitable  compounds,  but  in 
many  or  most  such  cases  the  increase  in  crop  yields  is  not  due  to 
the  direct  effect  of  the  calcium  or  magnesium  as  plant  food,  but 
rather  to  the  indirect  effect  their  compounds  may  produce  in 
increasing  the  availability  of  other  less  abundant  plant-food 
elements. 

In  the  average  crust  of  the  earth,  potassium  is  slightly  more 
abundant  than  magnesium  but  less  abundant  than  iron  or  calcium. 
Of  these  four  elements,  potassium  is  required  by  plants  in  greatest 


SOIL   COMPOSITION 


59 


amount,  but  nevertheless  the  total  supply  of  potassium  in  nearly  all 
soils  is  exceedingly  large  compared  with  crop  requirements;  and, 
while  it  has  a  money  value  in  commercial  fertilizers  and  is  quite 
extensively  used,  there  is  much  evidence  to  show  that  on  many 
soils  the  influence  which  it  produces  is  due  in  part  at  least  to  in- 
direct effects,  as  in  the  liberation  of  other  more  deficient  plant- 
food  elements. 

Sulfur  and  phosphorus  are  not  in  the  same  class  with  the  eight 
abundant  elements  composing  the  silicates;  and  between  these  two 
elements  there  are  also  marked  differences,  since  sulfur  is  brought 
to  the  earth  in  rain  in  considerable  amounts  and  is  also  about  as 
abundant  as  phosphorus  in  the  earth's  crust,  while  crops  require 
from  three  to  ten  times  as  much  phosphorus  as  sulfur. 

If  we  disregard  the  three  elements  which  agricultural  plants  ob- 
tain from  the  air  and  water  (in  CO2  and  H2O),  as  being  in  large 
measure  beyond  our  control,  we  may  secure  a  clear  conception  of 
the  relative  abundance  of  the  remaining  essential  plant-food  ele- 
ments, based  both  upon  the  most  original  natural  supplies  and  upon 
crop  requirements,  by  a  study  of  Table  8. 

TABLE  8..  RELATIVE  "SUPPLY  AND  DEMAND"  OF  SEVEN  ELEMENTS 


.ESSENTIAL  PLANT-FOOD  ELEMENTS 

POUNDS  IN  2  MIL- 
LION OF  THE 
AVERAGE  CRUST 
OF  THE  EARTH 

POUNDS  IN 
100  BUSHELS 
OF  CORN 
(Grain  only) 

NUMBER  OF 
YEARS'  SUPPLY 
INDICATED 
(See  Table  2) 

Phosphorus     

22OO 

17 

I3O 

Potassium  

4Q2OO 

10 

2600 

Magnesium      

48000 

7 

7OOO 

Calcium   '  

68800 

if 

"XOOO 

Iron  

88600 

I 

2OOOOO 

Sulfur     

22OO 

i 

1  0000 

Nitrogen  in  air     

70  million  Ib. 

IOO 

7OOOOO 

over  one  acre 

Two  million  pounds  correspond  to  the  weight  of  the  plowed  soil 
of  an  acre  of  average  land  to  a  depth  of  6|  inches  (counting  300,000 
pounds  per  acre  inch) ,  so  that  the  supply  of  the  plant-food  elements 
given  in  Table  8  is  simply  what  would  be  contained  in  an  acre  of 


60  SCIENCE  AND   SOIL 

plowed  soil  if  it  represented  the  average  composition  of  the  solid 
crust  of  the  earth.  Corn  is  the  most  important  American  crop, 
and  the  common  farm  practice  is  to  retain  on  the  farm  the  corn- 
stalks (stover),  so  that  the  plant  food  removed  in  the  grain  is  of 
the  greatest  consideration. 

While  there  is  probably  no  cultivated  soil  whose  composition 
is  exactly  the  same  as  the  average  of  the  earth's  crust,  and  while 
100  bushels  of  corn  per  acre  is  about  four  times  the  average  yield 
for  the  United  States,  nevertheless  the  data  given  in  Table  8  pre- 
sent the  broadest  possible  conception  of  the  great  problem  of  soil 
fertility  in  relation  to  permanent  agriculture;  because  all  soils 
are  made  essentially  from  the  earth's  crust,  and,  if  some  are  richer, 
others  are  certainly  poorer,  than  this  general  average.  Likewise 
the  loo-bushel  yield  of  corn  is  of  immediate  interest,  for  it  has  been 
produced,  —  and  can  be  produced  throughout  the  corn  belt  in 
normal  seasons  with  good  farming  on  the  richest  and  best-treated 
soils;  and  the  production  of  large  yields  is  an  essential  considera- 
tion, both  from  the  standpoint  of  profitable  farming  and  for  the 
future  support  of  a  rapidly  increasing  population. 

There  are  natural  agencies  which  may  operate  under  different 
conditions  to  enrich,  deplete,  or  maintain  the  fertility  of  the  soil. 

In  the  formation  of  residual  soils  from  the  leaching  of  disinte- 
grating and  decomposing  rock  materials,  as  illustrated  in  Tables  4 
and  5,  the  percentage  of  a  given  plant-food  element  may  increase 
or  decrease  or  remain  constant,  depending  upon  whether  the 
compound  in  which  that  element  occurs  is  proportionately  less 
or  more  soluble  than  the  bulk  of  the  material.  Thus  in  the  decom- 
position of  gneiss  (Table  4),  it  is  evident  that  the  alkali  bases,  as 
potassium,  magnesium,  calcium,  and  sodium,  were  leached  out 
much  more  rapidly  than  the  iron,  aluminum,  silicon,  and  phos- 
phorus; and  consequently  the  per  cent  of  phosphorus  doubled  and 
the  per  cent  of  potassium  and  magnesium  markedly  decreased, 
while  the  calcium  practically  disappeared.  On  the  other  hand,  in 
the  formation  of  residual  clay  from  limestone  (Table  5),  the  per 
cent  of  phosphorus  decreased  distinctly  and  the  per  cent  of  calcium 
very  greatly,  while  most  of  the  elements  in  the  silicate  minerals, 
including  potassium  and  sodium,  very  markedly  increased  in  per- 
centage. 


SOIL   COMPOSITION  61 

In  level  upland  areas,  such  as  the  loess-covered  prairies  of  the 
Central  West,  which  neither  receive  deposits  from  overflow  nor 
lose  partially  depleted  soil  by  erosion  (especially  while  covered  by 
prairie  grasses),  the  operation  of  the  natural  laws  tends  steadily 
toward  soil  depletion,  with  respect  to  the  valuable  mineral  elements; 
and  this  law  has  been  in  operation  since  the  glacial  age,  or  since 
the  loess  was  deposited,  wherever  the  climatic  conditions  have  been 
similar  to  those  prevailing  in  historic  time.  Thus  we  find  (as 
hereinafter  shown)  that  the  oldest  glacial  or  loessial  soils  (as  in 
the  lower  Illinoisan  glaciation)  are  markedly  poorer  in  total  phos- 
phorus, potassium,  magnesium,  and  calcium  than  are  the  simi- 
larly formed  soils  of  more  recent  formation  (as  in  the  late  Wiscon- 
sin glaciation).  With  some  elements  the  difference  is  most  marked 
in  the  surface  soil,  and  with  others  in  the  subsoil. 

The  accumulation  of  organic  matter  in  the  glacial  or  loessial 
soil  begins  sometime  after  its  deposition  and  continues  until  a 
maximum  is  reached,  after  which  the  organic  matter,  as  well  as 
the  valuable  mineral  elements,  tends  to  decrease,  the  latter  because 
of  leaching,  as  from  the  beginning,  and  the  former  because  the  rate 
of  decay  finally  exceeds  the  rate  of  growth  or  accumulation. 
Ultimately,  under  these  natural  processes,  the  level  lands  would 
become  practically  barren.  All  of  the  level  upland  soils  of  southern 
Illinois  were  far  past  the  maximum  in  productive  power  when  this 
country  was  first  settled.  Indeed,  much  of  the  land  of  central  and 
northern  Illinois  was  past  the  maximum  and  tending  toward 
depletion.  Probably  the  black  clay  loam  soil  of  the  flat  prairie 
lands  in  the  Wisconsin  glaciation  was  almost  at  its  maximum 
condition  of  productiveness  when  the  White  Man  took  possession, 
but  even  the  soil  of  this  topography  (drab  silt  loam)  was  far  past 
its  prime  in  the  lower  Illinoisan  glaciation. 

In  some  of  the  Southern  states  there  are  still  to  be  found  level 
upland  virgin  soils  that  are  known,  as  a  class,  to  be  too  unproduc- 
tive to  justify  cultivation.  The  author  has  collected  representative 
samples  of  this  class  of  virgin  gray  silt  loam  soils  that  were  found 
upon  analysis  to  contain  less  than  400  pounds  of  total  phosphorus 
in  2  million  pounds  of  surface  soil,  while  the  subsoil  of  adjoining 
moderately  productive  slopes  contained  1500  pounds  of  phos- 
phorus. The  carbonates  of  calcium  and  magnesium  have  entirely 


62  SCIENCE  AND   SOIL 

disappeared  from  these  level  upland  soils,  and  in  their  place  marked 
acidity  has  developed.  Under  these  conditions  the  growth  of  vege- 
tation and  the  fixation  of  nitrogen  by  legumes  become  very  lim- 
ited, and  level  virgin  soil,  not  subject  to  erosion,  was  found  to 
contain  less  than  one  fifth  as  much  as  the  average  nitrogen  content 
of  the  black  clay  loam  of  the  late  Wisconsin  glaciation  in  northern 
Illinois. 

In  the  progress  of  geologic  time,  surface  drainage  courses  are  de- 
veloped, and  all  level  uplands  become  eroded  hills  and  valleys,  thus 
exposing  the  lower  subsoils  with  their  larger  supplies  of  unleached 
mineral  plant  food,  more  or  less  of  which  is  spread  out  over  the 
lower  lying  slopes  or  level  bottom  lands,  which  sometimes  again 
become  depleted,  as  broad  terraces  above  the  deepened  channel. 

Thus,  moderate  soil  erosion  is  not  an  unmixed  evil;  and,  with  no 
adequate  return  of  mineral  plant  food,  the  bottom  lands  and  the 
sloping  hill  lands  are  more  permanently  productive  (with  legumes 
made  prominent  in  the  crop  rotations)  than  are  the  level  upland 
soils,  It  is  doubtful  if  there  has  ever  been  a  land  on  the  face  of  the 
earth,  where  the  same  soil  particles  have  been  turned  with  the  plow 
year  after  year,  that  has  remained  productive  for  two  centuries, 
with  no  return  of  mineral  plant  food.  Even  in  populous  China 
there  are  many  level  upland  areas,  sometimes  of  a  hundred  square 
miles  in  extent,  where  no  one  lives;  and  the  restoration  of  these 
areas  has  been  called  the  "  Problem  of  China." 

"  In  nature  all  things  are  in  equilibrium  "  is  often  stated  as  though 
it  were  a  self-evident  fact.  So  far  as  the  soil  is  concerned,  the  oppo- 
site is  essentially  true,  —  that,  in  nature,  there  is  no  equilibrium. 
Thus  an  ancient  forest  land  now  lies  from  10  to  300  feet  beneath 
the  Illinois  black  prairie,  which  covers  the  unweathered  glacial 
drift  of  the  most  southern  lobe  of  the  Wisconsin  glaciation. 

It  is  of  first  importance  that  the  man  who  controls  land,  and  who 
is  thus  responsible  for  its  future  productive  power,  should  have 
sufficient  fundamental  knowledge  concerning  the  composition  of 
common  soils  and  the  plant-food  requirements  of  common  staple 
crops  to  furnish  him  a  foundation  of  absolute  facts  on  which  to 
build  possible  systems  of  permanent  agriculture.  Because  of  this 
need,  considerable  space  is  devoted  to  the  ultimate  composition 
of  soils  as  they  exist  on  the  earth  to-day. 


SOIL   COMPOSITION 


First,  in  comparison  with  the  average  composition  of  the  earth's 
crust,  and  as  a  good  basis  of  comparison  for  all  other  soils,  let  us 
consider  the  total  nitrogen,  phosphorus,  and  potassium  in  the 
unmanured  land  on  the  Rothamsted  Experiment  Station  at  Har- 
penden,  England.  In  2  million  pounds  (6f  inches  per  acre)  of  the 
surface  soil  where  a  four-year  crop  rotation  of  wheat,  turnips, 
barley,  and  clover  (or  beans)  has  been  followed  for  60  years,  there 
are  found,  in  round  numbers,  2500  pounds  of  nitrogen,  1000  pounds 
of  phosphorus,  and  35,000  pounds  of  potassium.  These  are  num- 
bers worth  keeping  in  mind. 

In  Table  9  is  given  the  composition  of  four  different  soils,  of 
which  two  (from  Holland  and  Scotland)  are  extremely  productive, 
and  the  other  two  (from  Germany  and  Maryland)  are  nonpro- 
ductive soils  from  barren  lands. 

The  first  is  an  analysis  by  Baumhauer  of  a  fertile  alluvial  soil 
near  the  Zuider  Zee,  and  the  second  is  Anderson's  analysis  of  rich 
wheat  soil  of  Midlothian. 

The  third  analysis,  by  Johnson,  is  said  to  represent  "  the  most 
sterile  soil  in  Bavaria,"  and  the  last,  by  Veitch,  represents  the 
"  barrens  "  of  southern  Maryland. 

TABLE  9.   COMPOSITION  OF  SOILS 
Pounds  in  2  Million  (per  Acre  about  6f  Inches  Deep) 


PLANT  FOOD 

VERY  PRODUCTIVE  SOILS 

NONPRODUCTIVE  SOILS 

Holland 
Alluvium 

Scotland 
Wheat  Soil 

German 
Barrens 

Maryland 
Barrens 

Phosphorus  

4IOO 
17040 
1560 
58460 
132340 
7160 

3780 
5880 
12980 
17560 
72420 
360  (?) 

trace 
none 
trace 
1380 
22960 

180 

20OO 
840 
580 
17500 

Potassium    
Magnesium  

Calcium  

Iron    

These  analyses  are  given  to  show  that  the  supply  of  plant  food 
in  the  soil  is  sometimes  the  great  factor  of  difference  between 
productive  and  nonproductive  land;  but  the  fact  should  not  be 
overlooked  that  in  other  cases  other  factors  may  also  be  important 
(as  excess  or  deficiency  of  moisture,  poor  physical  condition, 


64  SCIENCE   AND   SOIL 

absence  or  inactivity  of  soil  organisms,  or  the  presence  of  injurious 
substances). 

Compared  with  the  average  crust  of  the  earth  (Table  8),  these 
two  fertile  soils  are  both  characterized  by  their  high  phosphorus 
content.  The  Holland  soil  is  low  in  magnesium,  and  the  Scotland 
soil  is  low  in  potassium,  when  compared  with  the  earth's  crust, 
although  when  compared  with  the  phosphorus  supply  and  with 
crop  requirements,  a  somewhat  different  view  is  presented.  It  is 
fair  to  raise  the  question  whether  the  sulfur  reported  for  the 
Scotland  soil  represents  the  total  or  only  the  nonvolatilerbecause 
this  soil  contained  more  than  10  per  cent  of  organic  matter,  and  it 
is  now  known  that  most  of  the  sulfur  may  be  lost  in  the  ignition 
of  such  a  soil. 

The  analysis  of  the  German  soil  reports  "  insoluble  silicates," 
and  probably  the  amounts  given  are  for  plant  food  soluble  in  strong 
acid,  but  Veitch's  analysis  of  the  Maryland  soil  represents  total 
amounts,  determined  by  the  fusion  process.  It  will  be  seen  that 
the  Holland  soil  contains  eight  times  as  much  potassium,  twenty- 
three  times  as  much  phosphorus,  and  a  hundred  times  as  much 
calcium  as  the  Maryland  soil. 

The  first  requisite  for  a  good  soil  is  that  it  shall  be  rich  in  plant 
food,  but  it  should  always  be  remembered  that  that  provision 
alone  does  not  insure  large  crops,  nor  does  a  large  stock  of  goods 
in  the  merchant's  store  to-day  insure  a  good  business  for  him 
to-morrow. 

In  this  connection,  we  may  refer  to  the  analysis  of  residual  clay 
from  slightly  phosphatic  limestone,  shown  in  Table  5,  with  i.n  per 
cent  of  phosphorus,  which  amounts  to  22,200  pounds,  or  more  than 
ii  tons,  of  phosphorus  per  acre  in  a  6f-inch  stratum  of  2  million 
pounds'  weight.  Other  soils  abnormally  high  in  phosphorus  are 
found  in  the  phosphate  regions  of  Tennessee  and  Central  Ken- 
tucky. Thus,  Mooers  (Tennessee  Bulletin  78)  reports  the  analysis 
of  an  upland  soil  and  a  bottom-land  soil,  from  near  Pulaski,  Giles 
County,  Tennessee,  showing  13,200  and  14,800  pounds,  respec- 
tively, of  phosphorus  per  acre  in  a  6f-inch  stratum  (2  million 
pounds) ;  and  analyses  by  Peter  and  Averitt  (Kentucky  Bulletin  126) 
show  12,100  pounds  and  12,400  pounds  of  phosphorus  in  2  million 
pounds  of  the  surface  and  subsurface,  respectively,  of  soil  from 


SOIL   COMPOSITION 


near  Midway,  Woodford  County,  Kentucky,  and  15,330  pounds 
and  14,800  pounds  of  phosphorus  in  2  million  pounds  of  surface 
soil  from  two  fields  near  Tebb's  Station,  Clark  County,  Kentucky. 

On  the  farm  of  the  Kentucky  Agricultural  Experiment  Station 
at  Lexington,  Fayette  County,  the  surf  ace  soil  contains  15,000 
pounds  of  phosphorus  per  acre  in  a  6f-inch  stratum,  and  the  lower 
subsoil  contains  100,000  pounds  of  phosphorus  in  2  million  of 
earth.  In  other  words,  the  lower  subsoil  between  40  and  80  inches 
contains,  as  an  average,  about  5  per  cent  of  the  element  phosphorus, 
equivalent  to  25  per  cent  of  tricalcium  phosphate.  Notwith- 
standing the  occasional  existence  of  such  abnormal  soils,  the 
more  common  soils  even  of  Kentucky  and  Tennessee,  outside  of  the 
limestone  or  phosphate  regions,  are  very  deficient  in  phosphorus. 

Four  samples  of  residual  limestone  soils  from  tobacco  planta- 
tions about  35  miles  southwest  of  Havana,  Cuba,  were  found  to 
contain  as  an  average  4790  pounds  of  acid-soluble  phosphorus  in 
2  million  pounds  of  soil.  (Frear,  Penn.  Report,  1901.) 

In  Table  10  is  shown  the  composition  of  adobe  soil  from  New 
Mexico  and  "  the  characteristic  red  earth  from  the  decomposition 
of  coralline  limestone  on  the  Islands  of  Bermuda  "  (Merrill). 

TABLE  10.   COMPOSITION  OF  ADOBE  AND  CORAL  LIMESTONE  SOILS 
Pounds  in  2  Million  of  Soil  (per  Acre  about  6f  Inches  Deep) 


CONSTITUENTS 

ADOBE  Son., 
NEW  MEXICO 

CORAL  LIMESTONE  Son., 
BERMUDA  ISLANDS 

Phosphorus    

8200 

C4OO 

Potassium       

28600 

2OOO 

Magnesium     

7^600 

^800 

Calcium     

198800 

5O2OO 

Iron       

71600 

I724OO 

Sulfur 

C2OO 

Silicon        

4IO2OO 

?  76800 

Aluminum      

I  7O6OO 

I4S6OO 

Sodium      

8800 

80 

2OOO 

Carbonate  carbon    

46600 

12300 

Water  of  hvdration       

76800 

324600 

Volatile      

68600 

224200 

Oxygen,  etc  

887600 

680780 

66  SCIENCE  AND   SOIL 

These  abnormal  soils  are  likewise  characterized  by  a  high  phos- 
phorus content.  The  coral  soil  is  also  abnormal  in  its  extremely 
low  potassium  content,  when  compared  with  ordinary  soils. 

Leather  reports  the  average  acid-soluble  phosphorus  of  the 
"  black  cotton  soils  "  of  India  as  520  pounds  in  2  million  of  soil, 
and  the  analyses  of  eighteen  other  types  of  Indian  soils  show  the 
phosphorus  as  varying  from  a  "  trace  "  to  790  pounds;  while 
among  the  other  four  types  described  by  him,  one  abnormal 
soil  (essentially  an  iron  ore)  contained  34.10  per  cent  of  iron  and 
.28  per  cent  of  phosphorus,  corresponding  to  5600  pounds  of  phos- 
phorus per  acre  in  a  6|-inch  stratum. 

Von  Ugrimov's  analyses  *  of  the  cultivated  "  black  earth  "  soil 
of  southwest  Russia  shows  only  260  pounds  of  acid-soluble  phos- 
phorus in  2  million  of  soil;  while  Hilgard 2  gives  .13  per  cent  of 
P2O5,  corresponding  to  1130  pounds  of  phosphorus  in  2  million  of 
cultivated  soil,  and  .14  per  cent  of  P2O5,  or  1220  pounds  of  phos- 
phorus, in  2  million  of  virgin  soil.  The  fact  that  the  samples  se- 
cured upon  his  request  and  analyzed  by  Hilgard  showed  5.54  per 
cent  of  humus  in  the  cultivated  soil  and  only  5.11  per  cent  in  the 
virgin  soil,  leads  one  to  question  whether  the  sample  referred  to  as 
cultivated  soil,  containing  4800  pounds  of  nitrogen,  and  acid- 
soluble  minerals  amounting  to  1130  pounds  of  phosphorus,  8600 
of  potassium,  9000  pounds  of  magnesium,  and  18,300  of  calcium 
(in  2  million  of  soil),  can  fairly  represent  the  black  earth  soil  of 
Russia  whose  average  yield  of  wheat  for  2o-year  periods  is  less  than 
10  bushels  per  acre  in  a  three- year  rotation,  including  one  year  of 
green  fallow.  (See  Bulletin  42,  Bureau  of  Statistics,  United  States 
Department  of  Agriculture.) 

The  report  of  Von  Ugrimov's  investigations  states  that  "pot  and 
field  experiments  with  wheat,  and  analyses  of  the  crop  produced, 
bear  out  the  chemical  analysis  in  indicating  that  phosphorus  is 
the  element  of  plant  food  especially  needed  in  this  soil." 

Analysis  of  "  typical  soils  "  of  British  East  Africa  shows  that 
they  are  fairly  well  supplied  with  nitrogen  and  potassium,  but 
deficient  in  phosphorus,  —  "a  deficiency  which  is  stated  to  be 
common  throughout  East  Africa."  3 

1  Experiment  Station  Record,  19,  1015.  a  "Softs,"  page  364. 

*  Experiment  Station  Record  (1908),  ig,  1015. 


SOIL   COMPOSITION  67 

Investigations  by  Ingle 1  (as  chief  chemist  for  the  Transvaal 
Department  of  Agriculture)  showed  that  "  analyses  of  Transvaal 
soils  indicate  that  they  are,  as  compared  with  English  soils,  very 
poor  in  phosphorus,  nitrogen,  and  lime,  but  usually  rich  in  po- 
tassium." 

The  Massachusetts  Experiment  Station  (Bulletin  117)  reports 
the  following  analysis  of  soil  from  Turkey,  Asia,  the  amounts  per 
acre  being  computed  for  2  million  pounds  of  surface  soil  (about 
6f  inches  deep). 

Nitrogen 06  per  cent,  or  1200  pounds  per  acre. 

Phosphorus "  none  " 

Potassium 51  percent,  or  10,200  pounds  per  acre. 

Calcium 72  per  cent,  or  14,400  pounds  per  acre. 

The  10,200  pounds  of  acid-soluble  potassium  is  probably  much 
below  the  total  potassium  present. 

Professor  J.  B.  Harrison  has  recently  reported  2  that  the  soil  of 
the  Experiment  Station  Farm  in  British  Guiana,  South  America, 
contains  43,600  pounds  of  total  potassium  in  2  million  of  soil. 
The  amount  of  phosphorus  is  not  reported. 

In  the  volcanic  ash  ejected  from  Vesuvius  during  the  eruption 
of  April  4  and  5,  i9o6,Comanducci  found  .33  percent  of  phosphorus 
and  3.87  per  cent  of  potassium,  —  amounts  which  correspond  to 
6600  pounds  of  phosphorus  and  77,400  pounds  of  potassium  in 
2  million  pounds  of  the  volcanic  material. 

The  surface  of  the  United  States  may  be  divided  into  two  areas, 
the  glaciated  and  the  unglaciated,  as  shown  on  the  accompanying 
map.  In  general,  the  great  ice  sheets  moved  from  north  to  south, 
and  as  they  flowed  slowly  over  the  face  of  the  earth,  they  caused 
enormous  erosion  of  the  surface.  The  eroded  material  was  carried 
forward  in  the  ice,  and  much  of  it  was  ground  to  powdered  form, 
while  some  was  reduced  only  to  the  form  of  rounded  bowlders, 
pebbles,  and  sand  grains.  This  mixture  embedded  in  silt  and  clay 
is  called  glacial  drift,  or  till,  or  bowlder  clay.  As  the  ice  melted, 
the  drift  material  was  deposited,  sometimes  in  moraines,  or  ridges, 
where  for  a  long  period  of  time  the  forward  movement  of  the  gla- 

1  Journal  of  Agricultural  Science,  December,  1908. 
8  West  Indian  Bulletin  (1908),  Q,  9. 


68  SCIENCE   AND   SOIL 

tier  was  practically  equaled  by  the  rapidity  with  which  the  ice 
melted  at  the  terminus,  and  sometimes  over  broad  inter-morainal 
tracts,  where  the  melting  proceeded  more  rapidly.  Many  preglacial 
valleys  were  filled  with  the  drift  (in  places  300  feet  deep),  and  com- 
monly glacial  drift  was  deposited  over  the  general  level  of  the 
glaciated  area  to  a  depth  of  10  to  100  feet. 

We  are  especially  interested  in  four  of  the  important  ice  sheets 
that  occurred  during  the  glacial  epoch.  Where  the  drift  from  the 
first  of  these  was  not  covered  by  a  subsequent  glacier,  the  area  is 
termed  the  Kansan  glaciation;  where  the  drift  from  the  second  gla- 
cier was  not  covered  by  a  subsequent  glacier,  the  area  is  termed  the 
Illinoisan  glaciation;  where  the  drift  from  the  third  glacier  was 
not  covered  by  a  subsequent  glacier,  the  area  is  called  the  lowan 
glaciation;  and  the  area  covered  by  the  drift  from  the  fourth  glacier 
is  termed  the  Wisconsin  glaciation,  where  not  covered  by  a  subse- 
quent glacier.  As  will  be  seen  from  the  glacial  map,  these  respective 
areas  are  not  confined  to  the  states  named. 

It  should  be  understood  that,  notwithstanding  the  extensive 
glaciated  regions,  glacial  soils  are  not  common  in  the  older  glaciated 
areas.  The  most  common  soil  material  between  the  Alleghanies 
and  the  Rocky  Mountains,  and  between  the  Great  Lakes  and  the 
Gulf,  is  loess. 

Loess  is  a  very  fine  material 1  consisting  of  grains  of  quartz, 
felspar,  mica,  hornblende,  and  other  granitic  or  silicate  minerals, 
with  more  or  less  limestone,  dolomite,  magnetite,  pyrite,  etc., 
and  some  clay.  Loess  has  been  derived  in  large  part  from  glacial 
drift,  having  been  transported  by  the  action  of  wind  and  flowing 
water,  probably  from  deposits  of  exposed  till  before  it  was  protected 
by  vegetation  (and  to  some  extent  from  the  melting  or  evapo- 
rating glaciers),  and  deposited  over  all  other  soil  formations  and 
over  older  glaciated  areas.  Many  of  the  residual  soils  in  the  drift- 
less,  or  unglaciated,  areas  in  the  Mississippi  Basin  are  now  covered 
with  loess.  Even  the  tops  of  the  Ozark  Hills  of  southern  Illinois, 
beyond  the  most  southern  point  of  the  glacial  lobe,  and  high  above 

1  In 'some  places  the  loess  is  more  or  less  mixed  with  the  underlying  residual 
or  glacial  materials,  through  the  action  of  crawfish,  burrowing  animals,  etc.,  and 
occasionally  loess  deposits  are  subsequently  covered  by  mixed  alluvial  materials, 
which  may  include  sand  and  gravel  with  silt,  clay,  and  organic  matter. 


167       157    147   137  127  117  107  97  87  77   67  57    47 


K.nsan  Drift 

Drift 
Imoan  Drift 

d  later  drift  sheet 
Existing  glaciers  and  ice  sheet 


MAP  OF  THE  GLACIATED  AREA  OF  NORTH  AMERICA 
From  Upham's  map  as  modified  by  Leverett,  United  States  Geological  Survey 


SOIL   COMPOSITION 


69 


the  nearest  glacial  ridges,  are  covered  with  several  feet  of  loess. 
The  older  glacial  drift  is  usually  loess-covered.  The  depth  of  loess 
varies  from  three  feet  or  less  in  the  somewhat  recent  glaciations, 
and  in  driftless  areas,  remote  alike  from  the  glacial  borders  and  from 
large  stream  courses,  to  eight  or  ten  feet  in  areas  near  the  borders 
of  the  greatest  glacial  action;  while  in  the  "deep  loess"  areas 
covering  the  bluff  lands  along  some  of  the  large  streams  the  depth 
of  loessial  material  may  be  from  ten  to  fifty  feet  or  more. 

Some  very  complete  analyses  have  been  made  of  samples  of 
loess  from  widely  separated  areas.  The  results  given  in  Table  1 1 
are  reported  by  the  United  States  Geological  Survey.  The  first 
three  represent  loess  deposits  covering  the  bluffs  at  Galena,  Illi- 
nois; Vicksburg,  Mississippi;  and  Kansas  City,  Missouri;  while 
the  fourth  "  was  taken  from  the  summit  of  a  ridge  in  the  suburbs 
of  Dubuque,  Iowa,  at  a  point  about  300  feet  above  the  Mississippi 
River." 

TABLE  n.   COMPOSITION  OF  LOESS  DEPOSITS 
Pounds  in  2  Million  of  Loess 


CONSTITUENTS 

GALENA, 
ILLINOIS 

VICKSBURG, 
MISSISSIPPI 

KANSAS  CITY, 
MISSOURI 

DUBUQUE, 
IOWA 

Phosphorus      .... 

600 

I2CO 

800 

2OOO 

Potassium    

34400 

I8OOO 

30600 

35600 

Magnesium       .... 

44400 

55000 

13400 

13400 

Calcium       

77200 

I2800O 

24200 

22800 

Ferric  iron        .... 

36600 

36600 

45400 

49400 

Ferrous  iron     .... 

8000 

I04OO 

1800 

I5OOO 

Sulfur      .     .     . 

800 

IOOO 

4OO 

4OOO 

Silicon     

606800 

«;  60800 

*fWW 

600600 

*^w 

682600 

Aluminum   

I  I  2600 

J  *^  ;/ 

84200 

w 
129800 

127400 

Sodium    

2OOOO 

174.00 

2I2OO 

24200 

Manganese       .... 

800 

/  1^^ 
1800 

4OO 

IOOO 

Titanium     

4800 

6200 

I6OO 

8600 

Carbonate  carbon      .     . 

34400 

52600 

26OO 

22OO 

Organic  carbon     .     .     . 

2600 

3800 

24OO 

I800 

Water  and  organic  hy- 

drogen       

4IOOO 

22800 

54000 

50000 

Oxygen,  etc  

Q7<OOO 

991200 

Q722OO 

960000 

y  /  j*~f*-f 

y  / 

70  SCIENCE   AND   SOIL 

These  analyses  show  the  general  range  in  composition  of  the 
mineral  material  constituting  the  bulk  of  our  most  common,  most 
extensive,  and  most  valuable  soils,  in  the  central  part  of  the  United 
States,  both  north  and  south  (along  the  Mississippi  Valley),  where, 
as  a  very  general  rule,  the  surface  is  covered  by  a  blanket  of  loess 
two  feet  or  more  in  depth. 

In  the  fresh  condition,  as  in  the  deeper  strata,  loess  usually 
contains  considerable  amounts  of  calcium  carbonate  and  more  or 
less  magnesium  carbonate,  as  is  the  case  with  the  samples  from 
Galena  and  Vicksburg,  both  of  which  are  known  to  represent  strata 
of  considerable  depth.  The  Dubuque  sample  was  evidently  taken 
from  the  surface,  and  this  may  be  the  case  with  the  Kansas  City 
sample,  in  both  of  which  the  carbonates  have  evidently  been  greatly 
reduced  by  leaching. 

As  an  average,  the  phosphorus  content  amounts  to  1150  pounds 
per  acre  for  a  stratum  of  6f  inches  (2  million  pounds) ,  including  the 
Galena  sample,  which  is  decidedly  low,  and  the  Dubuque  sample, 
which  is  abnormally  high.  The  average  of  nine  different  composite 
samples  of  subsoils  from  different  places  in  the  deep  loess  areas  in 
Illinois  shows  mo  pounds  of  total  phosphorus  in  2  million  pounds 
of  loess,  the  extreme  variation  being  from  740  to  1540  pounds. 
(See  Illinois  Experiment  Station  Bulletin  123,  pages  288-289.) 

While  phosphorus  is,  in  a  sense,  an  incidental  substance  in  loess 
deposits,  the  element  potassium  is  an  important  constituent  of  the 
most  common  original  minerals,  and  any  marked  variation  in 
potassium  content  must  be  accounted  for  largely  by  decomposition 
and  loss  by  weathering  of  the  particles,  the  chief  losses  having 
occurred  probably  before  the  accumulation  into  the  present  loessial 
deposits. 

The  average  of  the  two  northern  samples  (Galena  and  Dubuque) 
shows  35,000  pounds  of  potassium, while  the  sample  from  the  south- 
west (Kansas  City)  shows  30,600  pounds,  and  the  southern  loess 
contains  only  18,000  pounds  of  potassium  in  2  million.  If  loess  is 
derived  chiefly  from  glacial  drift,  as  viewed  by  the  United  States 
Geological  Survey  (38th  Monograph,  page  159),  then  it  would  be 
expected  that  the  southern  loess,  transported  far  from  glacial  de- 
posits, would  be  lower  in  potassium  than  the  northern  loess,  which 
has  been  less  exposed  to  weathering.  As  an  average  of  the  nine 


SOIL   COMPOSITION  71 

composite  samples  of  subsoil  from  different  places  in  the  deep 
loess  areas  of  Illinois,  35,070  pounds  of  potassium  were  found  in 
2  million  of  loess. 

In  the  loess  which  was  not  mixed  with  carbonates,  or  from  which 
most  of  the  carbonates  have  been  removed,  presumably  by  leach- 
ing (Dubuque  and  Kansas  City  samples),  the  total  supply  of  mag- 
nesium and  calcium  is  markedly  smaller  than  the  supply  of  potas- 
sium; but  when  compared  with  the  average  requirements  of  a 
general  crop  rotation  (see  Table  13)  the  supply  of  magnesium  and 
calcium  is  still  somewhat  more  ample  than  that  of  potassium. 

While  the  average  supplies  of  sulfur  and  phosphorus  are  about 
equal,  the  requirement  for  phosphorus  is  five  times  as  great  as  for 
sulfur  in  the  total  produce  of  the  average  crop  rotation,  and  forty 
times  as  great  if  the  grain  only  is  removed  and  not  returned. 

A  partial  analysis  of  loess  from  Cheyenne,  Wyoming,  reported 
by  Eakin,  shows,  in  2  million  pounds  of  loess,  960  pounds  of  phos- 
phorus, 44,500  of  potassium,  14,880  of  magnesium,  69,700  of 
calcium,  and  20,000  pounds  of  carbonate  carbon. 

It  is  suggested  that  most  of  the  carbonates  contained  in  deep 
loess  deposits  may  have  a  different  origin  than  the  silicates,  which 
constitute  the  bulk  of  the  material.  In  many  deep  loess  deposits, 
pieces  of  limestone  shells  (usually  of  light  weight)  are  a  characteris- 
tic, indicating  that  a  part  of  the  loessial  material  may  have  come 
from  areas  which  were  at  times  covered  with  water  and  at  other 
times  dried  on  the  surface  and  exposed  to  wind  action.  Thus, 
while  such  loess  may  have  been  derived  from  glacial  drift,  more  or 
less  of  it  has  had  some  intermediate  resting  place  where  carbonates 
tend  to  accumulate,  as  in  ponds,  shallow  lakes,  swamp  areas, 
bottom  lands,  or  on  seepy  slopes;  and  from  the  dried  surfaces  of 
such  areas  much  of  it  has  been  transported  by  wind  action  over 
bluffs  and  upland  plains.  It  is  noteworthy  that  the  broadest  deep 
loess  deposits  along  the  river  bluffs  are  found  where  the  valley  is 
correspondingly  wide  (Illinois  Bulletin  123,  page  238). 

The  most  definite  lesson  to  be  drawn  from  these  analyses  of  this 
most  important  soil  material  is,  that  phosphorus  is  clearly  the  most 
limited  element  of  plant  food;  whereas  among  the  four  elements, 
potassium,  magnesium,  calcium,  and  sulfur,  it  is  difficult  to  de- 
termine which  is  likely  to  be  the  most  limited. 


72  SCIENCE   AND   SOIL 

SOME   EASTERN   RESIDUAL   SOILS 

In  Table  12  is  given  the  ultimate  chemical  composition  of  residual 
soils  derived  from  ten  different  geological  formations,  and  as  a 
rule  the  results  are  the  average  from  several  samples  of  the  same 
type  of  soil.  The  soils  were  collected  in  Maryland,  but  in  most 
cases  the  same  soil  types  extend  into  other  states  and  may  be  con- 
sidered as  more  widely  representative  of  these  soil  formations. 

The  soil  analyses  1  were  made  by  Mr.  F.  P.  Veitch  of  the  United 
States  Department  of  Agriculture,  under  the  direction  of  Professor 
Milton  Whitney,  Chief  of  the  Bureau  of  Soils,  and  with  the  indorse- 
ment of  Doctor  H.  W.  Wiley,  Chief  Chemist  of  the  Department  of 
Agriculture. 

In  all  cases  the  samples  analyzed  were  taken  "  immediately 
under  the  top  soil,"  and  thus  represent  the  upper  stratum  of  the 
subsoil.  The  results  are  given  in  Table  12  on  the  basis  of  pounds 
of  the  different  elements  present  in  2  million  pounds  of  the  soil, 
corresponding  approximately  to  the  amounts  per  acre  in  a  6f -inch 
stratum.  "  Volatile  "  means  loss  on  ignition,  and  includes  organic 
matter,  combined  water,  probably  some  sulfur,  which  may  be 
oxidized  from  organic  matter  or  from  pyrites,  and  possibly  some 
carbon  dioxid  (not  completely  replaceable  if  derived  from  magne- 
sium carbonate).  Oxygen  may  be  lost  or  gained  during  ignition, 
depending  upon  the  compounds  of  iron,  sulfur,  etc.,  the  amount 
of  organic  matter,  and  the  stage  to  which  the  ignition  is  carried. 
The  oxygen  is  estimated  by  difference,  which  really  includes  errors 
and  all  undetermined  elements  not  otherwise  reported. 

It  should  be  kept  in  mind  that  sandstone  does  not  mean  quartz. 
It  means  a  stone  with  sand  grains  cemented  together.  The  sand 
grains  may  consist  of  quartz  (silicon  dioxid),  but  more  commonly 
they  are  grains  of  silicate  minerals,  including  much  aluminum  and 
iron  and  more  or  less  of  the  other  abundant  mineral  elements. 
Residual  soils  resulting  from  the  disintegration,  decomposition, 
and  leaching  of  the  previous  geological  formations  vary  with  the 
character  of  the  original  rock,  and  with  the  loss  by  leaching.  In  the 
case  of  the  limestone  formations,  it  is  apparent  that  the  residual 
soil  consists  of  impurities  contained  in  the  original  limestone,  the 

1  Maryland  Agric.  Expt.  Station  Bulletin  70. 


SOIL   COMPOSITION 


73 


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04     O    VO 

O    O    O  OO 

O    vo 

a 

M      t^. 

ONOO  00 

t—  1     ^"  OO     CS 

OO    w 

<N 

f*5        vO 

•*   -^-   M 

ON  •sf 

c^ 

VO     H 

ON 

1 

8| 

O    O    O    O 

o  o  o  •<*• 

8  88« 

O    O 

o  ^t- 

-s 

»o 

o  *•»  o  ^ 

•<too    cs    2 

O      HI 

vo  •* 

o 

HI 

HI               CS 

HI     VO    HI      C 

M 

vo  <s 

HI    OO 

.a 

J8 

o  o  o  o 

O    O    O  00 

80  o  o 
000 

0    O 

O  00 

*C 

O  vO    ^1"  fO 

•*•  O    O  vO 

O  vo 

o< 

t^  VO   t^-    HI 

ON  t~"*  t^>  HI 

^f  vo 

o 

CS 

HI    OO 
VO      HI 

CS     CS 

HI    ON 

CONSTITUENTS 

Phosphorus  . 
Potassium 

1  ... 

wo  c  ,5 
'4  A  23 

^OHHCO 

Silicon  .  . 
Aluminum  . 
Sodium  .  . 
Manganese  . 

"S 

~    cu 

Id 

74  SCIENCE  AND   SOIL 

carbonates  of  calcium  and  magnesium,  which  may  have  con- 
stituted 75  to  90  per  cent  or  more  of  the  original  rock,  having  been 
nearly  or  completely  dissolved  out  (see  Table  5). 

Two  striking  facts  are  revealed  by  the  analyses  of  these  ten  soils 
from  ten  different  geological  formations: 

1.  The  amount  of  phosphorus  is  very  small  compared  with  the 
requirements  of  large  crops  for  many  years,  the  amount  varying 
from  720  pounds  in  the  Gabbro  soil  to  1500  pounds  in  the  Helder- 
berg  limestone  soil.  Counting  17  pounds  of  phosphorus  for  100 
bushels  of  corn,  the  720  pounds  would  be  sufficient  for  only  43 
such  crops;  or,  if  both  grain  and  stalks  are  removed  from  the  land 
and  if  one  pound  of  phosphorus  per  acre  is  the  yearly  loss  in  drain- 
age water,  the   720  pounds  is  sufficient  for  only  30  such  crops; 
while  the  best  soil  contains  sufficient  total  phosphorus  in  a  61- 
inch  stratum  for  only  63  such  crops.  The  average  of  the  ten  soils 
shows  1 1 oo  pounds  of  phosphorus  in  two  million  pounds  of  soil, 
or  about  one  half  as  much  as  in  the  average  crust  of  the  earth. 

2.  The  amount  of  potassium  is  very  large,  varying  from  20  to 
50  times  as  much  as  the  phosphorus.  The  15,400  pounds  of  po- 
tassium in  6f  acre  inches  of  the  poorest  soil  would  be  sufficient 
for  100  bushels  of  corn  every  year  for  800  years,  while  the  57,400 
pounds  in  the  best  soil  would  suffice  for  3000  years,  if  it  could  be 
made  available  as  needed  and  if  only  the  grain  were  removed. 
If  both  grain  and  stalks  were  removed,  these  supplies  are  sufficient 
for  200  and  800  crops,  respectively,  counting  19  pounds  of  potas- 
sium for  ico  bushels  of  corn  and  52  pounds  for  the  stalks  for  such 
a  crop,  not  including  the  loss  in  drainage,  which,  however,  would  be 
somewhat  greater  than  for  phosphorus.    Six  of  these  soils  average 
nearly  as  rich  in  potassium  as  the  earth's  crust,  while  the  poorest 
soil  is  about  one  third  as  rich. 

Several  of  these  soils  are  less  abundantly  supplied  with  magne- 
sium and  calcium  than  with  potassium,  not  only  in  total  amounts, 
but  also  in  comparison  with  the  requirements  of  some  general  farm 
crops.  In  some  cases  the  soils  contain  less  than  one  third  as  much 
magnesium,  and  less  than  one  fifth  as  much  calcium,  as  potassium; 
while  corn  contains  more  than  one  third  as  much  magnesium  as 
potassium,  and  clover  hay  contains  almost  as  much  calcium  as 
potassium,  and  one  fourth  as  much  magnesium  (see  Table  13). 


SOIL   COMPOSITION  75 

TABLE  13.  MINERAL  PLANT  FOOD  IN  WHEAT,  CORN,  OATS,  AND  CLOVER 


PRODUCE 

p^ 
11 

a,-, 
|| 

in  3 

s 

J3-*-x 

Bl 

s  ^~* 
o-S 

0  ° 

sf 

If 

Kind 

Amount 

SI 

fi 

$£ 

0°-i 
PH^ 

11 

<0n 
S^ 

3% 
ufe 

11 
fc 

11 

COflj 

Wheat      .... 
Wheat  straw      .     . 

Corn    

50    bu. 
2\  tons 

100    bu. 

12 

4 
17 

13 

45 

IQ 

4 
4 
7 

I.O 

9-5 
i  "? 

•3 
i-5 

.A 

.1 

2.O 
2 

Corn  stover  .     .    . 
Oats    

3    tons 
100    bu. 

6 
II 

52 

16 

10 

A 

21.  0 

2  O 

4-8 

e 

5-8 
6 

Oat  straw     .     .    . 

2^  tons 

5 

52 

7 

15-0 

2.8 

3-° 

Clover  hay    . 

4    tons 

20 

3 
1  20 

31 

•5 
117.0 

4.0 

6.4 

Total  in  four  crops 

77 

320 

68 

168. 

14-3 

15.2 

Note  the  accumulation  of  phosphorus  in  the  grain  and  straw  and 
compare  with  potassium  and  with  sulfur;  also  compare  magnesium 
and  calcium  in  this  respect. 

OTHER   EASTERN   SOILS 

By  the  action  of  the  different  agencies  of  transportation,  soil 
particles  are  often  sorted  into  grades,  as  clay,  silt,  sand,  and  gravel, 
and  in  addition  there  are  stony  loams  and  other  residual  soils,  and 
the  cumulose  soils  (as  peaty  soils),  which  accumulate  in  swamps 
and  bogs  and  consist  largely  of  plant  residues. 

In  Table  14  is  recorded  a  valuable  series  of  analyses  from  the 
Cornell  Experiment  Station  (Roberts'  "  Fertility  of  the  Land," 
1900,  page  13),  representing  "  the  amounts  of  plant  food  in  surface 
soils  in  New  York  State." 

TABLE  14.   COMPOSITION  OF  SURFACE  SOILS  IN  NEW  YORK  STATE 
Pounds  in  2  Million  (per  Acre  about  6f  Inches  Deep) 


Son,  TYPE 

No.  OF 
ANALYSES 

TOTAL 
NITROGEN 
POUNDS 

TOTAL 
PHOSPHORUS 
POUNDS 

TOTAL 
POTASSIUM 
POUNDS 

Clay  loam    

II 

2060 

1360 

234QO 

Loam       

8 

^480 

1480 

3O2IO 

Sandy  loam       
Gravelly  loam  
Slaty  loam    

8 
10 

i 

2500 
5480 
3OOO 

1440 
2170 
IS7O 

32620 
26640 
29050 

Peaty  soil     

2 

•5          , 

22CKO 

1800  l 

3280' 

1  Amounts  in  i  million  pounds. 


76  SCIENCE  AND   SOIL 

These  New  York  soils  are  somewhat  richer  in  phosphorus  than 
most  of  the  older  residual  soils,  and  noticeably  richer  than  the 
average  loessial  soils  of  the  older  formations. 

The  ten  samples  of  gravelly  loam  show  an  average  phosphorus 
content  of  2170  pounds  in  2  million  of  soil,  which  is  about  the  same 
as  the  average  of  the  earth's  crust. 

With  one  notable  exception  these  soils  are  very  rich  in  potassium, 
although  not  quite  equal  to  the  average  loessial  soils  of  the  corn 
belt. 

Two  of  the  common  New  York  soils  (loam  and  gravelly  loam) 
exceed  5000  pounds  per  acre  in  the  nitrogen  content  of  the  surface 
6f  inches,  an  amount  which  represents  approximately  the  average 
of  the  most  abundant  prairie  soils  of  the  corn  belt,  while  the  three 
soils,  clay  loam,  sandy  loam,  and  slaty  loam,  contain  about  one 
half  as  much. 

In  the  peaty  soil  we  find  another  very  abnormal  soil  type,  which 
it  is  instructive  to  compare  with  the  barren  soils  of  Germany  and 
Maryland,  with  the  depleted  long-cultivated  soils  of  India,  Turkey, 
Russia,  and  Africa,  with  the  coral  limestone  soil  of  the  Bermuda 
Islands  and  the  limestone  soils  of  Cuba,  and  with  the  phosphatic 
soils  of  Tennessee  and  Kentucky.  The  peaty  soil  contains  in  a 
6f -inch  stratum  nearly  ten  times  as  much  nitrogen,  nearly  twice  as 
much  phosphorus,  and  only  one  tenth  as  much  potassium  as  the 
general  average  of  the  most  common  American  soils. 

The  soil  on  the  Experiment  Station  farm  at  the  State  College, 
Pennsylvania,  contains  2320  pounds  of  total  nitrogen,  1080  pounds 
of  acid-soluble  phosphorus,  and  5600  pounds  of  acid-soluble  po- 
tassium, in  2  million  pounds  of  the  surface  soil  (Frear,  Penn.  Dept. 
Agr.  Report,  1906).  While  most  of  the  phosphorus  is  usually 
soluble  in  the  acid  used  (HC1  of  1.115  sp.  8r-)>  on^y  about  one 
sixth  of  the  total  potassium  contained  in  old  soils  is  thus  dissolved, 
as  a  general  average,  although  the  proportion  varies  greatly  with 
different  types  of  soil.  Doctor  Frear  has  subsequently  furnished 
data  showing  that  2  million  pounds  of  the  fine  earth  in  the  surface 
soil  on  the  Pennsylvania  State  College  farm  contain  50,700  pounds 
of  total  potassium. 


SOIL   COMPOSITION  77 

SOILS   OF   THE   CENTRAL   STATES 

The  accompanying  soil  map  of  Illinois  and  Tables  15,  16,  and  17 
serve  to  illustrate  in  a  very  trustworthy  manner  both  the  uniform- 
ity and  variation  that  may  be  expected  among  the  most  important 
soil  types  in  the  North  Central  States.  This  detailed  information 
from  Illinois  applies  with  almost  equal  value  to  similar  soils  in 
many  other  states.  With  a  north  and  south  extension  of  nearly 
400  miles  in  the  center  of  the  greatest  agricultural  region  of  the 
United  States,  Illinois  occupies  a  unique  position.  In  latitude  it 
reaches  almost  from  Vermont  to  North  Carolina,  Cairo  being  farther 
south  than  Richmond,  and  Beloit  farther  north  than  Boston. 
Cairo  is  within  35  miles  of  the  Tennessee  line,  and  150  miles  south 
of  Covington,  Kentucky.  From  Cairo  to  Mobile  on  the  Gulf  is 
no  farther  than  from  Beloit  to  the  49th  parallel,  which  marks  the 
northern  boundary  of  the  United  States.  The  soils  of  Illinois  are 
in  large  measure  representative  of  the  soils  of  the  wheat  belt,  of 
the  corn  belt,  and,  in  part,  of  the  cotton  belt.  Cotton  growing  has 
been  a  commercial  success  in  southern  Illinois,  and  much  spring 
wheat  has  been  produced  in  the  north  end  of  the  state,  while  central 
Illinois  is  the  heart  of  the  corn  belt. 

Fourteen  great  soil  areas  are  recognized  in  Illinois,  including  the 
extensive  unglaciated  regions  in  the  southern  and  northwestern 
parts  of  the  state,  the  lower,  middle,  and  upper  Illinoisan  glacia- 
tions,  the  pre-Iowan  and  lowan  glaciations,  the  early  and  late 
Wisconsin  glaciations,  with  numerous  moraines  and  intermorainal 
tracts,  the  deep  loess  deposits,  and  the  early  and  late  swamp  and 
sand  areas,  and  extensive  and  widely  distributed  bottom  lands  and 
terraces. 

As  already  explained,  the  material  called  loess  constitutes  the 
chief  basis  for  nearly  all  of  the  upland  soils  of  central  United  States. 
The  principal  differences  among  these  soils  of  loessial  origin  are  due 
to  difference  in  age,  topography,  and  climatic  conditions.  Some 
additional  or  subsequent  differences  have  been  brought  about  by 
variation  in  native  vegetation  and  in  systems  of  farming. 

Prairie  and  timber  soils.  The  upland  soils  may  be  divided  into 
prairie  soils  and  timber  soils,  according  to  the  character  of  the 
original  vegetation;  and  with  similar  topography  the  difference  in 


78  SCIENCE  AND   SOIL 

vegetation  is  not  due  to  original  differences  in  the  soil  materials ; 
but  rather  the  difference  between  prairie  land  and  timber  land  is 
due  to  the  influence  of  the  vegetation  upon  the  soil.  The  existence 
of  prairies  over  areas  naturally  well  surface-drained  is  due  very 
largely,  if  not  entirely,  to  the  prairie  fires,  which  were,  as  a  rule,  of 
annual  occurrence  and  often  a  source  of  danger  to  the  early  settlers 
in  prairie  regions. 

The  annual  destruction  of  any  seedlings  that  may  have  started 
effectually  prevented  the  growth  of  forests  on  the  prairie  lands, 
and  it  is  noteworthy  that  level  areas  or  valleys  on  the  northeast 
side  of  streams  were  usually  timbered,  while  corresponding  areas 
on  the  southwest  were  usually  prairie,  because  of  the  prevailing 
southwest  winds  during  summer  and  autumn.  (See  "  Soils  of  Clay 
County,  Illinois.")  Prairie  fires  have  no  tendency  to  run  down  hill, 
and  they  make  but  little  progress  against  the  wind. 

The  wild  prairie  grasses  and  weeds,  including  native  legumes, 
developed  an  abundant  root  system  to  an  average  depth  of  16  to 
20  inches,  varying  somewhat  with  the  latitude  or  length  of  season, 
the  depth  being  greater  in  the  latitude  of  central  Illinois  than  in 
northern  Illinois;  and,  with  the  partial  decay  of  these  roots, 
followed  the  marked  accumulation  of  humus  which  characterizes 
the  "  black  soil  "  of  the  prairie;  while  the  smaller  amount  of  humus 
is  the  chief  characteristic  of  the  timber  soils.  Rotting  tree  roots 
are  subject  to  very  complete  decay,  because  of  the  large  cavities 
and  ready  admission  of  air.  Boring  insects  and  burrowing  animals 
also  hasten  the  destruction,  so  that  the  small  amount  of  leaf  mold 
that  remains  constitutes  the  main  source  of  humus  for  timber 
soils,  and  even  this  is  exposed  to  rapid  decay.  Being  poorer  in 
organic  matter,  the  upland  timber  soils  are  correspondingly  poorer 
in  nitrogen  than  the  prairie  soils. 

The  prairie  lands  may  be  classified  according  to  topography, 
as  undulating  prairies  and  flat  prairies. 

The  undulating  prairie  soil  covers  the  nearly  level  or  gently 
rolling  prairie  lands  that  were  naturally  fairly  well  surface-drained. 
It  is  usually  markedly  uniform  in  a  given  formation,  and  consti- 
tutes the  most  important  soil  of  the  corn  belt.  More  or  less  of  the 
clay  and  finer  silt  has  been  carried  downward  from  the  surface  and 
accumulated  in  the  subsoil,  and  some  has  been  carried  away  by 


SOIL   COMPOSITION  79 

surface  washing  during  many  centuries  and  collected  in  lower 
lying  flat  areas.  The  exposure  of  the  surface  after  the  annual 
prairie  fires  permitted  some  slight  surface  washing  which  other- 
wise would  not  have  occurred. 

The  flat  prairie  soils  occupy  the  lower  lying  level  areas  that  were 
naturally  poorly  surface-drained  and  inclined  to  be  swampy,  espe- 
cially during  the  wet  season  of  the  year.  This  soil  has  been  formed 
in  part  from  deposits  of  fine  earth  and  vegetable  matter  washed  in 
from  the  surrounding  higher  land.  The  rank  growing  swamp 
grasses  have,  from  the  partial  decay  of  their  roots  (and  of  more  or 
less  of  their  tops) ,  added  much  organic  matter  to  this  soil. 

The  undulating  prairie  soils  vary  from  a  gray  silt  loam  on  tight 
clay  in  the  older  areas,  to  a  dark  brown  silt  loam,  in  the  later  forma- 
tions, and  the  common  flat  prairie  soils  vary  with  age  from  drab 
silt  loam  to  black  clay  loam. 

Many  other  less  extensive  soil  types  occur  here  and  there  on  the 
prairies,  including,  as  extremes,  sand  dunes  formed  of  wind-blown 
material  from  old  shallow  lake  beds,  gravel  points,  or  exposed  glacial 
till,  bogs  of  peat  or  muck,  and  sometimes  adjoining  strips  of  plastic 
clay.  Some  intermediate  types  include  deep  silt  loam,  sandy  loam, 
silt  on  clay,  etc.  These  are  of  small  importance  compared  with 
the  very  extensive  and  most  common  prairie  soils  reported  in 
Tables  15,  16,  and  17. 

There  are  three  principal  types  of  upland  timber  soils  in  most  of 
the  great  loess-covered  areas.  One,  a  light  gray  silt  loam,  occupies 
the  flat  areas ;  a  second  type,  yellow-gray  silt  loam,  covers  the 
undulating  or  gently  sloping  lands;  and  the  third  (yellow  silt  loam) 
is  hilly  or  steeply  sloping  and  consequently  subject  to  serious  ero- 
sion, or  surface  washing,  especially  when  under  cultivation.  In 
addition,  there  are  the  areas  of  deep  loess  (yellow  fine  sandy  loam) 
covering  the  bluffs  in  many  places  along  the  larger  river  valleys; 
and  other  less  extensive  types  are  sometimes  found.  In  northern 
Illinois  and  southern  Wisconsin,  in  what  is  termed  the  lowan 
glaciation,  considerable  areas  are  found  of  a  brown  sandy  loam, 
occupying  in  the  main  the  undulating  uplands.  The  top  soil  con- 
sists of  brown  sandy  loam,  containing  some  gravel  in  places  and 
occasionally  pieces  of  stone.  The  subsoil  at  a  depth  of  three  feet 
or  more  frequently  contains  much  stone,  the  proportion  increasing 


8o  SCIENCE  AND   SOIL 

with  the  depth,  the  disintegrating  bed  rock  being  found  at  4  to  10 
feet  beneath  the  surface.  The  bed  rock  and  some  of  the  pieces  found 
in  the  soil  and  subsoil  consist  of  impure  limestone.  The  soil  is 
commonly  recognized  as  drift,  but  it  is  certainly  much  modified  by 
the  residual  material,  and  in  places  there  is  but  little  evidence  of 
glacial  or  loessial  deposit. 

Sand,  swamp,  and  bottom  lands.  In  the  older  formations,  as  in 
the  Illinoisan  glaciations  and  still  farther  south,  the  soil  of  the 
smaller  river  bottoms  is  chiefly  a  deep  gray  silt  loam;  while,  in  the 
more  recently  formed  great  soil  areas,  the  principal  bottom  land 
soil  is  a  brown  loam.  In  both  cases  the  bottom  land  resembles 
somewhat  the  top  soil  of  the  adjoining  upland  (which  has  con- 
tributed much  to  its  formation) ,  modified  by  additions  of  humus 
and  alluvium  from  other  sources.  Many  other  types  of  bottom  land 
are  also  found,  but  usually  they  are  less  abundant. 

Extensive  swamp  regions  are  found  in  most  of  the  Northern 
States,  especially  in  Michigan,  Wisconsin,  and  Minnesota,  and  in 
the  northern  parts  of  Ohio,  Indiana,  Illinois,  and  Iowa.  These 
swamp  soils  vary  almost  from  pure  sand  to  pure  clay,  and  almost 
from  100  per  cent  mineral  matter  to  100  per  cent  organic  matter; 
and  they  also  vary  from  moderately  acid  soils  to  marls  containing 
more  than  50  per  cent  of  calcium  carbonate,  and  not  infrequently 
magnesium  carbonate  is  present  in  sufficient  amount  to  render  the 
soil  non-productive  and  place  it  in  the  alkali  class.  These  different 
constituents  vary  quite  independently,  sand,  peat,  clay,  peaty  sand, 
sandy  peat,  peaty  clay  or  clayey  peat  (muck),  sandy  clay,  clayey 
sand,  loam,  sandy  loam,  clay  loam,  and  peaty  loam  being  among  the 
possible  soil  types;  and  any  of  these  may  be  acid  or  may  contain 
"  alkali."  In  addition  we  find  such  variations  as  deep  peat,  medium 
peat,  and  shallow  peat,  with  sand  or  clay  or  sandy  clay  subsoil. 
In  places  there  are  broad,  level,  and  very  uniform  areas  of  deep 
peat,  of  peat  on  sand,  or  of  nearly  pure  sand;  and  in  other  places 
peat  bogs  and  sand  ridges  alternate  every  few  rods.  Not  infre- 
quently sand  dunes  (still  subject  to  more  or  less  wind  action)  are 
found  in  or  adjoining  these  swamp  regions;  and  in  some  sections 
there  are  more  extensive  sand  regions,  including  considerable 
parts  of  counties  in  Ohio,  Indiana,  Illinois,  and  Wisconsin,  and  an 
area  of  several  counties  in  the  north  central  part  of  the  lower 
peninsula  of  Michigan. 


SOIL    COMPOSITION  81 

In  case  of  the  most  important  soil  types  the  averages  reported 
in  Tables  15,  16,  and  17  are  based  upon  analyses  of  a  large  number 
of  composite  soil  samples.  The  two  most  extensive  soil  types  in 
Illinois  are  the  gray  silt  loam  prairie  (330)  of  the  lower  Illinoisan 
glaciation  (the  so-called  hard-pan  soil  of  "Egypt"),  and  the 
brown  silt  loam  prairie  (1126)  of  the  early  Wisconsin  glaciation. 

The  averages  reported  for  the  gray  silt  loam  on  tight  clay  of  the 
lower  Illinoisan  glaciation  represent  57  different  soil  samples. 
In  2  million  pounds  of  the  surface  soil  the  potassium  (the  most 
constant  constituent)  varied  from  23,120  to  26,440  pounds,  the 
phosphorus  varied  from  700  to  1000  pounds,  and  the  nitrogen 
varied  from  2140  to  3500  pounds;  and  in  every  case  the  surface, 
subsurface,  and  subsoil  were  found  to  be  acid. 

The  data  reported  for  the  brown  silt  loam  of  the  early  Wisconsin 
glaciation  are  averages  obtained  by  analyzing  90  different  samples 
of  soil  collected  in  ten  different  counties,  and  representing  more 
than  500  different  borings.  In  2  million  pounds  of  the  surface  soil 
of  this  type  the  potassium  varied  from  31, 980  to  43,100  pounds,  the 
phosphorus  varied  from  980  to  1620  pounds  (or,  if  we  disregard 
four  samples,  from  1020  to  1340  pounds),  and  the  nitrogen  varied 
from  3980  to  7520  pounds  (or  from  3980  to  6340,  if  we  disregard 
two  samples). 

The  limestone  has  not  been  leached  out  of  the  early  Wisconsin 
brown  silt  loam  to  such  a  depth  as  in  the  older  gray  silt  loam.  In 
one  case  limestone  was  present  in  the  surface  of  the  brown  silt 
loam,  and  in  three  cases  it  was  found  in  the  subsurface,  while  it 
was  more  often  present  in  the  subsoil,  although  in  many  cases  even 
the  subsoil  was  found  to  be  acid,  but  never  to  such  a  degree  as  is 
common  for  the  subsoils  of  the  older  brown  silt  loams  (middle  and 
upper  Illinoisan,  pre-Iowan,  and  lowan). 

With  unimportant  exceptions,  all  samples  of  surface,  subsur- 
face, and  subsoil  of  the  yellow  silt  loams  (and  the  yellow  fine  sandy 
loam)  of  the  hill  lands  were  distinctly  acid,  the  degree  varying  with 
the  age  of  the  soil. 

In  the  late  Wisconsin  glaciation  both  the  brown  silt  loam  and 
the  yellow-gray  silt  loam  samples  were  almost  invariably  slightly 
acid  in  the  surface  and  subsurface,  but  exceedingly  well  supplied 
with  carbonates  in  the  subsoil. 


82 


SCIENCE   AND   SOIL 


TABLE  15.   FERTILITY  IN  ILLINOIS  SOILS 
Average  Pounds  per  Acre  in  2  Million  Pounds  of  Surface  Soil  (o-6f  Inches)  l 


SOIL 
TYPE 

NO. 

Son,  AREA  OR 
GLACIATION 

SOIL  TYPE 

TOTAL 
NITRO- 
GEN 

TOTAL 
PHOS- 
PHOR- 
US 

TOTAL 
POTAS- 
SIUM 

LIME- 
STONE 
PRESENT 

LIME- 
STONE 
RE- 
QUIRED 

PRAIRIE  LANDS,  UNDULATING 


33° 

Lower  Illinoisan 

Gray  silt  loam  on 
tight  clay 

2880 

840 

24940 

1160 

426 

Middle  Illinoisan 

Brown  silt  loam 

437° 

1170 

32240 

70 

526 

Upper  Illinoisan 

Brown  silt  loam 

4840 

1200 

32940 

70 

626 

Pre-Iowan  .     . 

Brown  silt  loam 

4290 

1190 

35340 

no 

726 

lowan     .     .     . 

Brown  silt  loam 

4910 

I22O 

32960 

90 

1126 

Early  Wisconsin 

Brown  silt  loam 

505° 

II9O 

36250 

60 

1026 

Late  Wisconsin 

Brown  silt  loam 

6750 

1410 

45020 

60 

PRAIRIE  LANDS,  FLAT 


329 

Lower  Illinoisan 

Drab  silt  loam 

2800 

710 

26260 

1300 

420 
520 

II2O 
I22O 

Middle  Illinoisan 
Upper  Illinoisan 
Early  Wisconsin 
Late  Wisconsin 

Black  clay  loam 
Black  clay  loam 
Black  clay  loam 
Black  clay  loam 

6760 
7840 
8900 

143° 
1690 
2030 
1870 

31860 
29770 

37370 

830 

30 
32530 
980 

TIMBER  UPLANDS,  ROLLING  OR  HILLY 


135 

Unglaciated 

Yellow  silt  loam 

1890 

950 

3J45o 

80 

335 

Lower  Illinoisan 

Yellow  silt  loam 

2150 

950 

31850 

310 

435 

Middle  Illinoisan 

Yellow  silt  loam 

1870 

820 

33470 

40 

535 

Upper  Illinoisan 

Yellow  silt  loam 

2OIO 

840 

34860 

130 

635 

Pre-Iowan   .     . 

Yellow  silt  loam 

2390 

850 

37180 

30 

735 

lowan     .     .     . 

Yellow  silt  loam 

1910 

910 

3578o 

30 

H35 

Early  Wisconsin 

Yellow  silt  loam 

1890 

870 

32720 

60 

864 

Deep  loess  .     . 

Yellow  fine  sandy 

loam    .     .     . 

2I7O 

960 

35640 

70 

1  The  numbers  given  in  Table  15  represent  the  total  amount  contained  in  2 
million  pounds  of  the  surface  soil  on  the  dry  basis,  with  the  exception  of  deep  peat 
swamp  soil,  for  which  the  amounts  in  i  million  pounds  are  used,  because  its  spe- 
cific gravity  is  only  one  half  that  of  ordinary  soil,  and  of  sand  soil  for  which  2 \  million 
pounds  are  used,  because  it  is  about  one  fourth  heavier  than  ordinary  soil. 


SOIL   COMPOSITION 


TABLE  15.    FERTILITY  IN  ILLINOIS  SOILS  —  Continued 


SOIL 
TYPE 

NO. 

SOIL  AREA  OR 
GLACIATION 

SOIL  TYPE 

TOTAL 
NITRO- 
GEN 

TOTAL 
PHOS- 
PHOR- 
US 

TOTAL 
POTAS- 
SIUM 

LIME- 
STONE 
PRESENT 

LIME- 
STONE 
RE- 
QUIRED 

TIMBER  UPLANDS,  UNDULATING 


1034 

Late  Wisconsin 

Yellow-gray    silt 

+ 

loam     .     .     . 

2890 

810 

47600 

40 

760 

lowan     .     .     . 

Brown  sandy  loam 

3070 

850 

26700 

IOO 

TIMBER  UPLANDS,  FLAT 


332 

Lower  Illinoisan 

Light    gray    silt 

loam  on   tight 

clay     .     .     . 

1890 

810 

27280 

45° 

SAND,  SWAMP,  AND  BOTTOM  LANDS 


J331 

Old  bottom  lands 

Deep    gray    silt 

loam    .     .     . 

3620 

1420 

36360 

440 

i45i 

Late  bottom  lands 

Brown  loam 

4720 

1620 

3997° 

2090 

1481 

Sand  plains  and 

dunes  .     .     . 

Sand  soil      .     . 

1440 

820 

30880 

200 

1401 

Late  swamp     . 

Deep  peat   .     . 

34880 

1960 

2930 

X3° 

1415 

Late  swamp     . 

Drab  clay    .     . 

5760 

1900 

48080 

36300 

1400 

Late  swamp     . 

Marly  peat  .     . 

20900 

1520 

920 

1278000 

A  careful  study  of  the  mass  of  evidence  recorded  in  Tables  15, 
16,  and  17  clearly  reveals  the  fact  that  the  most  important  and  most 
extensive  areas  of  Illinois  soils  are  poor  in  phosphorus.  The  only 
soils  well  supplied  with  phosphorus  are  the  black  clay  loams,  the 
bottom  lands,  and  the  clay  and  peaty  swamp  soils.  On  the  other 
hand,  the  supply  of  total  potassium  is  very  great  in  all  of  the  soils 
reported  upon,  with  the  exception  of  the  deep  peat  and  the  abnor- 
mal marly  peat,  which  are  markedly  deficient  in  that  element. 

It  should  be  kept  in  mind  that  small  bodies  of  peat  soil  surrounded 
by  normal  upland  soils  rich  in  potassium  are  likely  to  have  received 
deposits  of  silt  or  clay  by  overflow  from  time  to  time,  and  as  a  rule 
they  are  not  deficient  in  potassium,  and  shallow  peat  bogs  with  clay 


84 


TABLE  16.   FERTILITY  IN  ILLINOIS  SOILS 
Average  Pounds  per  Acre  in  4  Million  Pounds  of  Subsurface  Soil  (6^-20  inches) 


Son. 
TYPE 
No. 

SOIL  AREA  OR 
GLACIATION 

SOIL  TYPE 

TOTAL 
NITRO- 
GEN 

TOTAL 
PHOS- 
PHOR- 
US 

TOTAL 
POTAS- 
SIUM 

LIME- 
STONE 
PRESENT 

LIME- 
STONE 
RE- 
QUIRED 

PRAIRIE  LANDS,  UNDULATING 


330 

Lower  Illinoisan 

Gray  silt  loam  on 

tight  clay 

3210 

1500 

5357° 

635° 

426 

Middle  Illinoisan 

Brown  silt  loam 

5800 

1920 

62590 

no 

526 

Upper  Illinoisan 

Brown  silt  loam 

6480 

2090 

64820 

1  20 

626 

Pre-Iowan      .     . 

Brown  silt  loam 

4650 

2O6O 

72370 

57° 

726 

lowan        .     .     . 

Brown  silt  loam 

5*40 

1940 

66220 

360 

1126 

Early  Wisconsin 

Brown  silt  loam 

6560 

2OOO 

72780 

90 

1026 

Late  Wisconsin  . 

Brown  silt  loam 

6870 

1960 

96420 

15° 

PRAIRIE  LANDS,  FLAT 

329 

Lower  Illinoisan 

Drab  silt  loam 

3160 

1230 

54420 

3980 

420 

Middle  Illinoisan 

Black  clay  loam 

6180 

2260 

64070 

2940 

520 

Upper  Illinoisan 

Black  clay  loam 

738o 

2690 

60760 

70 

II2O 

Early  Wisconsin 

Black  clay  loam 

7200 

3090 

71670 

49300 

1220 

Late  Wisconsin  . 

Black  clay  loam 

9100 

2860 

78840 

1310 

TIMBER  UPLANDS,  ROLLING  OR  HILLY 

135 

Unglaciated   .     . 

Yellow  silt  loam 

2030 

2120 

67320 

4850 

335 

Lower  Illinoisan 

Yellow  silt  loam 

2170 

2000 

67380 

6630 

435 

Middle  Illinoisan 

Yellow  silt  loam 

1980 

ISIO 

65370 

37° 

535 

Upper  Illinoisan 

Yellow  silt  loam 

1900 

1610 

72570 

222O 

635 

Pre-Iowan      .     . 

Yellow  silt  loam 

2290 

i75o 

76150 

650 

735 

lowan  .... 

Yellow  silt  loam 

2I2O 

1960 

71180 

1500 

"35 

Early  Wisconsin 

Yellow  silt  loam 

1870 

159° 

68600 

3910 

TIMBER  LANDS,  UNDULATING 


1034 

Late  Wisconsin  . 

Yellow-gray  silt 

loam      .     .     . 

2710 

1390 

IIIIOO 

34° 

760 

lowan  .... 

Brown     sandy 

loam       .     .     . 

3920 

1590 

543°° 

620 

SOIL  COMPOSITION 


TABLE  16.   FERTILITY  IN  ILLINOIS  SOILS  —  Continued 


Sou, 
TYPE 
No. 

Son.  AREA  OR 
GLACIATION 

Son,  TYPE 

TOTAL 

NITRO- 
GEN 

TOTAL 
PHOS- 
PHOR- 
US 

TOTAL 
POTAS- 
SIUM 

LIME- 
STONE 
PRESENT 

LIME- 
STONE 
RE- 
QUIRED 

TIMBER  UPLANDS,  FLAT 


332 

Lower  Illinoisan 

Light    gray    silt 

loam  on  tight 

clay  .... 

1920 

1240 

58480 

7200 

SAND,  SWAMP,  AND  BOTTOM  LANDS 


I,w 

Old  bottom  lands 

Deep    gray    silt 

loam 

2250 

1830 

68090 

449° 

1451 

Late  bottom  lands 

Brown  loam  .     . 

6660 

2160 

77540 

980 

1481 

Sand  plains  and 

dunes     .     .     . 

Sand  soil  .     .     . 

2070 

1480 

62690 

50 

1401 

Late  swamp  .     . 

Deep  peat      .     . 

64980 

2940 

7010 

2IO 

subsoils  are  also  well  supplied  with  potassium,  or  may  be  by  deep 
plowing;  whereas  broad  areas  of  deep  peat  or  of  shallow  or  medium 
peat  on  sand  are  as  a  rule  deficient  in  potassium. 

Most  of  the  older  soils  (chiefly  in  southern  and  western  Illinois) 
are  markedly  acid  in  the  surface  and  subsurface,  and  exceedingly 
acid  in  the  subsoil.  The  rolling  or  hilly  timber  uplands  and  the 
sand  soil  are  very  deficient  in  nitrogen,  while  the  undulating  prairie 
lands  (except  in  the  late  Wisconsin  glaciation),  the  undulating 
timber  lands,  and  even  the  flat  prairie  lands  in  the  oldest  forma- 
tion, are  only  moderately  well  supplied  with  nitrogen.  The  black 
clay  loams  (especially  in  the  more  recent  formations)  are  rich,  and 
the  peaty  soils  exceedingly  rich,  in  humus  and  nitrogen. 

In  the  main  the  soils  of  central  and  northern  Illinois  are  com- 
parable with  similar  soil  types  in  Indiana  and  Ohio  on  the  east, 
and  with  Iowa  and  eastern  Nebraska  soils  on  the  west;  and  the 
soils  of  southern  Illinois  are  comparable  with  similar  types  in 
Missouri  and  eastern  Kansas  on  the  west,  and  also  with  the  loess- 
covered  areas  in  southern  Indiana,  Kentucky,  Tennessee,  and 
northwest  Mississippi;  while  some  of  the  same  soil  types  that  are 


86 


SCIENCE  AND    SOIL 


TABLE  17.  FERTILITY  IN  ILLINOIS  SOILS 
Average  Pounds  per  Acre  in  6  Million  Pounds  of  Subsoil  (20-40  Inches) 


SOIL 
TYPE 
No. 

SOIL  AREA  OR 
GLACIATION 

Son.  TYPE 

TOTAL 
NITRO- 
GEN 

TOTAL 
PHOS- 

PHOR- 

TOTAL 
POTAS- 
SIUM 

LIME- 
STONE 
PRESENT 

LIME- 
STONE 
RE- 

PRAIRIE  LANDS,  UNDULATING 

33<» 

Lower  Illinoisan 

Gray  silt  loam  on 

tight  clay     .     . 

3240 

2400 

84300 

21580 

426 

Middle  Illinoisan 

Brown  silt  loam 

344° 

2680 

90040 

2OO 

526 

Upper  Illinoisan 

Brown  silt  loam 

3440 

2790 

98580 

460 

626 

Pre-Iowan      .     . 

Brown  silt  loam 

394° 

33«o 

102620 

1650 

726 

lowan  .... 

Brown  silt  loam 

3540 

2780 

99780 

1940 

1126 

Early  Wisconsin 

Brown  silt  loam 

34.20 

2620 

117880 

66600 

1026 

Late  Wisconsin 

Brown  silt  loam 

363° 

2630 

160140 

728000 

329 

Lower  Illinoisan 

Drab  silt  loam 

3400 

1690 

80830 

15770 

42O 
520 
II2O 
1220 

Middle  Illinoisan 
Upper  Illinoisan 
Early  Wisconsin 
Late  Wisconsin 

Black  clay  loam 
Black  clay  loam 
Black  clay  loam 
Black  clay  loam 

3020 

3I4° 
349° 
3180 

303° 
3640 

363° 
393° 

94900 
96220 
111280 
125370 

149200 

I2IO 
II7500 
5470 

TIMBER  LANDS,  ROLLING  OR  HILLY 


135 

Unglaciated  .     . 

Yellow  silt  loam 

1970 

3280 

10543° 

20660 

335 

Lower  Illinoisan 

Yellow  silt  loam 

2480 

317° 

99670 

21500 

435 

Middle  Illinoisan 

Yellow  silt  loam 

2820 

2810 

99000 

3700 

535 

Upper  Illinoisan 

Yellow  silt  loam 

2280 

3270 

100950 

62IO 

635 

Pre-Iowan      .     . 

Yellow  silt  loam 

2380 

3400 

I02IOO 

5480 

735 

lowan  .... 

Yellow  silt  loam 

2490 

3900 

105030 

3750 

H35 

Early  Wisconsin 

Yellow  silt  loam 

2450 

2660 

103830 

44OO 

864 

Deep  loess     .     . 

Yellow  fine  sandy 

loam   .... 

2730 

3320 

IO52IO 

3620 

TIMBER  UPLANDS,  UNDULATING 


1034 

Late  Wisconsin 

Yellow    gray  silt 

loam   .... 

3240 

2400 

156740 

1034000 

760 

lowan  .... 

Brown          sandy 

loam   .... 

4160 

2440 

81180 

49700 

SOIL   COMPOSITION 


TABLE  17.    FERTILITY  IN  ILLINOIS  SOILS  —  Continued 


Son. 
TYPE 
No. 

SOIL  AREA  OR 
GLACIATION 

SOIL  TYPE 

TOTAL 

NITRO- 
GEN 

TOTAL 
PHOS- 
PHOR- 
US 

TOTAL 
POTAS- 
SIUM 

LIME- 
STONE 
PRESENT 

LIME- 
STONE 
RE- 
QUIRED 

TIMBER  UPLANDS,  FLAT 


332 

Lower  Illinoisan 

Light  gray  silt  loam 
on  tight  clay  .     . 

2IOO 

2230 

9055° 

19750 

SAND,  SWAMP,  AND  BOTTOM  LANDS 


I331 

Old  bottom  lands 

Deep    gray     silt 

loam   .... 

2280 

2620 

101610 

9060 

i45i 

Late  bottom  lands 

Brown  loam    .     . 

4150 

2410 

119520 

4620 

1481 

Sand  plains  and 

dunes     .     .     . 

Sand  soil     .     .     . 

3100 

2230 

94030 

80 

1401 

Late  swamp  .     . 

Deep  peat  .     .     . 

9773° 

3740 

11510 

290 

found  in  the  "Great  American  Bottoms"  in  southwestern  Illinois, 
are  found  in  the  Mississippi  Delta  farther  south. 

The  terminal  moraine  of  the  Wisconsin  glaciation  extends  from 
southern  Edgar  County,  Illinois,  to  the  center  of  Parke  County, 
Indiana,  thence  in  a  southeast  direction  to  the  north  line  of  Jen- 
nings County,  thence  northeast  to  the  south  line  of  Fayette  County, 
and  thence  to  the  southeast  corner  of  Franklin  County. 

About  two  thirds  of  the  state  lies  north  of  this  line  and  resembles 
the  timber  uplands  of  northeastern  Illinois,  with  a  smaller  propor- 
tion of  prairie  lands  and  considerable  areas  of  swamp,  especially' 
in  the  Kankakee  river  basin. 

South  of  the  terminal  moraine  the  state  is  largely  loess  covered, 
and  resembles  the  timber  lands  of  southern  Illinois,  except  for  a 
central  area  of  residual  soils  in  Monroe,  Lawrence,  Martin,  Orange, 
Washington,  Warrick,  DuBois,  Crawford,  and  parts  of  most 
adjoining  counties. 

In  the  1907  Report  of  the  Indiana  Geological  Survey,  Mr. 
Robert  E.  Lyons  gives  data  from  which  the  following  table  is 
derived : 


88 


SCIENCE   AND    SOIL 


TABLE  18.   COMPOSITION  OF  SOUTHERN  INDIANA  SURFACE  SOILS 
Pounds  per  Acre  in  2  Million  of  Soil  (About  6f  Inches  Deep) 


SOILS 

NUMBER  OF 
ANALYSES 

TOTAL 
NITROGEN 

ACID-SOLUBLE 
PHOSPHORUS 

Limestone  soil  (Residual  rolling)      .     .     . 

5 

3080 

!330 

Limestone  and  shale  soil  (Residual  rolling) 

i 

3660 

4990 

Volusia  silt  loam  (Residual  shale,  rolling) 

i 

2300 

1160 

Miami  silt  loam  (Loessial,  level)      .     .     . 

i 

1160 

134° 

Waverly  silt  loam  (Stream  valleys)  .     .     . 

2 

445° 

2162 

Ohio  river  bottom  land      

I 

1840 

2430 

Aside  from  the  bottom  lands,  these  soils  are  as  a  rule  markedly 
acid.  The  residual  soil  derived  from  limestone  and  shale  is  rich  in 
phosphorus,  and  the  bottom  lands  are  also  well  supplied  with  that 
element.  On  the  other  soils  much  commercial  fertilizer,  chiefly 
bone  meal  and  acid  phosphate,  is  already  being  used.  The  upland 
silt  loams  are  becoming  very  deficient  in  nitrogen  and  organic 
matter.  Two  analyses  of  the  shale  underlying  some  of  the  residual 
soils  show  an  average  potassium  content  of  64,500  pounds  and 
only  3000  pounds  of  total  calcium,  in  2  million  of  shale. 

The  rolling  residual  soil  derived  from  shale  (Volusia  silt  loam) 
and  the  level  or  gently  undulating  loessial  soil  (Miami  silt  loam) 
are  very  acid. 

A  residual  soil  of  sandstone  origin  is  found  in  Martin,  Lawrence, 
and  some  adjoining  counties.  In  his  discussion  of  Indiana  soil 
types,  Mr.  Charles  W.  Shannon  makes  the  following  suggestive 
statement: 

"  Large  amounts  of  planer  dust  from  the  stone  mills  are  being  used  as  a 
lime  application  on  the  various  soils  with  good  results.  The  most  noted  of 
these  experiments  are  in  cases  where  from  1000  to  2000  pounds  per  acre  of 
the  dust  was  applied  to  fields  of  alfalfa  and  clover,  and  as  a  result  much 
better  stands  were  secured  than  in  parts  without  the  lime.  This  is  a  cheap 
source  of  lime  for  those  who  have  access  to  the  mills." 

As  an  average  of  21  analyses  the  Ohio  Experiment  Station 
(Bulletin  150)  finds,  in  2  million  pounds  of  the  surface  soil  on  the 
Station  farm  at  Wooster,  1880  pounds  of  total  nitrogen  and  920 
pounds  of  acid-soluble  phosphorus;  and  Ohio  Circular  No.  79  re- 


ports  data  showing  31,000  pounds  of  total  potassium  in  the  same 
stratum.  The  average  of  161  soils  from  various  parts  of  Ohio 
shows  960  pounds  of  acid-soluble  phosphorus  in  2  million  of  soil. 
As  a  general  average  about  85  per  cent  of  the  phosphorus  in  such 
soils  is  soluble  in  the  acid  used,  so  that  the  total  phosphorus 
probably  amounts  to  about  noo  pounds. 

The  average  composition  of  three  samples  of  surface  soil  from 
the  loess-covered  uplands  at  the  Missouri  Experiment  Station  at 
Columbia,  in  central  Missouri,  shows  2710  pounds  of  total  nitro- 
gen, 690  pounds  of  total  phosphorus,  and  28,500  pounds  of  total 
potassium,  in  2  million  pounds  of  soil  (Schweitzer,  Missouri  Bul- 
letin No.  5) .  These  amounts  correspond  closely  with  the  average 
composition  of  the  most  common  upland  soils  of  southern  Illinois; 
and  the  more  highly  productive  corn  belt  soils  of  north  central  and 
northwest  Missouri  are  more  nearly  comparable  with  the  brown 
silt  loams  and  black  clay  loams  of  the  middle  Illinoisan  glaciation. 

An  analysis  1  of  the  worn  upland  soil  near  St.  Louis,  Missouri, 
shows  1 1 60  pounds  of  nitrogen,  700  pounds  of  total  phosphorus, 
and  35,200  pounds  of  potassium  in  2  million  of  soil.  This  is  about 
the  average  composition  of  the  subsurface  soil  of  the  deep  loess  area 
in  Illinois,  and  indicates  previous  loss  of  surface  soil  by  washing. 

Professor  Keyser  has  kindly  furnished  the  author  with  some 
unpublished  data  concerning  the  soils  of  Nebraska,  showing  that 
the  glacial  silt  loam  of  eastern  Nebraska,  which  has  been  formed 
evidently  from  the  weathering  of  the  till  of  the  Kansan  glaciation, 
contains,  in  2  million  pounds  of  the  surface,  3940  pounds  of  nitro- 
gen, 660  pounds  of  total  phosphorus,  and  23,000  pounds  of  potas- 
sium; while  the  ordinary  loessial  soil  representing  the  most  common 
corn  belt  type  in  the  southeast  part  of  the  state  (and  probably  of 
northeast  Kansas  as  well)  contains  5160  pounds  of  nitrogen,  1060 
of  total  phosphorus,  and  29,000  pounds  of  potassium,  correspond- 
ing very  closely  to  the  brown  silt  loams  in  the  loess-covered  middle 
and  upper  Illinoisan  glaciation.  The  common  silt  loam  of  the  less 
humid  region  of  central  Nebraska  contains  3680  pounds  of  nitrogen, 
1520  of  phosphorus,  and  48,000  of  potassium. 

A  preliminary  general  soil  survey  of  Iowa    (Stevenson,  Iowa 

1  Reported  by  Doctor  R.  O.  Graham,  Bloomington,  Illinois,  as  a  commercial 
analysis. 


90  SCIENCE   AND    SOIL 

Bulletin  82)  shows  five  important  soil  areas  in  Iowa,  which  closely 
resemble  similar  areas  in  Illinois. 

(1)  About  one  tier  of  counties  bordering  the  Mississippi  (with  a 
western  projection  which  includes  most  of  Cedar,  Johnson,  Iowa, 
Poweshiek,  and  Jasper  counties)  is  termed  the  Mississippi  loess 
area,  and  resembles  the  loessial  soil  on  the  Illinois  side. 

(2)  Similarly,  along  the  Missouri  and  Big  Sioux  rivers  the  two 
western  tiers  of  counties  are  chiefly  in  the  Missouri  loess  area. 

(3)  The  Kansan  glaciation  (overlaid  with  shallow  loess  on  the 
less  rolling  lands)  covers  the  southern  third  of  the  remainder  of 
Iowa,  and  this  resembles  closely  the  lower  Illinoisan,  except  that 
the  older  Kansan  is  more  broken  and  has  much  more  exposed 
till  on  the  eroded  hillsides. 

(4)  The  eastern  part  of  the  remainder  of  the  state  is  covered  by 
the  lowan  glaciation,  and  (5)  the  somewhat  larger  western  part 
by  the  Wisconsin  glaciation,  both  of  which  are  also  found  in  Illi- 
nois.   In  both  states  the  lowan  glaciation  is  characterized  by  its 
rolling  topography  and  perfect  surface  drainage,  and  the  Wiscon- 
sin by  its  level  prairies  which  require  much  artificial  drainage  by 
tile  and  open  ditches. 

Eight  analyses  of  lowan  soils,  reported  to  the  author  by  Doctor 
J.  B.  Weems  while  professor  of  agricultural  chemistry  in  the  Iowa 
State  College,  showed  900  pounds  of  acid-soluble  phosphorus  in 
2  million  of  soil,  as  a  general  average.  The  several  soil  types  repre- 
sented varied  considerably,  however,  as  would  be  expected  from 
comparison  with  similar  Illinois  soils,  the  highest  amount  reported 
being  1600  pounds  of  acid-soluble  phosphorus  per  acre  in  a  6f-inch 
stratum,  corresponding  to  1880  pounds  of  total  phosphorus,  if 
85  per  cent  were  acid-soluble.  (This  method  of  estimating  total 
phosphorus  from  the  acid-soluble  phosphorus  is  never  safe  for 
application  to  individual  soil  samples,  but  it  is  approximately  cor- 
rect for  large  averages  of  most  common  soils  of  central  United 
States.)  The  acid-soluble  potassium  (which  varies  from  less  than 
one  sixth  of  the  total  in  old  soils  to  more  than  one  third  of  the  total 
in  more  recent,  less  weathered  soils)  amounted  to  4670  pounds  as  an 
average  of  the  eight  soils  (the  highest  being  7800  pounds)  in  2  mil- 
lion of  surface  soil,  corresponding  probably  to  30,000  to  40,000 
pounds  of  total  potassium.  The  analysis  of  loess  from  Dubuque, 


SOIL   COMPOSITION 


Iowa,  shows  35,600  pounds  of  total  potassium  in  2  million   (see 
Table  n). 

Since  the  above  was  written  the  author  has  secured,  through  the 
kindness  of  Professor  Stevenson,  the  unpublished  data  shown  in 
Table  18.1  which  present  the  average  results  of  from  one  to  six 
analyses  of  the  most  important  soil  types  in  the  great  soil  areas  of 
the  state.  Professor  Stevenson  writes:  "  The  samples  are  believed 
to  represent  the  most  widely  distributed  type  of  the  respective 
areas.  We  did  not  determine  total  potassium."  (Two  types,  the 
uncovered  glacial  till,  and  the  shallow  loess,  are  included  for  the 
Kansan  area.) 

TABLE  18.1.   PLANT  FOOD  IN  SURFACE  SOILS  OF  IOWA 
Pounds  per  Acre  in  2  Million  (about  6f -inch  Stratum) 


FORMATION  OR  SOIL  AREA 

NUMBER  OF 
ANALYSES 

TOTAL 
NITROGEN 
POUNDS 

TOTAL 
PHOSPHORUS 
POUNDS 

Kansan  glaciation  (exposed  till)    .     .     . 
lowan  glaciation    
Wisconsin  glaciation  

31 
5 
i 

2380 
3940 

7C2O 

860 

1160 
1460 

Loess  on  Kansan  glaciation     .... 
Mississippi  loess     

6 

•2 

3400 

3IOO 

IO2O 
IO2O 

Missouri  loess   

IO 

4.420 

I42O 

1  Only  two  analyses  for  phosphorus  in  the  Kansan  till 

The  Kansan  drift  is  the  oldest  and  the  poorest  in  both  nitrogen 
and  phosphorus,  while  the  Wisconsin  is  the  newest  and  the  richest, 
with  the  lowan  intermediate  in  both  respects.  The  Mississippi 
loess  and  the  shallow  loess  on  the  less  rolling  parts  of  the  Kansan 
glaciation  are  similar  in  composition  and  probably  of  similar  origin 
(of  the  lowan  age) ,  but  the  Mississippi  loess  is  much  deeper  and 
of  a  more  rolling  topography,  which  insures  a  much  better  subsoil, 
physically,  and  may  also  account  for  the  somewhat  lower  nitrogen 
content  of  the  surface,  through  loss  of  organic  matter  by  washing. 
The  higher  phosphorus  content  of  the  Missouri  loess  suggests  that 
it  owes  its  origin  in  part  to  deposits  from  the  semi-arid  plains  of  the 
northwest,  the  richer  mineral  soil  having  encouraged  the  more 
recent  accumulation  of  nitrogen. 


92  SCIENCE  AND    SOIL 


SOILS   OF  THE   SOUTHERN   STATES 

The  average  composition  of  twelve  samples  of  soil  from  seven 
different  counties  in  Kentucky  outside  of  the  Blue  Grass  Region 
shows  550  pounds  of  acid-soluble  phosphorus  in  2  million  pounds 
of  surface  soil;  and  within  the  famous  Blue  Grass  Region  the  supply 
of  acid-soluble  phosphorus  amounts  to  5200  pounds  (nearly  ten 
times  as  much)  in  2  million  of  soil,  as  the  average  of  30  soil  analyses, 
collected  from  five  counties,  these  residual  soils  having  been  formed 
in  part  at  least  from  the  weathering  of  phosphatic  limestone. 

The  state  of  Tennessee  may  be  divided  geologically  into  five 
principal  sections: 

(1)  The  great  loess-covered  undulating  upland  area  of  west 
Tennessee,  lying  chiefly  between  the  Mississippi  and  Tennessee 
rivers. 

(2)  The  Central  Basin,  including  most  of  ten  counties  (David- 
son, Trousdale,  Jackson,  Smith,  Wilson,  Williamson,  Rutherford, 
Bedford,  Marshall,  andMaury)  and  parts  of  several  adjoining  coun- 
ties.    The  Central  Basin  includes  much  of  the  great  phosphate 
beds  of  Tennessee.    It  resembles  in  some  respects  the  Blue  Grass 
region  of  Kentucky,  and  by  some  the  Central  Basin  of  Tennessee 
is  claimed  to  be  the  original  home  of  Kentucky  blue  grass. 

(3)  The  Highland  Rim,  surrounding  the  Central  Basin. 

(4)  The  Cumberland  Plateau,  farther  east. 

(5)  The  East  Tennessee  Valley,  lying  between  the  Cumberland 
Plateau  and  the  Unaka  Mountains  on  the  eastern  border  of  the 
state. 

Table  19  shows  the  plant  food  in  representative  soils  of  each  of 
these  great  sections,  the  averages  of  several  soil  analyses  being 
reported  for  the  more  important  areas  (Mooers,  Tennessee  Bulletin 
78). 

The  average  composition  of  the  yellow  silt  loam  soil  on  the  loess- 
covered  Ozark  Hills  of  southern  Illinois  shows  1890  pounds  of 
nitrogen,  950  pounds  of  phosphorus,  and  31,450  pounds  of  potas- 
sium per  acre  in  2  million  pounds  of  surface  soil,  which  is  practi- 
cally the  same  as  for  the  west  Tennessee  soil.  It  may  be  kept  in 
mind,  too,  that  the  north  line  of  west  Tennessee  is  only  35  miles 


SOIL   COMPOSITION 


93 


TABLE  19.   COMPOSITION  OF  SURFACE  SOILS  OF  TENNESSEE 
Average  Pounds  per  Acre  in  2  Million  of  Soil  (about  6f -inch  Stratum) 


SECTION  OR  AREA 

ORIGIN  OF  Son.      . 

NITROGEN 
(Total) 

PHOSPHORUS 
(Total) 

PoTAssnni 
(Total) 

West  Tennessee     .     . 

Loess  deposit     .     .     . 

1890 

890 

3IO2O 

Highland  Rim  .     .     . 

Limestone      .... 

2IOO 

660 

24600 

Central  Basin    .     .     . 

Limestone   and   phos- 

phate      

2350 

2030 

18160 

Cumberland  Plateau  . 

Sandstone      .... 

1700 

380 

7840 

East  Tennessee  Valley 

Limestone  and  dolomite 

2080 

980 

12130 

Bottom  land      .     .     . 

Alluvial     

2620 

1840 

34160 

from  the  southern  point  of  Illinois,  and  that  much  of  the  upland 
soil  of  northwest  Mississippi  is  essentially  of  the  same  character. 

It  will  be  noted  that  the  average  soil  of  the  Central  Basin  is 
comparatively  rich  in  phosphorus,  while  the  soils  of  the  Highland 
Rim,  and  more  especially  the  sandstone  soils  of  the  Cumberland 
Plateau,  are  extremely  deficient  in  phosphorus,  and  the  latter 
is  also  very  poor  in  potassium,  as  might  be  expected  from  its  origin. 

The  number  of  soil  analyses  entering  the  averages  in  Table  19  is 
not  sufficient  for  final  data,  but  in  the  main  they  are  supported  by 
larger  numbers  of  analyses  for  acid-soluble  plant  food.  Thus,  the 
averages  of  25  analyses  of  soils  from  eight  counties  in  the  Central 
Basin  show  2020  pounds  of  acid-soluble  phosphorus  in  2  million 
of  soil,  while  700  pounds  of  phosphorus  is  the  corresponding  aver- 
age for  1 6  analyses  of  loessial  soil  from  eleven  counties  in  west 
Tennessee.  The  acid-soluble  phosphorus  in  the  samples  whose 
total  phosphorus  content  was  determined  (and  thus  afforded  for 
use  in  Table  19)  was  1710  pounds  for  the  Central  Basin  and  750 
pounds  for  the. west  Tennessee  soil,  84  per  cent  of  the  total  having 
been  dissolved  by  strong  hydrochloric  acid,  in  either  case.  On 
this  basis,  the  general  average  of  all  samples  would  show  830 
pounds  of  total  phosphorus  for  west  Tennessee  and  2400  pounds 
for  the  Central  Basin,  in  2  million  pounds  of  surface  soil. 

Hilgard  reports  the  average  of  97  analyses  of  Mississippi  soils 
showing  790  pounds  of  acid-soluble  phosphorus  in  2  million  pounds 
of  surface  soil,  but  the  more  abundant  upland  soils  average  about 


94 


SCIENCE   AND    SOIL 


700  pounds,  while  4100  pounds  of  phosphorus  per  acre  (in  a  6f -inch 
stratum)  have  been  found  in  an  upland  soil  of  limestone  origin. 
The  "  black  prairie  "  limestone  soils  found  in  limited  area  in 
northeastern  Mississippi  and  in  northwestern  Alabama  are  as  a 
rule  well  supplied  with  phosphorus.  This  formation  is  apparently 
an  extension  of  that  found  so  commonly  in  the  broad  Central  Basin 
of  Tennessee,  which  also  extends  into  Kentucky,  where  it  again 
expands  into  the  great  Blue  Grass  Region. 

An  analysis  made  by  Doctor  H.  C.  White  of  a  sample  of  soil 
representing  the  University  farm  of  Georgia,  collected  in  March, 
1884,  from  land  that  "  had  been  cleared  in  December  (1883)  of  a 
second  growth  of  oak  and  hickory,"  gave  the  following  amounts 
per  acre  based  upon  the  surface  foot,  which  was  assumed  to  weigh 
3,528,000  pounds. 

TABLE  19.1.   COMPOSITION  OF  GEORGIA  SOIL  (UNIVERSITY  FARM) 


PLANT-FOOD  ELEMENTS 

POUNDS  PER 
ACRE  FOOT 

POUNDS  IN 
2  MILLION 

Nitrogen    

36<2 

2OOO 

Phosphorus     

"^O 

3OO 

Potassium       

2IOOO 

I2OOO 

Magnesium     

C7OO 

32OO 

Calcium     

74OO 

4IOO 

Iron       

2Q7OO 

l6lOO 

Sulfur                            

IIOO 

6dO 

The  original  statement  reports  "  sand  and  clay,"  and  it  must  be 
assumed  that  the  mineral  elements  as  given  above  represent  the 
amounts  soluble  in  strong  acid. 

The  Texas  Experiment  Station  has  analyzed  a  considerable 
number  of  soil  samples  collected  to  represent  six  general  groups  or 
"  series,"  as  mapped  and  named  by  the  United  States  Bureau  of 
Soils.  The  following  descriptions  are  taken  from  Texas  Bulletin 

99 


"Norfolk  soils.  These  are  light-colored  upland  sandy  soils,  with  a  yellow 
clay  or  sandy  clay  subsoil,  usually  with  good  drainage. 

"  Of  the  areas  under  study,  the  Norfolk  soils  are  found  in  Anderson,  Houston, 
and  Bexar  counties.  They  are  widely  distributed  in  the  eastern  part  of  the 
state. 


SOIL   COMPOSITION 


95 


"Orangeburg  soils.  The  Orangeburg  soils  are  gray  to  brown  upland 
soils,  with  a  red  or  yellowish  clay  sandy  subsoil.  The  red  color  of  the  sub- 
soil distinguishes  the  Orangeburg  soils  from  the  Norfolk  soils.  The  red  soils 
appear  to  be  more  productive,  and  are  generally  stronger  than  the  correspond- 
ing soils  of  the  Norfolk  series.  The  Orangeburg  soils  are  widely  distributed, 
especially  in  East  Texas. 

"Lufkin  soils.  The  Lufkin  soils  are  gray,  with  heavy,  very  impervious 
plastic  gray  and  mottled  subsoils.  These  soils  are  generally  lower  in  agricul- 
tural value  than  the  Norfolk  and  Orangeburg  soils,  perhaps  on  account  of  the 
nature  of  the  subsoils.  These  soils  are  found  in  Houston,  Lamar,  and  Travis 
counties,  of  the  areas  studied. 

"  Susquehanna  series.  These  are  gray  and  brown  surface  soils  with  heavy 
plastic  mottled  subsoils.  They  differ  from  the  Lufkin  series  in  the  color  of  sub- 
soil. They  are  generally  of  low  productiveness. 

"Houston  series.  These  are  black  calcareous  prairie  soils,  very  productive 
and  durable.  They  are  among  the  best  soils  of  the  state.  Some  of  them  have 
been  in  cultivation  forty  or  fifty  years  without  fertilizer,  and  though  some  of 
them  have  decreased  somewhat  in  fertility,  they  are  still  productive.  They 
are  found,  in  areas  surveyed,  in  Lamar,  Hays,  Travis,  and  Bexar  counties. 
They  are  of  general  occurrence  in  the  east-central  portion  of  the  state. 

"These  soils  appear  to  owe  their  productiveness  to  their  content  of  lime  and 
organic  matter,  and  nitrogen.  Some  of  these  soils  will  become  deficient  in 
phosphoric  acid. 

"  Yazoo  soils.  These  soils  are  bottom  land,  generally  subject  to  overflow 
and  very  productive.  The  soils  are  mapped  in  only  two  areas,  Anderson  and 
Travis  counties. " 

The  following  tabular  statement  gives  the  average  amounts  of 
total  nitrogen,  acid-soluble  phosphorus,  and  acid-soluble  potassium 
in  2  million  pounds  of  the  surface  soil  of  these  different  soil  types, 
based  upon  the  analyses  reported  by  Doctor  Fraps. 

TABLE  19.2.    AVERAGE  COMPOSITION  OF  SOME  TEXAS  SOILS 
Pounds  in  2  Million  of  Soil 


CONVENTIONAL  NAME 

Son.  TYPE 

TOTAL 
NITRO- 
GEN 

ACID- 
SOLUBLE 
PHOS- 
PHORUS 

ACID- 
SOLUBLE 
POTAS- 
SIUM 

Norfolk  soils     .     . 
Orangeburg  soils  . 
Lufkin  soils 
Susquehanna  series 
Houston  series 

Light  sandy  upland     .... 
Gray  -brown  sandy  upland 
Gray  silt  loam  on  tight  clay    .     . 
Gray-brown  silt  loam  on  tight  clay 
Black  prairie       

1000 
1200 
1000 

1400 
2800 

180 

440 

180 

260 

C30 

2OOO 
620O 
1800 
3700 
5600 

Yazoo  soils  . 

Bottom  land  

1600 

060 

6700 

96 


SCIENCE   AND   SOIL 


With  the  exception  of  the  bottom  land,  these  soils  are  extremely 
poor  in  phosphorus;  and,  aside  from  the  black  prairie,  they  are 
also  very  poor  in  nitrogen. 

Hilgard  reports  940  pounds  of  acid-soluble  phosphorus  in  2 
million  pounds  of  Louisiana  soil,  as  an  average  of  35  analyses. 
The  Geological  Survey  of  Louisiana  has  furnished  the  data  for 
the  following  statement,  showing  the  total  nitrogen,  acid-soluble 
phosphorus,  and  acid-soluble  potassium  in  8  surface  soils  and  2 
subsoils  in  Madison  Parish,  opposite  Vicksburg.  These  are  all 
alluvial  soils  deposited  from  the  overflow  of  the  Mississippi  River. 

TABLE   19.3.   COMPOSITION   OF   LOUISIANA   SOILS  IN   MADISON   PARISH 
Pounds  in  2  Million  of  Soil 


DESCRIPTION  OF  SOIL 

TOTAL 
NITROGEN 

ACID-SOLUBLE 

Phosphorus 

Potassium 

Black  soil  on  buckshot  clay;  virgin  swamp, 
but  good  land  when  cleared  
Subsoil  of  same  type    

3986 
1286 

1450 
1044 

6562 
4976 

Dark  gray  soil  on  buckshot  clay;  once  swamp; 
cultivated  9  years    
Subsoil  of  same      

3334 
95° 

1174 
928 

5466 
3570 

Dark  gray  clay;  virgin  soil  ;  wooded  swamp; 
overflow  land      
Black  waxy  soil  on  dark  gray  clay;  very  fer- 
tile when   thoroughly  drained;    i£  to  2 
bales  of  cotton  per  acre     

2286 

2456 
2662 
1562 
1244 

1306 

2OOO 

2O24 
1760 
1234 
1474 

I2O6 

8412 

5134 
4748 
5084 
4IOO 

3806 

Black  soil  on  buckshot  clay  
Brown  silty  loam  ;  old  land 

Brown  sandy  loam  ;  cultivated  50  years  .     . 
Light  brown  sandy  loam;  once  productive, 
but  now  worn  out  for  corn  and  cotton 

In  phosphorus  content  these  soils  resemble  the  late  bottom  lands 
of  Illinois,  but  the  nitrogen  content  is,  as  a  rule,  much  lower  in  the 
Louisiana  soils,  and  extremely  low  in  the  old,  worn  soils. 

It  may  be  mentioned  here  that  the  Mississippi  Experiment 
Station  has  conducted  some  field  experiments  on  delta  lands, 
concerning  which  the  following  is  reported  in  Mississippi  Bulletin 
119: 


SOIL   COMPOSITION 


97 


"The  land  on  which  the  tests  were  made  had  been  cropped  in  cotton  for 
many  years.  A  part  of  it  is  loam  soil  and  is  well  drained.  A  test  was  also 
made  on  stiff  buckshot  land." 

"The  average  increase  from  300  pounds  of  high  grade  cotton  seed  meal 
per  acre  for  the  three  years  (1906-8)  has  been  106  pounds  of  lint  cotton. 
We  have  not  been  able  to  increase  the  size  of  the  crop  nor  its  earliness  by 
the  use  of  either  phosphorus  or  potash." 

"The  increase  from  the  application  of  300  pounds  of  cotton  seed  meal  to 
the  stiff  buckshot  land  was  36  pounds  of  lint  cotton  per  acre.  This  is  not 
sufficient  to  make  the  use  of  the  meal  profitable  on  this  character  of  land." 

As  an  average  of  38  analyses  of  Arkansas  soils,  Hilgard  gives 
1400  pounds  of  acid-soluble  phosphorus  in  2  million  of  soil,  sug- 
gesting bottom-land  soils  or  some  connection  with  the  phosphate 
deposits  of  that  state. 


SOILS   OF   THE   NORTHERN   STATES 

In  the  northern  tier  of  states,  where  the  soils  are  of  more  recent 
origin  and  where  the  climate  of  winter  offers  less  exposure  to  weath- 
ering and  leaching,  the  normal  soils  are,  as  a  rule,  richer  in  mineral 
plant  food,  as  is  indicated,  for  example,  by  comparing  the  soils  of 
the  late  Wisconsin  glaciation  in  northern  Illinois  with  similar 
types  in  the  older  middle  Illinoisan  glaciation.  Of  course,  the  up- 
land timber  soils  are  not  comparable  in  nitrogen  content  with  the 
black  prairie  soils. 

The  late  Doctor  Robert  C.  Kedsie,  one  of  the  few  great  scientists 
who,  with  Doctor  E.  W.  Hilgard  and  Doctor  S.  W.  Johnson,  helped 
to  lay  firm  foundations  for  the  American  Agricultural  Experiment 
Stations,  reported  analyses  of  28  Michigan  soils  grouped  in  accord- 
ance with  a  general  survey  or  classification  of  the  soils  of  that 
state  (Michigan  Bulletin  99) : 

1.  The  four  southern  tiers  of  counties  are  classed  as  theMichigan 
"wheat  belt." 

2.  The  area  along  the  eastern  shore  of  Lake  Michigan,  including 
especially  the  light  porous  soils  upon  which  peaches  of  the  finest 
quality  are  extensively  produced,  is  termed  the  "  peach  belt." 

3.  Several  counties  in  the  Traverse  Bay  region,  including  much 
soil  of  the  sandy-loam  type,  constitute  the  "  potato  district." 


98 


SCIENCE  AND    SOIL 


4.  The  large  tract  of  light,  sandy  lands  in  the  north-central  part 
of  the  Lower  Peninsula  is  called  the  "  Jack  Pine  Plains." 

5.  The  peaty  swamp  soils,  used  especially  for  the  growing  of 
celery,  peppermint,  etc.,  are  so  designated. 

In  Table  20  is  given  the  average  composition  of  the  soils  from 
each  of  these  sections.  The  nitrogen  reported  is  total,  but  the  data 
for  phosphorus  and  potassium  represent  only  the  amount  soluble 
in  acids,  probably  much  stronger,  however,  than  now  commonly 
used.  The  amount  closely  approaches  the  total  in  case  of  phos- 
phorus, but  probably  represents  less  than  one  half  of  the  total 
potassium  actually  present  in  the  soil.  (A  larger  proportion  of  the 
total  potassium  present  in  the  newer,  less-weathered  soils  is  soluble 
in  acid  than  of  the  total  potassium  in  the  older  leached  soils  found 
in  the  states  farther  south.) 

TABLE  20.  AVERAGE  COMPOSITION  or  SOME  MICHIGAN  SOILS 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6§  Inches) 


ACID- 

ACID- 

AREA 

Son,  SECTION 

SOLUBLE 

SOLUBLE 

PHOSPHORUS 

POTASSIUM 

(i)  Southern  Michigan 

Wheat  belt    .     . 

4600 

3600 

27360 

(2)  Lake  shore  region    .     . 

Peach  belt     .     . 

1860 

2330 

22600 

(3)  Traverse  Bay  region     . 

Potato  district    . 

1260 

1520 

16400 

(4)  North-central  tract  .     . 

Jack  Pine  Plains 

740 

290 

4600 

(5)  Swamp  areas  .... 

Deep  peat  ]    . 

22OOO 

2980 

2660 

1  The  amounts  given  for  deep  peat  represent  the  plant  food  in  i  million  pounds 
of  the  material,  the  specific  gravity  of  which  is  about  one  half  that  of  ordinary  soils. 

These  striking  and  valuable  results  obtained  in  a  very  prelimi- 
nary general  survey  of  Michigan  soils  clearly  indicate  the  much 
greater  possible  value  of  an  extended  and  detailed  investigation  of 
the  soils  of  the  state.  The  high  phosphorus  content  of  theMichigan 
soils,  especially  of  the  great  area  of  the  wheat  belt  (3600  pounds), 
is  in  marked  contrast,  not  only  with  the  extremely  low  phosphorus 
content  of  the  Jack  Pine  Plains  (290  pounds,  —  less  than  one 
tenth  as  much),  but  also  with  the  small  supply  of  phosphorus  in 
the  common  upland  soils  of  southern  Illinois,  central  Missouri, 
and  the  western  parts  of  Kentucky,  Tennessee,  and  other  southern 
states. 


SOIL   COMPOSITION 


99 


In  commenting  on  his  study  of  Michigan  soils,  Doctor  Kedsie 
said: 

"  Chemical  analysis  of  the  soil  is  of  value  in  determining  whether  the  soil  is 
capable  of  fertility  or  the  contrary ;  also  in  determining  the  measure  of  its 
possible  fertility.1  There  are  certain  ash  elements  which  are  absolutely  nec- 
essary for  plant  growth,  in  the  absence  of  any  one  of  which  vegetable  growth 
is  impossible;  if  the  supply  is  relatively  limited,  plant  growth  will  be  limited 
correspondingly.  Hence,  chemical  analysis  of  a  soil  is  of  importance  in  deter- 
mining possibility  of  fertility  and  of  the  relative  fertility  which  may  be  secured 
under  favorable  conditions.  .  .  .  Chemical  analysis  will  not  always  dis- 
tinguish between  a  fruitful  and  an  unfruitful  soil.  A  soil  may  be  unproductive 
for  physical  reasons,  though  it  may  still  contain  all  the  chemical  elements  of 
fertility. " 

The  Michigan  wheat-belt  soils  include  several  different  soil  types, 
but  among  the  nine  soil  samples  analyzed  from  that  area,  the  poor- 
est contained  260x3  pounds  of  acid-soluble  phosphorus,  or  500  pounds 
more  than  the  average  of  the  best  Illinois  soil.  More  than  four 
times  as  much  phosphorus  is  contained  in  the  average  Michigan 
wheat-belt  soil  (when  these  samples  were  taken)  as  is  now  con- 
tained in  the  common  soils  of  southern  Illinois. 

A  preliminary  general  survey  of  Wisconsin  soils  (Whitson, 
Wisconsin  Agricultural  Experiment  Station,  Annual  Report  for 
1905,  pages  262-270)  outlines  seven  different  great  soil  areas  in 
that  state : 

(i)  The  unglaciated  area  of  the  southwest  quarter  (extending 
into  northwestern  Illinois)  with  three  subdivisions  in  which  residual 
sands,  sandy  loams,  and  clay  loams,  respectively,  predominate; 
(2)  the  early,  and  (3)  the  late  glaciations  (each  in  two  divisions  based 
upon  the  underlying  rocks),  occupying  largely  the  remaining 
three  fourths  of  the  state,  and  covered  with  glacial  till,  with  little 
or  no  loess  deposit;  (4)  separated  sand  areas  of  glacial  origin,  as 
in  the  south-central,  extreme  northern,  and  northwest  parts  of  the 
state;  (5)  a  loessial  area  covering  a  strip  of  upland  along  the 
Mississippi;  (6)  "red  clay"  areas  of  lacustrine  origin  between 
Green  Bay  and  Lake  Winnebago  and  on  the  Lake  Superior  shore; 
and  (7)  the  scattered  swamps  of  muck  and  peat. 

But  few  analyses  of  Wisconsin  soils  have  been  reported.   An 

1  Italics  by  C.  G.  H. 


ioo  SCIENCE   AND   SOIL 

ultimate  analysis  of  'virgin  soil  from  the  Wisconsin  Experiment 
Station  Farm  at  Madison,  in  the  late  glaciation,  shows  3600  pounds 
of  nitrogen,  1500  pounds  of  phosphorus,  and  36,300  pounds  of 
potassium,  in  2  million  pounds  of  surface  soil.  Where  the  same  soil 
had  been  heavily  cropped  in  pot  cultures  (19  crops  having  been 
removed)  the  nitrogen  was  reduced  to  2200  pounds  and  the  phos- 
phorus to  1140  pounds,  with  no  determinable  change  in  total 
potassium  content.  The  analysis  of  another  soil  from  the  late 
glaciation  from  northern  Outagamie  County  showed  1400  pounds 
of  nitrogen  and  2380  pounds  of  acid-soluble  phosphorus.  This 
glaciation  Professor  Whitson  regards  as  the  best  soil  area  in  the 
state. 

Residual  sand  from  Jackson  County  contained  1000  pounds  of 
nitrogen,  870  of  phosphorus,  and  5100  of  total  potassium  in  2 
million  of  surface  soil,  and  the  glacial  sand  from  Vilas  County  con- 
tained 1000  pounds  of  nitrogen,  1580  pounds  of  phosphorus,  and 
30,000  pounds  of  potassium,  indicating  that  the  residual  sand  is 
more  largely  quartz,  while  the  glacial  sand  consists  chiefly  of  sili- 
cate minerals.  (Compare  with  Tennessee  soils.) 

Red  clay  from  Ashland  County  contained  1400  pounds  of  acid- 
soluble  phosphorus  in  2  million  of  soil;  and  peaty  swamp  soil  from 
Sauk  County  contained  32,000  of  nitrogen,  1230  pounds  of  acid- 
soluble  phosphorus,  and  only  910  pounds  of  acid-soluble  potassium, 
in  i  million  pounds  of  the  surface  soil. 

The  acid-soluble  plant  food  has  been  determined  in  many  Minne- 
sota soils  (Snyder,  Minnesota  Bulletin  41),  and  a  few  analyses  are 
reported  showing  the  total  plant  food  in  representative  soils. 

The  average  prairie  soil  o£  the  Red  River  Valley  in  northwestern 
Minnesota  contains  8200  pounds  of  nitrogen,  3340  pounds  of  phos- 
phorus, and  45,100  pounds  of  potassium  in  the  surface  2  million 
pounds;  and  the  average  prairie  soil  in  west-central  Minnesota 
contains  5300  pounds  of  nitrogen,  1760  pounds  of  phosphorus, 
and  63,300  pounds  of  potassium.  A  general  average  for  the  soils 
of  the  east-central  part  of  the  state  is  5600  pounds  of  nitrogen, 
2460  pounds  of  phosphorus,  and  29,000  pounds  of  total  potassium; 
while  the  average  southeastern  Minnesota  soils  contain  4400 
pounds  of  nitrogen,  1910  pounds  of  phosphorus,  and  30,200  pounds 
of  potassium,  in  2  million  pounds  of  surface. 


SOIL   COMPOSITION  101 

From  the  general  glacial  map  of  the  United  States  it  will  be 
seen  that  southeastern  Minnesota  lies  in  the  older  lowan  glaciation, 
while  most  of  the  remainder  of  the  state  is  covered  by  the  late 
Wisconsin  glaciation.  This  may  account  for  the  marked  difference 
in  potassium  content  between  the  soils  of  eastern  and  western 
Minnesota.  (See  also  Tables  15,  16,  and  17  for  a  comparison  of 
these  areas  in  Illinois.)  It  will  be  noted  that  the  Red  River  basin 
lies  within  the  boundaries  of  the  old  glacial  lake,  "  Agassiz."  (See 
also  Canadian  soils.) 

The  analysis  of  a  sample  composed  of  equal  parts  of  two  hundred 
representative  soils  from  various  parts  of  Minnesota  showed  2360 
pounds  of  acid-soluble  phosphorus  in  2  million  of  soil. 

SOILS   OF   THE   WESTERN   STATES 

The  soils  of  the  arid  plains  are,  as  a  rule,  rich  in  mineral  plant  food 
and  poor  in  nitrogen,  doubtless  due  to  the  fact  that  with  but  little 
rainfall  there  has  been  practically  no  loss  of  minerals  by  leaching, 
and  but  small  accumulation  of  vegetable  matter,  in  which  the 
supply  of  nitrogen  is  contained.  Headden  (Colorado  Bulletin  65) 
reports  ultimate  analyses  of  four  Colorado  soils,  showing  as  an  aver- 
age 2900  pounds  of  phosphorus  and  39,50x2  pounds  of  potassium; 
but  the  average  of  six  soils  shows  only  2000  pounds  of  nitrogen, 
in  2  million  of  surface  soil.  Widtsoe  (Utah  Bulletin  52)  shows  37 
analyses  of  Utah  soils  averaging  1850  pounds  of  acid-soluble  phos- 
phorus and  2450  pounds  of  total  nitrogen,  in  2  million  of  soil,  in 
the  most  fertile  valleys.  On  the  arid  plains  the  supply  of  nitrogen 
is  usually  very  much  less.  Doctor  Widtsoe  states  that  he,  "  in 
common  with  those  who  have  traversed  the  wastes  of  western 
America,  has  traveled  for  days  without  seeing  a  trace  of  vegeta- 
tion, and  such  soils  are  almost  devoid  of  organic  matter  and  humus, 
and  contain  but  small  quantities  of  nitrogen."  Hilgard  gives  600 
pounds  of  total  nitrogen  and  2000  pounds  of  acid-soluble  phosphorus 
in  2  million  of  soil,  as  the  average  of  16  analyses  of  the  arid  soils  of 
Colorado.  As  a  rule,  the  soils  of  the  arid  region  contain  about  3 
per  cent  of  lime  (CaCO3),  or  30  tons  of  calcium  carbonate  in  2 
million  pounds  of  soil;  and  the  Utah  Station  reports  18  soil  analyses 
from  one  county,  containing  as  an  average  more  than  20  per  cent 


102  SCIENCE   AND   SOIL 

of  calcium  carbonate  corresponding  to  200  tons  per  acre  to  a  depth 
of  6|  inches. 

For  2  million  pounds  of  surface  soil,  Hilgard's  "  Soils"  gives  the 
following  amounts  of  acid-soluble  phosphorus  as  the  average  of 
many  analyses:  Nevada,  2800;  Wyoming,  1570;  Montana,  1920; 
Idaho,  1400.  Mr.  E.  E.  Hoskins,  while  a  student  in  the  University 
of  Illinois,  analyzed  a  sample  said  to  represent  good  "  bench  " 
land  near  Boise  City,  Idaho,  finding  2350  pounds  of  nitrogen,  1320 
of  total  phosphorus,  and  41,400  pounds  of  potassium,  in  2  million 
of  soil. 

In  the  Pacific  coast  states,  Hilgard  reports  (as  acid-soluble) 
1830  pounds  of  phosphorus  and  10,790  of  potassium  for  Washing- 
ton, 960  of  phosphorus  and  8960  of  potassium  for  Oregon,  in  2 
million  pounds  of  surface  soil;  also  2800  pounds  of  total  nitrogen, 
875  of  acid-soluble  phosphorus,  and  10,100  pounds  of  acid-soluble 
potassium,  in  2  million  pounds  of  the  surface  soils  of  California, 
as  an  average  of  262  analyses. 

THE   SOILS   OF   CANADA 

It  will  be  kept  in  mind,  of  course,  that  Canada  comprises  an 
immense  territory  (3,300,000  square  miles,  compared  with 
3,600,000  square  miles  in  the  United  States,  including  nearly 
600,000  square  miles  in  Alaska)  and  includes  vast  areas  that  are 
uninhabited,  and  in  part  uninhabitable,  although  the  more  favored 
regions  are  sufficiently  extensive  ultimately  to  support  a  mighty 
nation. 

The  Canadian  Agricultural  Experiment  Station  (known  officially 
as  the  Dominion  Experimental  Farms,  with  headquarters  at 
Ottawa)  has  made  analyses  of  Canadian  soils  collected  from  Van- 
couver Island  on  the  west  to  Nova  Scotia  on  the  east.  Perhaps 
the  most  complete  investigation  has  been  made  of  the  valley  lands 
and  Piedmont  soils  of  British  Columbia.  In  general,  these  soil 
investigations  have  been  conducted  with  reference  to  uncultivated 
lands  or  lands  put  under  cultivation  in  recent  years.  They  do  not 
represent  the  comparatively  small  areas  of  Canadian  soil  that  have 
been  long  cultivated,  some  of  which  has  already  been  much  de- 
pleted or  much  fertilized.  The  samples  have  been  collected  with 


EUGENE  WOLDEMAR  HILGARD,  A  MAN  OF  SCIENCE 


Born  at  Zweibriicken,  Bavaria,  January  5, 1833  ;  educated  at  Belleville,  Illinois,  and  Heidel- 
berg, Germany  ;  state  geologist  and  professor  of  chemistry  of  the  University  of  Mississippi, 
1855-1873  ;  professor  of  geology  and  natural  history  of  the  University  of  Michigan,  1873- 

1875; 
statii 


75  ;  professor  of  agriculture  and  director  and  chemist  of  the  agricultural  experiment 
tion,  University  of  California,  1875-1906  ;  chemist  since  1906  ;  author  of  "  Soils  "  (1906) 


SOIL   COMPOSITION 


103 


sufficient  purpose,  method,  and  discrimination  to  give  much  im- 
portance to  the  results,  which  are  summarized  as  follows: 

TABLE  20.1.     COMPOSITION  OF  CANADIAN  SURFACE  SOILS 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6f  Inches) 


ACID-SOLUBLE 

NUMBER  OF 

TOTAL 

ANALYZED 

NITROGEN 

Phosphorus 

Potassium 

Calcium 

21 

British  Columbia  .... 

5240 

2360 

6970 

16700 

6 

Northwest  Territory  .     .     . 

9180 

1520 

5670 

4I30 

I 

Manitoba      

2OIOO 

2f  -JQ 

17100 

27000 

6 

Quebec    

4^2O 

1  7^0 

74OO 

6 

Ontario  (Muscoka  only) 

2700 

1250 

3650 

6300 

5 

Maritime  Provinces    .     .     . 

26OO 

960 

7300 

157° 

In  referring  to  the  averages  represented  in  this  tabular  state- 
ment, Professor  Frank  T.  Shutt  (Chief  Chemist  for  the  Dominion 
Experimental  Farms  since  1887)  says: 

"They  are  not  provincial  averages;  they  are  rather  averages  from  large 
untilled  areas  in  the  several  provinces,  and  may  therefore  serve  to  indicate 
the  general  character  of  much  of  the  yet  unoccupied  lands  of  Canada."  (Do- 
minion Experimental  Farms  Reports,  1897,  page  169.) 

A  study  of  the  details  shows  much  variation,  but  in  the  main 
these  are  counterbalanced  so  that  the  averages  have  much  meaning. 
Professor  Shutt  states  that  the  one  sample  from  Manitoba  "  repre- 
sents the  unfertilized  and  uncropped  prairie  soil  of  the  Red  River 
Valley,  Manitoba,"  and  adds: 

"It  was  taken  from  section  31,  township  4,  range  i  west.  The  uniformity 
in  character  of  the  soil  over  a  very  large  area  in  Manitoba  makes  the  data  here 
presented  of  more  than  ordinary  importance. " 

"We  may  safely  conclude  that  there  is  here  ample  scientific  proof  of  the  well- 
nigh  inexhaustible  stores  of  plant  food,  and  that  this  prairie  land,  as  regards 
the  elements  of  fertility,  ranks  with  the  richest  of  known  soils. " 

Doctor  George  M.  Dawson,  Director  of  the  Geological  Survey  of 
Canada,  is  quoted  as  follows: 

"Of  the  alluvial  prairie  of  the  Red  River  much  has  already  been  said,  and 
the  uniform  fertility  of  its  soil  cannot  be  exaggerated.  .  .  .  The  area  of  this 
lowest  prairie  has  been  approximately  stated  as  6900  square  miles. " 


104  SCIENCE  AND   SOIL 

Of  course,  these  averages  from  the  various  Canadian  provinces 
must  be  considered  as  tentative  and  very  preliminary,  but  they 
must  also  be  accepted  as  giving  a  reasonably  correct  general  view 
of  the  invoice  of  soil  fertility  in  the  most  extensive  types  of  soil 
in  those  sections.  Some  other  analyses  made  in  part  in  connection 
with  special  investigations  are  discussed  in  another  place. 

REVIEW  OF  SOIL  COMPOSITION 

A  general  summary  of  the  mass  of  evidence  contained  in  the 
preceding  pages  concerning  the  composition  of  soils  clearly  sets 
forth  a  number  of  definite  and  assured  facts  bearing  significant  rela- 
tions to  systems  of  permanent  agriculture.  One  of  these  most 
clearly  established  facts  is  that  potassium  as  an  element  of  plant 
food  belongs  in  the  class  with  calcium  and  magnesium  rather  than 
with  phosphorus  and  nitrogen.  In  all  normal  soils  the  supply  of 
potassium  is  enormous.  Thus,  as  an  average  of  the  Maryland  soils 
reported  in  Table  12,  representing  ten  different  geological  forma- 
tions, more  or  less  abundant  in  most  of  the  Atlantic  states,  we  find 
37,860  pounds  of  potassium  and  only  14,080  pounds  of  magnesium, 
7840  pounds  oL  calcium,  and  noo -pounds  of  phosphorus,  in  2 
million  pounds  of  soil. 

Measured  by  the  total  requirements  of  approximately  maximum 
crops  in  a  rotation  of  wheat,  com,  oats,  and  clover  (Table  13),  the 
potassium  is  sufficient  for  473  years,  the  magnesium  for  828  years, 
and  the  calcium  for  187  years;  while  the  total  phosphorus  is  suffi- 
cient for  the  same  crops  for  only  57  years.  If  we  consider  the  plant 
food  removed  in  the  grain  alone,  assuming  that  the  coarse  products 
will  remain  on  the  farm,  and  also  disregard  the  one  abnormal  mag- 
nesium soil  (from  serpentine),  the  relative  plant-food  supply  is 
represented  by  105  years  for  phosphorus,  3060  years  for  potassium, 
2828  years  for  magnesium,  and  6970  years  for  calcium. 

The  complete  analyses  of  the  loess  deposits  at  Dubuque,  Iowa, 
and  Kansas  City,  Missouri,  which  contain  only  moderate  amounts 
of  carbonates,  show,  as  an  average,  33,100  pounds  of  potassium, 
13,400  pounds  of  magnesium,  23,500  pounds  of  calcium,  and  1400 
pounds  of  phosphorus,  in  2  million  of  loess. 

In  the  following  summary  are  reported  the  total  phosphorus, 


SOIL   COMPOSITION 


total  potassium,  total  magnesium,  and  total  calcium  in  the  surface 
soil  of  the  five  most  extensive  soil  types  of  Illinois. 

TABLE  20.2.     CERTAIN  PLANT-FOOD  ELEMENTS  IN  ILLINOIS  SURFACE  SOILS 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6§  Inches) 


Son. 
TYPE 
No. 

SOIL  AREA 
OR  GLACIATION 

Son.  TYPE 

PHOS- 
PHORUS 
(Total) 

POTAS- 
SIUM 
(Total) 

MAGNE- 
SIUM 
(Total) 

CALCIUM 
(Total) 

135 

Unglaciated 

Yellow  silt  loam 

95° 

3X450 

551° 

439° 

33° 

Lower  Illinoisan 

Gray  silt  loam 

840 

24940 

4690 

3420 

426 

Middle  Illinoisan 

Brown  silt  loam 

1170 

32240 

7460 

9280 

526 

Upper  Illinoisan 

Brown  silt  loam 

I2OO 

32940 

9610 

11060 

1126 

Early  Wisconsin 

Brown  silt  loam 

IIQO 

36250 

8790 

II450 

General  average    

IO7O 

T.iz6o 

72IO 

7Q2O 

Number  of  years'  supply  : 

(a)   Fnr  total  rrnns      .                               . 

r6 

•joe 

424 

188 

(b)  F 

or  grain  only 

IO2 

2475 

1802 

6600 

It  should  be  kept  in  mind  that  these  data  are  based  upon  the 
average  composition  of  many  soil  samples  from  every  type,  and 
that  these  are  widely  representative  of  the  most  extensive  and 
important  soil  types  in  the  Central  states.  They  signify  determined 
facts.  As  a  general  average  of  these  soils,  potassium  is  better 
supplied  than  magnesium  for  grain  farming  (in  which  all  coarse 
products  are  returned  to  the  land),  and  potassium  is  better  sup- 
plied than  calcium  for  a  system  in  which  all  of  the  produce  is  re- 
moved. In  normal  soil  types  the  relations  existing  among  these 
four  elements  in  the  subsoil  are  not  essentially  different  from  those 
in  the  surface,  except  in  subsoils  that  are  rich  in  calcium  and  mag- 
nesium carbonates.  Even  in  the  almost  unweathered  glacial  sub- 
soils of  the  principal  types  of  the  late  Wisconsin  glaciation  (brown 
silt  loam  and  yellow-gray  silt  loam ;  see  Table  17),  2500  pounds  of 
phosphorus  and  158,000  pounds  of  potassium  are  the  relative  and 
total  amounts  of  those  two  elements  per  acre  in  a  2o-inch  stratum. 
Measured  by  the  average  losses  from  the  farm  by  selling  maximum 
crops  of  corn  and  wheat,  our  two  principal  grains,  the  phosphorus 
in  6  million  pounds  of  this  subsoil  is  sufficient  for  173  years,  or 
one  half  as  long  as  from  1565  to  1911,  and  the  potassium  is  sufficient 


io6  SCIENCE   AND   SOIL 

for  9900  years,  or  as  long  as  from  8000  years  before  Christ  to  1903 
years  after  Christ.  In  other  words,  on  the  absolute  mathematical 
basis  there  is  less  of  reason  for  applying  potassium  to  normal 
soils  as  plant  food  than  there  is  for  applying  magnesium  and  cal- 
cium for  the  sake  of  adding  them  also  as  plant  food  (see  page  561). 

The  use  of  potassium  on  soils  actually  deficient  in  that  element 
(as  peaty  swamp  soils) ,  and  on  some  other  soils  as  a  soil  stimulant, 
is  discussed  in  the  following  pages. 

In  brief,  it  may  be  said,  of  the  plant-food  elements  supplied  by  the 
soil,  that  nitrogen  and  phosphorus  are  in  one  class;  that  potassium, 
magnesium,  and  calcium  are  far  removed  in  a  second  class;  and  that 
iron  is  distinctly  in  a  third  class;  while  the  nitrogen  of  the  air,  so 
far  as  concerns  the  supply  for  permanent  agriculture,  should  be 
classed  with  carbon,  hydrogen,  and  oxygen.  The  place  of  sulfur 
is  not  so  easily  determined.  Measured  by  the  soil's  supply,  sulfur 
would  be  classed  with  phosphorus  and  nitrogen;  or  measured  by  the 
crop  demands,  it  would  be  classed  with  iron;  but,  if  both  supply 
and  demand  are  considered,  it  must  be  classed  with  potassium, 
magnesium,  and  calcium.  It  is,  however,  known  with  certainty 
that  more  or  less  sulfur  is  carried  into  the  air  with  the  products  of 
combustion  and  of  decay,'  and  some  sulfates  are  also  carried  into 
the  atmosphere  in  the  dust  from  evaporated  ocean  spray.  Long- 
continued  investigations  at  Rothamsted  and  elsewhere  have  shown 
that  as  an  average  rainfall  brings  to  the  soil,  chiefly  in  the  form  of 
sulfates,  about  7  pounds  of  sulfur  per  acre  per  annum,  or  i  pound 
more  than  would  be  required  for  a  zoo-bushel  crop  of  corn  (p.  57). 

NOTE.  In  New  Hampshire  Agricultural  Experiment  Station  Bulletin  142 
(December,  1909),  Morse  and  Curry  report  37,400  pounds  of  total  potassium 
in  two  million  pounds  of  surface  soil  of  the  uplands,  and  50,000  pounds  in  two 
million  of  surface  soil  of  the  lowlands,  in  the  vicinity  of  Durham,  these  amounts 
representing  averages  of  ten  and  fifteen  respective  soil  analyses  of  clays  and 
clay  loams.  The  summary  of  this  bulletin  contains  the  conclusions  that  the 
potassium  in  these  soils  is  soluble  enough  to  supply  potassium  for  heavy  crops 
of  grass  without  artificial  reenforcement,  and  that  additional  potassium  when 
supplied  in  commercial  fertilizers  does  not  affect  the  yield  or  the  composition 
of  the  grasses. 


CHAPTER  VII 

AVAILABLE   PLANT   FOOD 

"AVAILABLE  plant  food"  is  an  expression  much  used  in  connec- 
tion with  commercial  fertilizers,  and  the  argument  is  commonly 
made  that  because  the  soil  does  net  contain  available  plant  food, 
we  should  therefore  apply  available  plant  food  in  commercial  fer- 
tilizers. Instead  of  following  this  advice,  however,  the  farmer 
should,  as  a  very  general  rule,  adopt  a  system  of  farming  that  will 
make  available  the  plant  food  in  the  soil  so  far  as  practicable,  and, 
if  any  element  is  actually  deficient  in  the  soil,  apply  that  element 
in  cheap  form  and  in  positively  larger  quantities  than  will  be  re- 
moved in  large  crops;  and  then  make  it,  too,  available  by  his 
method  of  farming. 

There  are  three  methods  of  determining  with  some  degree  of 
satisfaction  which  elements,  if  any,  are  deficient  in  the  soil: 

First,  we  may  compute  from  the  composition  of  the  soil  and  the 
requirements  of  crops  the  probable  durability  of  a  soil  with  reference 
to  any  element  of  plant  food.  Thus,  we  may  determine  that  the 
unglaciated  yellow  silt  loam  surface  soil  of  Illinois,  Kentucky, 
Tennessee,  and  other  adjoining  states,  contains  sufficient  nitrogen 
for  less  than  20  large  corn  crops  if  only  the  grain  were  removed; 
while  the  potassium  in  the  late  Wisconsin  brown  silt  loam  is  suffi- 
cient for  more  than  2300  such  crops. 

Second,  we  can  assume  for  a  rough  estimation  that  the  equiva- 
lent of  2  per  cent  of  the  nitrogen,  i  per  cent  of  the  phosphorus,  and 
|  of  i  per  cent  of  the  total  potassium  contained  in  the  surface  soil 
can  be  made  available  during  one  season  by  practical  methods  of 
farming.  Of  course,  the  percentage  that  can  be  made  available  will 
vary  very  much  with  different  seasons,  with  different  soils,  and  for 
different  crops;  and  yet  with  normal  soils  and  seasons  and  for  ordi- 
nary crops  the  above  percentages  represent  roughly  about  the 

107 


io8  SCIENCE  AND   SOIL 

proportion  that  is  liberated  from  our  common  soils  of  the  element 
that  limits  the  yield  of  the  crop. 

In  Table  21  are  given  the  amounts  of  annually  available  plant 
food  in  Illinois  soils  as  roughly  estimated  by  this  method  of  com- 
putation. 

Of  course,  these  amounts  would  be  smaller  and  smaller  year  by 
year  in  proportion  as  the  total  supply  is  decreased,  and  accordingly 
complete  exhaustion  is  not  only  impracticable  and  unprofitable 
because  of  the  continual  reduction  in  crop  yields,  but  it  is  mathe- 
matically impossible,  just  as  it  would  be  impossible  to  exhaust  a 
bank  account  if  only  one  per  cent  of  the  remaining  deposit  could 
be  withdrawn  each  week. 

A  peaty  swamp  soil  containing  2930  pounds  of  total  potassium 
per  acre  in  the  first  6|  inches  would  liberate  during  the  season, 
according  to  this  estimate,  about  7  pounds  of  potassium,  which 
would  be  equivalent  to  a  crop  of  10  bushels  of  corn,  which  represents 
roughly  about  the  average  yield  from  such  land  when  not  treated 
with  potassium,  as  is  shown  in  the  following  pages.  The  common 
brown  silt  loam  prairie  soil,  when  well  farmed,  will  average  about 
50  bushels  of  corn  per  acre,  which  would  require  n^  pounds  of 
phosphorus  and  74  pounds  of  nitrogen,  while  12  and  96  pounds' 
represent  i  per  cent  of  the  phosphorus  and  2  per  cent  of  the  nitro- 
gen, respectively,  in  the  surface  soil,  where  phosphorus  is  the  first 
limiting  element  and  nitrogen  the  second. 

These  illustrations  are  given  not  to  prove  that  this  rough  esti- 
mate is  applicable,  but  rather  to  show  the  basis  which  suggests 
such  a  computation.  It  has  some  value,  chiefly,  perhaps,  in  that 
it  helps  one  to  understand  why  it  is  that  with  phosphorus  enough 
in  the  surface  soil  for  50  crops,  we  obtain  only  half  a  crop  as  an 
average. 

On  this  basis  we  should  try  to  keep  sufficient  phosphorus  in  the 
surface  soil  for  100  large  crops,  of  which  one  per  cent  would  then 
be  sufficient  for  one  large  crop.  This  would  require  about  2300 
pounds  of  phosphorus  per  acre,  or  but  little  more  than  is  actually 
contained  in  the  most  productive  Illinois  corn-belt  soil,  as  the 
early  Wisconsin  black  clay  loam  in  such  counties  as  McLean, 
Champaign,  Edgar,  et  al. 

While  there  are  several  agencies  that  tend  to  convert  insoluble 


AVAILABLE   PLANT   FOOD 


109 


plant  food  into  available  forms,  such  as  the  products  of  decaying 
organic  matter,  including  carbonic,  nitric,  and  various  organic 
acids,  the  different  forms  of  lime,  and  most  soluble  salts,  each  of 
which  is  more  fully  discussed  in  its  proper  place,  it  is  also  known  that 
the  plant  roots  themselves  influence  the  availability  of  plant  food, 
probably  by  means  of  the  carbonic  acid  or  other  substances  which 
they  excrete. 

The  juices  of  plants  are  commonly  distinctly  acid,  and  the  roots 
have  some  power  to  exude  moisture,  which  certainly  contains 
carbonic  acid  and  very  possibly  contains  no  other  solvents,  although 
this  question  is  not  fully  settled.  Where  growing  plant  roots  lie  in 
contact  with  the  polished  surface  of  marble  (calcium  carbonate) 
and  some  other  materials  (as  prepared  slabs  of  calcium  phosphate), 
distinct  etching  occurs,  as  was  early  shown  by  Sachs  and  Czapek. 

Kossowitsch  conducted  an  experiment  in  which  he  grew  plants 
(peas,  flax,  and  mustard)  in  two  pots  of  sand  which  differed  only 
by  the  addition  of  fine-ground  rock  phosphate  to  one.  The  plants 
were  watered  with  the  slow  and  constant  application  of  like 
amounts  of  a  dilute  solution  containing  all  essential  plant-food  ele- 
ments, except  phosphorus.  For  the  pot  which  contained  no  phos- 
phate this  solution  was,  in  this  continuous  process  of  watering, 
passed  through  a  third  pot  of  sand  to  which  the  fine-ground  rock 
phosphate  had  also  been  added. 

Kossowitsch  found  that  the  plants  made  a  much  better  growth 
in  the  pot  where  the  roots  were  in  direct  contact  with  the  phos- 
phate, thus  showing  that  they  exert  a  solvent  action  in  addition 
to  any  that  may  be  exerted  by  the  nutrient  solution. 

If,  for  example,  the  plant  roots  come  in  contact  with,  or  exert 
an  influence  upon,  the  equivalent  of  only  one  per  cent  of  the  sur- 
face of  the  soil  particles  within  the  root  range,  this  would  offer  an 
explanation  of  the  relationship  (which  is  very  irregular  in  different 
soils  and  seasons)  that  exists  between  the  total  amount  of  any 
plant-food  element  in  a  given  soil  stratum  and  the  amount  secured 
by  a  given  crop  during  the  growing  season. 

It  is  well  known  that  soluble  phosphates  and  soluble  potassium 
salts,  when  applied  to  normal  soils,  are  almost  immediately  con- 
verted into  insoluble  forms;  and  the  higher  availability  of  such 
soluble  fertilizers  is  now  Relieved  to  be  largely  due  to  the  fact  that 


no 


SCIENCE   AND    SOIL 


TABLE  21.    ANNUALLY  AVAILABLE  FERTILITY  IN  ILLINOIS  SOILS,  ROUGHLY 

ESTIMATED 
Pounds  per  Acre 


SOIL 

AVAIL- 

AVAIL- 

AVAIL 

TYPE 
No. 

SOIL  AREA  OR  GLACIATION 

Son.  TYPE 

ABLE 
NITRO- 

ABLE 
PHOS- 

ABLE 

POTAS- 

GEN 

PHORUS 

SIUM 

PRAIRIE  LANDS,  UNDULATING 


33° 

Lower  Illinoisan     .     . 

Gray  silt  loam  on  tight  clay 

58 

8 

62 

426 
526 
626 
726 

Middle  Illinoisan   .     . 
Upper  Illinoisan     .     . 
Pre-Iowan     .... 
lowan       

Brown  silt  loam  .     .     . 
Brown  silt  loam  .     .     . 
Brown  silt  loam  .     .     . 
Brown  silt  loam  . 

8? 
97 
86 
08 

12 
12 
12 
12 

8l 
82 

88 
82 

1126 
1026 

Early  Wisconsin     .     . 
Late  Wisconsin      .     . 

Brown  silt  loam   .     .     . 
Brown  silt  loam    .     .     . 

101 

135 

12 
M 

9i 
IJ3 

PRAIRIE  LANDS,  FLAT 


329 

Lower  Illinoisan     .     . 

Drab  silt  loam     .     .     . 

56 

7 

66 

420 

520 

1  1  20 

I22O 

Middle  Illinoisan    .     . 
Upper  Illinoisan     .     . 
Early  Wisconsin     .     . 
Late  Wisconsin      .     . 

Black  clay  loam  .     .     . 
Black  clay  loam  .     .     . 
Black  clay  loam  .     .     . 
Black  clay  loam  .     .     . 

108 
i35 
J57 
178 

14 

i7 

20 
J9 

80 

74 
88 

93 

TIMBER  UPLANDS,  ROLLING  OR  HILLY 


!3S 

Unglaciated  .... 

Yellow  silt  loam   .     .     . 

38 

10 

79 

335 

Lower  Illinoisan     .     . 

Yellow  silt  loam  .     .     . 

43 

10 

80 

345 

Middle  Illinoisan   .     . 

Yellow  silt  loam   .     .     . 

37 

8 

82 

535 

Upper  Illinoisan     .     . 

Yellow  silt  loam   .     .     . 

40 

8 

87 

635 

Pre-Iowan     .... 

Yellow  silt  loam  .     .     . 

48 

9 

93 

735 

lowan       

Yellow  silt  loam  .     .     . 

38 

9 

89 

"35 

Early  Wisconsin     .     . 

Yellow  silt  loam  .     .     . 

38 

9 

82 

864 

Deep  loess    .... 

Yellow  fine  sandy  loam 

43 

10 

89 

TIMBER  UPLANDS,  UNDULATING 


1034 
760 

Late  Wisconsin  .     .     . 
lowan       

Yellow-gray  silt  loam    . 
Brown  sandy  loam  .     . 

58 
61 

8 
9 

119 
67 

TIMBER  UPLANDS,  FLAT 

332 

Lower  Illinoisan     .     . 

Light  gray  silt  loam  on 
tight  clay     .... 

38 

8 

68 

AVAILABLE   PLANT   FOOD 


in 


TABLE  21.   ANNUALLY  AVAILABLE  FERTILITY  IN  ILLINOIS  SOILS,  ROUGHLY 
ESTIMATED  —  Continued 


SOIL 

AVAIL- 

AVAIL- 

AVAIL- 

TYPE 
No. 

Son,  AREA  OR  GLACIATION 

Son.  TYPE 

ABLE 
NITRO- 

ABLE 
PHOS- 

ABLE 
POTAS- 

GEN 

PHORUS 

SIUM 

SAND,  SWAMP,  AND  BOTTOM  LANDS 


1331 

Old  bottom  lands  .     . 

Deep  gray  silt  loam  .     . 

72 

14 

91 

1451 

Late  bottom  lands 

Brown  loam    .... 

94 

16 

100 

1481 

Sand  plains  and  dunes 

Sand  soil    .... 

2Q 

8 

77 

1401 

Late  swamp 

Deep  peat  . 

(?)  » 

20 

7 

1415 

Late  swamp       .     .     . 

Drab  clay  

US 

iQ 

1  2O 

1  The  nitrogen  in  peat  is  so  very  slowly  available  that  not  even  a  rough  estimate 
can  be  made  here. 

they  first  dissolve  in  the  soil  water  and  spread  over  the  surface  of 
the  soil  particles  before  becoming  insoluble,  and  thus  they  offer 
a  much  more  extensive  surface  for  contact  with  plant  roots  than 
would  plant-food  particles  applied  in  insoluble  form,  unless  very 
finely  ground. 

Third,  we  may  apply  different  elements  of  plant  food  to  the  soil 
and  note  the  effect,  if  any,  in  increasing  the  yield  of  crops,  and  thus 
sometimes  discover  what  element  is  most  deficient  in  the  soil. 
One  might  suppose  that  this  would  be  the  best  method,  but  such 
is  not  the  case.  This  method  frequently  gives  erroneous  results 
which,  if  followed,  may  lead  to  land  ruin,  because  the  substance 
applied  may  produce  little  or  no  benefit  on  account  of  the  special 
plant-food  element  it  contains,  but  it  may  act  as  a  powerful  soil 
stimulant  and  thus  liberate  from  the  soil  some  other  entirely  differ- 
ent element  in  which  the  soil  is  already  becoming  deficient.  Thus 
have  many  lands  been  practically  ruined  by  the  use  of  land-plaster 
and  salt,  by  the  improper  use  of  lime,  and  even  by  the  use  of  clover 
merely  as  a  soil  stimulant.  Some  good  illustrations  of  this  action 
of  soluble  salts  are  shown  in  the  following  pages. 

"In  considering  the  general  subject  of  culture  experiments  for  determining 
fertilizer  needs,  emphasis  must  be  laid  on  the  fact  that  such  experiments  should 
never  be  accepted  as  the  sole  guide  in  determining  future  agricultural  practice. 


112  SCIENCE   AND    SOIL 

If  the  culture  experiments  and  the  ultimate  chemical  analysis  of  the  soil  agree 
in  the  deficiency  of  any  plant-food  element,  then  the  information  is  conclusive 
and  final;  but  if  these  two  sources  of  information  disagree,  then  the  culture 
experiments  should  be  considered  as  tentative  and  likely  to  give  way  with 
increasing  knowledge  and  improved  methods  to  the  information  based  on 
chemical  analysis,  which  is  absolute. "  l 

The  plant  food  in  the  subsurface  and  subsoil  is  unquestionably 
)f  some  value,  but  even  the  total  supplies  of  nitrogen  and  phos- 
phorus that  are  held  within  the  feeding  range  of  ordinary  plant 
roots  are  not  unlimited  when  measured  by  crop  requirements  in 
permanent  agriculture.  However,  the  thing  of  first  importance  is 
to  maintain  a  rich  surface  soil,  for  no  subsoil  is  of  much  practical 
value  if  it  lies  beneath  a  worn-out  surface.  On  the  other  hand,  if  the 
subsoil  will  act  as  a  reservoir  for  moisture,  then  a  rich  top  soil  will 
produce  large  crops.  Manures  and  fertilizers  are  applied  to,  and 
incorporated  with,  the  plowed  stratum  only.  On  the  Rothamsted 
fields'  where  chalk  exceeding  100  tons  per  acre  was  applied  to  the 
land  a  hundred  years  ago,  practically  no  calcium  carbonate  is 
found  below  the  plowed  soil  even  after  a  century  of  cultivation, 
although  50  tons  of  the  chalk  applied  still  remain  in  the  surface  soil ; 
and  the  land  fertilized  with  nitrogen,  phosphorus,  and  potassium, 
which  has  yielded  more  than  30  bushels  of  wheat  per  acre  as  an 
average  of  fifty  years,  contains,  as  an  average,  no  more  plant 
food  in  the  strata  below  the  surface  9  inches  than  is  found  in 
the  same  strata  where  the  land  has  been  unfertilized  and  has 
produced  an  average  yield  of  only  13  bushels  of  wheat  for  the 
same  fifty  years. 

\i  The  supply  of  nitrogen  in  soils  is  contained  only  in  the  organic 
matter;  and  thus  the  amount  of  nitrogen  in  the  subsoil  of  normal 
soil  types  is  relatively  small,  as  will  be  seen  from  a  study  of  Tables 
15,  16,  and  17,  six  million  pounds  of  subsoil  containing,  as  a  rule, 
less  nitrogen  than  two  million  pounds  of  surface,  except  where  the 
surface  is  much  worn.  The  small  amount  of  humus  in  the  subsoil 
is  also  quite  inactive,  and  the  liberation  of  nitrogen  from  its  decom- 
position is  very  slight.  Furthermore,  in  all  humid  regions  there  is 
large  loss  of  nitrogen  in  drainage  waters;  so  that  in  practice  the 
addition  of  nitrogen  to  the  surface  soil  must  be  somewhat  greater 

1  "Cyclopedia  of  American  Agriculture,"  Vol.  I,  page  475. 


AVAILABLE   PLANT   FOOD 

than  that  removed  in  crops,  if  the  productive  power  of  the  soil  is 
maintained. 

The  phosphorus  of  the  soil  exists  in  both  organic  and  mineral 
forms.  While  the  supply  of  mineral  phosphorus  is  likely  to  be  smaller 
in  the  surface  and  subsurface  than  in  the  subsoil,  the  organic 
phosphorus,  like  nitrogen,  varies  with  the  organic  matter,  which, 
as  a  rule,  decreases  rapidly  below  the  plowed  soil.  As  a  consequence, 
there  is  usually  less  phosphorus  in  the  subsurface  than  in  the  sur- 
face, unless  the  surface  is  very  poor  in  organic  matter;  and  also 
there  is  less  phosphorus  in  the  subsurface  than  in  the  subsoil, 
unless  the  subsurface  is  much  richer  in  organic  matter.  A  larger 
supply  of  phosphorus  in  the  surface  than  in  the  subsurface  is  suffi- 
cient to  prove  that  plants  secure  some  phosphorus  from  below  the 
surface  soil,  because  the  excess  of  phosphorus  in  the  surface  is 
contained  in  the  decomposition  products  of  plant  residues  from  the 
centuries  gone  by.  Where  the  subsoil  is  richer  in  phosphorus  than 
the  subsurface,  it  indicates  either  that  phosphorus  has  been  lost 
from  the  subsurface  by  leaching  or  that  the  plant  roots  have  with- 
drawn phosphorus  from  the  subsurface  to  a  greater  extent  than 
from  the  subsoil. 

With  the  brown  silt  loams  and  black  clay  loams  of  the  corn  belt, 
the  surface  stratum  rich  in  organic  matter  is  always  richer  in  phos- 
phorus than  the  subsurface;  and,  with  one  exception,  the  subsur- 
face, which  is  also  quite  well  supplied  with  organic  matter,  is  richer 
in  phosphorus  than  the  subsoil,  but  the  other  upland  soils  contain 
less  organic  matter  in  the  surface  and  much  less  in  the  subsurface, 
and  the  subsoil,  with  a  single  exception,  is  richer  in  phosphorus  than 
the  subsurface,  equal  weights  of  soil  always  being  considered. 

The  potassium  is  contained  almost  solely  in  the  mineral  part  of 
the  soil,  and  the  supply  regularly  increases  with  depth,  the  sub- 
surface being  richer  than  the  surface  and  the  subsoil  still  richer. 


CHAPTER  VIII 

SOIL   SURVEYS  BY  THE  UNITED   STATES  BUREAU  OF   SOILS 

THE  Bureau  of  Soils  of  the  United  States  Department  of  Agricul- 
ture was  organized  in  1895,  with  Professor  Milton  Whitney  as 
Chief.  The  energies  of  this  Bureau  have  been  devoted  largely  to 
making  surveys  of  the  soils  in  certain  localities  in  most  of  the 
different  states;  and,  second,  to  laboratory  investigations  in  sup- 
port of  a  theory  early  announced  by  Whitney  and  Cameron,  to 
the  effect  that  practically  all  soils  contain  sufficient  plant  food  for 
good  crop  yields,  and  that  this  supply  will  be  indefinitely  main- 
tained. 

The  soil  surveys  are  of  general  interest  but  of  doubtful  value  to 
the  local  farmers  and  landowners,  because  they  are  reported  with 
practically  no  information  concerning  valuable  methods  of  soil 
improvement  other  than  that  based  upon  the  actual  practice  al- 
ready in  vogue,  the  Bureau  having  conducted  no  systematic  field 
experiments  and  having  reported  practically  no  chemical  analyses 
of  the  various  soil  types  identified.  The  mechanical  analyses  which 
are  almost  invariably  reported  give  little  information  of  value  fur- 
ther than  to  support  the  soil  surveyor's  classification  of  the  soils 
into  sandy  soils,  silty  soils,  clay  soils,  etc.  Even  the  soil  sur- 
vey, as  conducted  by  the  Bureau,  is  often  too  general  or  superficial 
in  character  to  be  of  local  use,  differences  in  soils  which  are  clearly 
recognized  by  the  farmers  being  often  ignored  or  overlooked. 
This  will  be  better  understood  by  examination  of  concrete  illus- 
trations ;  such,  for  example,  as  a  comparison  of  the  Bureau's  map 
of  Tazewell  County,  Illinois,  published  in  the  Report  of  Field 
Operations*  for  1902,  with  that  of  McLean  County,  which  joins 
Tazewell  on  the  east,  and  which  accompanies  the  Report  for  1903; 
or  by  a  comparison  of  the  Bureau's  map  of  Clay  County,  Illinois 

114 


SURVEYS   BY   THE   UNITED   STATES   BUREAU     115 

(1902),  showing  all  of  the  upland,  comprising  85  per  cent  of  the 
county,  as  one  soil  type  (Marion  silt  loam),  with  the  detail  soil 
map  published  by  the  University  of  Illinois  Agricultural  Experi- 
ment Station  (1911),  showing  eleven  different  types  of  upland 
soil,  most  of  which  are  commonly  recognized  by  the  local  farmers, 
the  most  extensive  type  (gray  silt  loam  on  tight  clay,  or  "  typical  " 
Marion  silt  loam)  comprising  only  37  per  cent  of  the  county. 
These  upland  soil  types  vary  in  agricultural  value  from  $15  to 
$60  an  acre.  They  vary  in  average  composition  from  uoo  pounds 
of  nitrogen  and  40x3  pounds  of  phosphorus  to  3890  pounds  of  nitro- 
gen and  820  pounds  of  phosphorus  in  2  million  pounds  of  the  sur- 
face soil.  On  more  than  15,000  acres  of  the  level  upland  prairie 
soil,  surface  drainage  can  be  provided  only  with  much  diffi- 
culty, while  40,000  acres  of  .eroded  timberlands  are  so  rough 
that  the  soil  ought  not  to  be  kept  under  cultivation.  About  30 
per  cent  of  the  upland  is  not  underlain  with  tight  clay,  while  the 
remainder  has  the  subsoil  sometimes  called  "  hardpan  "  by  the 
resident  farmers. 

These  facts  are  mentioned  in  order  that  the  student  may  under- 
stand that  the  soil  survey  as  made  by  the  Bureau  of  Soils  is  not 
intended  to  be  in  sufficient  detail  for  local,  specific  use.  To  quote 
Professor  Whitney's  language  from  a  letter  to  the  author  under 
date  of  March  26,  1903: 

"In  the  work  on  the  scale  in  which  the  Bureau  is  engaged,  we  cannot  recog- 
nize differences  that  might  and  should  be  recognized  in  a  more  detailed  survey 
of  a  limited  area.  It  is  necessary  for  us  to  show  only  important  differences  in 
the  soils  which  will  be  of  value  to  the  people  of  large  areas. " 

Nevertheless,  the  soil  surveys  of  the  Bureau  have  large  value  as 
a  source  of  general  information  concerning  the  soils  of  the  United 
States.  The  author  has  very  great  respect  for  the  art  of  surveying 
soils,  whether  for  general  information  over  broad  areas  or  for  spe- 
cific use  where  the  details  are  mapped. 

The  accompanying  map  of  the  United  States,  showing  "  Soil 
Provinces,"  as  published  by  the  Bureau  of  Soils,  is  based  in  part 
upon  the  work  of  the  United  States  Geological  Survey.  Within 
these  14  great  soil  provinces,  the  Bureau  of  Soils  had  recognized 
(previous  to  January  i,  1908)  different  soil  types  to  the  number  of 


n6  SCIENCE   AND   SOIL 

715,  most  of  which  have  been  grouped  into  86  soil  series;  and  the 
following  extracts  from  Bureau  of  Soils  Bulletin  55  (1909),  de- 
scriptive of  these  soils,  cannot  fail  to  be  of  interest  and  value  to 
the  student  of  American  soils. 

CLASSIFICATION  OF  SOILS 

"The  texture  of  the  soil  is  expressed  in  the  mechanical  analysis  by  a  separa- 
tion into  seven  grades,  the  sizes  of  which  are  arbitrarily  fixed.  The  results  of 
the  analysis  show  the  percentages  of  sand,  silt,  and  clay. " 

"When,  aside  from  texture,  the  physical  and  chemical  properties  of  the 
soil  and  its  method  of  formation  are  alike,  we  have  what  we  call  a  soil  series, 
extending  from  the  coarse  gravelly  or  sandy  soils  on  the  one  side  to  the  finer 
silt  and  clay  soils  on  the  other,  and  in  such  a  series  the  texture  of  the  soil  deter- 
mines the  distribution  of  crops. 

"  It  would  be  a  comparatively  simple  matter  to  compare  and  classify  soils 
according  to  the  mechanical  analysis  or  texture,  but  this  standard  alone  is 
not  sufficient,  and  the  problem  is  in  reality  a  very  difficult  thing,  for  in  working 
out  the  relation  of  the  soils  to  crops,  other  factors  enter  which  must  be  recognized 
in  the  correlation.  One  of  the  most  important  of  these  is  the  structure  or 
the  arrangement  of  the  mineral  matter.  In  some  soils  the  mineral  particles 
have  a  granular  arrangement  of  flocculated  masses,  making  the  soil  loose  and 
porous.  In  others  the  grains  appear  to  have  no  such  coherency,  but  exist  in 
a  compact  form,  making  the  soil  hard  and  compact.  We  also  have  the  gumbo 
and  adobe  soils  and  others  that  are  exceedingly  plastic.  Then,  again,  the 
amount  and  character  of  the  organic  matter  influences  not  only  the  productive 
capacity  of  the  soil,  but  its  adaptation  to  crops,  while  the  color  of  the  soil  has 
to  be  considered  as  indicative  of  certain  obsure  chemical  or  physical  relations 
that  influence  the  adaptation  and  productivity.  The  drainage  features  also 
come  in,  often  with  material  influence  on  the  organic  constituents,  on  the  aera- 
tion, and  on  oxidation  processes. " 

"The  experienced  soil-survey  man  can  judge  very  accurately  of  the  texture  of 
the  soil  material,  but  even  his  judgment,  before  being  accepted,  is  always 
confirmed  by  mechanical  analysis. 

"  Where  soils  have  a  common  origin  and  differ  only  in  texture  and  are  alike  in 
color  and  in  physical  properties  other  than  those  affected  by  texture,  they  are 
arranged  in  what  we  call  a  series  having  the  soil  generic  name  with  qualifying 
textural  terms.  We  have,  for  example,  the  Miami  gravelly  loam,  the  Miami 
fine  sand,  the  Miami  sandy  loam,  the  Miami  silt  loam,  and  the  Miami  clay 
loam  as  prominent  types  in  the  Miami  series.  In  this  particular  series  we 
have  fourteen  types,  and  possibly  two  or  three  other  types  will  be  encountered. 
In  the  Norfolk  series  we  have  twelve  types." 

"If  the  texture  and  structure  of  two  soils  is  the  same,  and  one  differs  in  a 
marked  degree  from  the  series  color,  and  that  departure  is  fairly  constant  and 


Appalachian  Mountains 
and  Plateaus 


Northwestern 
Intermountain  Regions 


M 


*, 


L    F  OF 


b 
M    E    X    I   C  \0  k 

V9* 


<J>\       ^ 


'.       U      -L,      f  ^      * 

1 

UNITED  STATES  SOIL  PROVINCES 

Reduced  from  maps  of  U.S.  Geological  Survey 


Reduced  from  maps  of  U.S.  Geological  Survey 
and  Bureau  of  Soils 

_  SCALE  OF  MILES  _ 

o          loo        200        §5o        loo        sbo 


V      ** 


^ 


95  from  90  Greenwich          85 


SURVEYS    BY   THE   UNITED   STATES   BUREAU 


117 


typical  of  the  area  covered  by  the  soil,  this  soil  likewise  is  thrown  out  of  the 
series,  because  we  have  reason  to  know,  by  observation  of  the  growing  crops, 
that  this  color  difference  stands  for  a  difference  in  the  chemical  changes  which 
go  on  in  the  soil  and  which  are  necessary  for  the  welfare  of  certain  crops. 

"  In  the  classification  of  soils,  therefore,  the  texture  is  used  to  determine  the 
place  in  the  series;  the  structure  and  color  to  determine  what  series  the  soil 
can  be  correlated  with. " 

The  following  table  gives  the  name  and  area  of  the  soil  provinces  and  the 
proportion  of  each  that  has  been  covered  by  the  soil  survey.  It  is  not  unlikely 
that  as  the  work  progresses  and  as  our  knowledge  of  the  soils  increases  it  will 
seem  advisable  to  divide  some  of  these  provinces  into  two  or  more  parts. 

SOIL  PROVINCES  OF  THE  UNITED  STATES 


PROVINCE 

ESTIMATED 
AREA 

AREA  SURVEYED 

Atlantic  and  Gulf  coastal  plains   .     .     . 
River  flood  plains       

Acres 
233000000 
64000000 
48000000 
72OOOOOO 
68000000 
455OOOOOO 
4IOOOOOO 
107000000 
109000000 
76000000 
365000000 
58000000 
2IOOOOOO 
2IIOOOOOO 

Acres 
25613666 
8061247 
7271798 
6367009 
6052926 
2241  7832 
5091882 
1825850 
1005600 
1455428 
2939840 

H3H55 
4593881 

Per  Cent 
10 
13 
15 
9 
9 

5 

12 

2 
I 
2 
I 
2 
22 

Piedmont  Plateau       

Appalachian  Mountains  and  plateaus   . 
Limestone  valleys  and  uplands     .     .     . 
Glacial  and  loessial    

Glacial  lake  and  river  terraces  .... 
Residual  soils  of  Western  prairie  .     .     . 
Great  Basin       

Northwestern  intermountain  region  .     . 
Rocky  Mountain  valleys  and  plains  .     . 
Arid  Southwest      

Pacific  coast      

Western  mountain  regions  
Total     

1928000000 

93828114 



ATLANTIC  AND  GULF   COASTAL  PLAINS 

The  Atlantic  and  Coastal  plains  together  constitute  one  of  the  most  impor- 
tant physiographic  divisions  of  the  United  States.  The  Atlantic  Coastal  Plain 
extends  from  the  New  England  states  southward  to  the  Florida  Peninsula, 
where  the  Gulf  Coastal  Plain  begins,  and  extends  thence  westward  to  the 
Mexican  boundary  line.  It  is,  however,  discontinuous,  being  interrupted  by 
the  alluvial  bottoms  of  the  Mississippi  River.  From  the  coast  the  Atlantic 
Plain  extends  inland  to  the  margin-of  the  Piedmont  Plateau;  that  is,  to  a 
line  passing  through  Trenton,  Baltimore,  Washington,  Richmond,  Raleigh, 
Columbia,  Augusta,  and  Macon.  In  its  northern  extension  it  is  represented 
by  a  narrow  belt,  but  widens  in  New  Jersey,  and  attains  its  maximum  breadth 


n8  SCIENCE   AND   SOIL 

of  about  200  miles  in  North  Carolina.  The  Gulf  Plain  extends  up  the  Missis- 
sippi to  the  mouth  of  the  Ohio,  its  inner  boundary  line  passing  through  or  near 
Montgomery,  luka,  Cairo,  Little  Rock,  Texarkana,  Austin,  and  San  Antonio. 

The  surface  is  that  of  a  more  or  less  deserted  plain  marked  by  few  hills, 
slightly  terraced  with  bluffs  along  streams.  The  inner  margin  of  the  Coastal 
Plain  is  usually  from  200  to  300  feet  above  tide  water,  but  sometimes  rises  to  500 
feet.  The  drainage  here  is  usually  well  established,  and  the  surface  is  rolling 
to  hilly,  and  consequently  carved  and  eroded.  There  is  a  wide  belt  border- 
ing the  coast  where  the  elevations  are  mostly  under  100  feet.  North  of  the 
James  River,  where  the  Coastal  Plain  is  narrow  and  deeply  indented  with 
tidal  estuaries,  drainage  is  usually  well  established  and  the  surface  is  rolling, 
but  in  the  broad  southern  extension,  where  the  seaward  slope  is  hardly  more 
than  i  foot  to  the  mile,  drainage  is  apt  to  be  deficient.  Here  rain  water  often 
remains  upon  the  surface  for  a  considerable  time,  although  the  conditions 
are  not  comparable  with  those  of  a  true  swamp.  The  soils  in  this  level  section, 
while  composed  largely  of  sand,  are  compact,  usually  deficient  in  organic 
matter,  and  not  very  productive.  Many  of  the  flat  interstream  areas  possess 
such  poor  drainage  that  true  swamps,  such  as  the  Dismal  and  Okefenokee, 
have  .been  formed.  Near  the  coast  and  along  the  tidal  estuaries,  extensive 
marshes,  separated  from  the  ocean  by  sand  barriers,  are  found. 

The  Coastal  Plain  is  made  up  of  unconsolidated  gravels,  sands,  and  sandy 
clays,  with  less  frequent  beds  of  silts  and  heavy  clays.  The  desposits  on  the 
Atlantic  coast  have  been  derived  mainly  from  the  erosion  of  the  Piedmont 
Plateau  and  other  inland  areas,  while  the  deposits  on  the  Gulf  coast  have  been 
derived  mainly  from  transported  glacial  material  and  from  western  plains. 
The  materials  have  been  transported  and  deposited  beneath  the  sea  and 
subsequently  exposed  by  the  uplift  of  the  ocean  floor.  In  the  more  northern 
parts  of  the  Coastal  Plain,  and  even  as  far  south  as  Virginia,  the  character 
of  the  deposits  has  been  modified  by  glacial  action  and  the  flooded  condition 
of  the  streams  resulting  from  the  melting  of  the  ice. 

The  Coastal  Plain  deposits  range  in  age  from  Cretaceous  to  Recent.  Al- 
though extensive  areas  of  the  older  sediment  are  exposed  at  the  surface  to 
form  soils,  still  by  far  the  greater  part  of  the  materials  is  Quarternary  or  Recent 
in  age. 

The  soils  are  for  the  most  part  composed  of  sands  and  light  sandy  loams, 
with  occasional  deposits  of  silts  and  heavy  clays.  The  heavy  clays  are  found 
principally  near  the  inner  margin  of  the  Coastal  Plain.  The  silts,  silty  clays, 
and  black  calcareous  soils,  upon  which  the  rice  and  sugar-cane  industries  of 
southern  Louisiana  and  Texas  are  being  so  extensively  developed,  have  no 
equivalents  in  the  Atlantic  division. 

Bastrop  series.  Brown  soils  with  reddish  brown  to  red  subsoils  occurring 
as  nonoverflow  terraces.  Cotton,  corn,  sorghum,  alfalfa,  melons,  and  potatoes 
are  successfully  produced. 

Crockett  series.  Dark  gray  prairie  soils  underlain  by  mottled  red  sub- 
soils. Derived  from  slightly  calcareous  material,  the  soils  of  this  series  are 


SURVEYS   BY   THE   UNITED   STATES   BUREAU     119 

productive.  Cotton  and  the  general  farm  crops  are  the  leading  products. 
The  gravelly  soil  is  early  and  adapted  to  early  truck. 

Elkton  series.  Light  gray  to  white  surface  soils,  with  mottled  whitish  gray 
and  yellow  subsoils,  overlying  gravel  and  coarse  sands. 

Gadsden  series.  Gray  soils,  with  subsoils  of  similar  texture  occupying 
gentle  slopes  and  depressions  and  formed  by  wash  or  creep  from  higher  areas. 
This  series  occurs  in  rather  local  development,  particularly  in  Florida,  southern 
Georgia,  and  Alabama.  They  are  very  productive  soils  and  well  adapted  to 
tobacco.  No  heavy  members  of  the  series  have  been  encountered,  and  it  is 
doubtful  if  any  exist. 

Guin  series.  Gray  soils  with  brown  to  yellowish  red  subsoils,  occurring 
as  rolling  and  hilly  lands.  Intermediate  series  between  the  Norfolk  and 
Orangeburg  series.  Owing  to  the  rather  rough  topography,  these  soils  have 
not  been  developed  as  much  as  either  of  the  other  series,  although  they 
seem  capable  of  producing  better  crops  than  they  do  now. 

Houston  series.  Dark  gray  or  black  calcareous  prairies.  One  of  the  most 
productive  series  for  Upland  cotton  and  well  adapted  to  alfalfa  and  other 
forage  crops. 

Laredo  series.  Gray  to  light  brown  calcareous  soils  with  gray  subsoils. 
Good  cotton,  corn,  and  sugar-cane  soils,  and  especially  adapted  to  the  early 
production  of  vegetables  —  cabbage  and  onions  in  particular. 

Lufkin  series.  Light-colored  soils  with  heavy  mottled  gray  and  yellow 
subsoils.  The  soils  of  this  series  have  only  a  moderate  degree  of  productivity. 

Montrose  series.  Gray  soils  with  heavy  plastic  mottled  yellow  subsoils. 
These  soils  are  in  part  poorly  drained,  but  where  cultivated  they  produce 
moderate  yields  of  cotton  and  corn. 

Myatt  series.  Gray  soils  with  mottled  yellow,  gray,  and  whitish  subsoils 
occurring  in  poorly  drained  areas  around  heads  of  streams  and  intermediate 
between  uplands  and  bottom  lands.  The  series  seems  to  be  of  local  extent 
and  but  little  developed. 

Norfolk  series.  Light-colored  soils  with  yellow  sand  or  sandy  clay  sub- 
soils. This  series  contains  some  of  the  most  valuable  truck  soils  of  the  Atlantic 
and  Gulf  Coast  states,  and  certain  members  of  the  series  are  adapted  under 
certain  climatic  conditions  to  wheat,  grass,  tobacco,  and  fruit. 

Oktibbeha  series.  Gray  soils  with  brown  to  yellowish  brown  heavy  sub- 
soils related  to  Houston  series  in  origin.  The  soils  of  this  series  are  distinctly 
inferior  to  the  soils  of  the  Houston  series  and,  as  they  appear  to  cover  large 
areas  in  Mississippi  and  Alabama,  present  a  difficult  problem  in  soil  improve- 
ment. 

Orangeburg  series.  Light-colored  soils  with  red  sandy  clay  subsoils. 
This  series  constitutes  some  of  the  best  cotton  soils  of  the  South,  and  certain 
members  of  the  series  are  particularly  adapted  to  tobacco. 

Portsmouth  series.  Dark -colored  soils  with  yellow  or  mottled  gray  sand 
or  sandy  clay  subsoils.  Where  drainage  is  adequate,  this  series  is  adapted 
to  some  of  the  heavier  truck  crops,  to  small  fruits,  and  to  Indian  corn. 


120  SCIENCE  AND    SOIL 

Sassafras  series.  Yellowish  brown  surface  soils  with  reddish  yellow  to 
light  orange  subsoils  overlying  gravel  beds. 

Susquehanna  series.  Gray  soils  with  heavy  red  clay  subsoils  which  become 
mottled  and  variegated  in  color  in  the  deep  subsoil.  Only  one  member  of 
this  series,  the  sandy  loam,  has  been  developed  to  any  considerable  extent. 
This  one  is  used  for  fruit  and  general  farm  purposes,  but  the  other  members 
are  particularly  refractory  and  difficult  to  bring  into  a  productive  state. 

Webb  series.  Brown  to  reddish  brown  soils  with  reddish  brown  to  red  sub  - 
soils,  a  semiarid  prototype  of  the  Orangeburg  series.  The  soils  of  this  series 
have  not  been  used  to  any  great  extent,  owing  to  lack  of  irrigation  facilities. 

Wickham  series.  Reddish  or  reddish  brown  terrace  soils  overlying  reddish, 
micaceous  heavy  sandy  loam  or  loam  subsoils.  The  soils  of  this  series  have  a 
relatively  high  productivity  for  general  farm  crops. 

Wilson  series.  Dark  gray  prairie  soils  with  mottled  gray  subsoils.  The 
clay  member  of  this  series  is  a  strong  soil  devoted  to  general  farming,  with  cotton 
as  the  leading  crop.  The  other  members  are  used  for  cotton,  but  are  inclined 
to  be  droughty. 

RIVER  FLOOD  PLAINS 

An  extensive  and  characteristic  group  of  soils,  usually  known  as  "  bottom 
lands,"  is  found  in  the  flood  plains  of  numerous  rivers  and  streams  of  the 
United  States.  The  largest  development  of  this  group  occurs  along  the  Mis- 
sissippi River,  where  the  bottoms  are  often  many  miles  in  width. 

The  soils  have  been  formed  by  deposition  from  stream  waters  during 
periods  of  overflow.  The  texture  of  the  material  depends  upon  the  velocity  of 
the  current  at  the  time  of  the  deposition.  Where  the  current  is  very  rapid, 
large  stones  and  bowlders  are  borne  along,  and  beds  of  gravel  and  sand  are 
formed.  Along  the  swift-flowing  streams  the  texture  of  the  soil  changes  often 
within  short  distances,  but  in  wide  bottoms  large  areas  of  very  uniform  soils  are 
often  formed.  The  soil  material  has  usually  been  derived  from  various  kinds 
of  rocks,  but  in  some  instances  is  closely  related  to  the  surrounding  geological 
formation.  The  red  soils  along  the  Red  and  other  rivers  in  the  Southwest 
have  been  formed  by  the  reworking  of  the  Permian  Red  Beds.  In  general, 
the  soils  along  the  streams  which  flow  through  the  prairie  region  have  a  darker 
color  than  those  along  the  streams  which  run  only  through  the  timbered  sec- 
tions of  the  country. 

The  difference  in  the  origin,  drainage,  color,  and  organic-matter  content  has 
given  rise  to  several  series  of  alluvial  soils  in  the  humid  portion  of  the  United 
States. 

Congaree  series.  Brown  or  reddish  brown  soils  found  along  Piedmont 
streams  and  representing  wash  from  Cecil  soils.  Valuable  and  dependable 
corn  soils,  but  too  low  and  moist  for  cotton. 

Huntington  series.  Dark  brown  to  yellowish  brown  soils  occurring  along 
streams  in  the  Alleghany  plateaus.  Both  the  general  farm  crops  and  truck 
crops  thrive  on  these  soils. 


SURVEYS   BY   THE   UNITED   STATES   BUREAU     121 

Miller  series.  Brown  to  red  alluvial  soils  formed  from  the  reworking  of 
materials  derived  from  the  Permian  Red  Beds.  Very  productive  soils  suit- 
able for  cotton,  corn,  sugar  cane,  alfalfa,  and  vegetables;  especially  adapted 
to  peaches. 

Ocklocknee  series.  Gray  to  yellowish  brown  soils  found  along  streams  in 
Coastal  Plain  Georgia,  Alabama,  and  Mississippi.  Cotton,  corn,  and  pastur- 
age are  the  leading  products. 

Wabash  series.  Dark  brown  or  black  soils  subject  to  overflow.  Very  pro- 
ductive soils  used  for  cotton,  sugar  cane,  corn,  wheat,  oats,  grass,  alfalfa, 
sugar  beets,  and  potatoes  and  other  vegetables. 

Waverly  series.  Light -colored,  alluvial  soils  subject  to  overflow.  Less  pro- 
ductive than  the  Wabash  soils,  but  adapted  to  the  same  wide  range  of  crops. 

Wheeling  series.  Brown  to  yellowish  brown  soils  occurring  on  gravel  ter- 
races along  streams  issuing  from  glaciated  regions.  Excellent  soils  for  general 
farming,  and  fruit  and  truck  growing. 

PIEDMONT  PLATEAU 

Lying  between  the  Atlantic  Coastal  Plain  and  the  Appalachian  Moun- 
tains and  extending  from  the  Hudson  River  to  east-central  Alabama  is  an  area 
of  gently  rolling  to  hilly  country  known  as  the  Piedmont  Plateau.  On  the 
Atlantic  side  it  is  closely  defined  by  the  "fall  line,"  which  separates  it  from  the 
Coastal  Plain,  but  on  the  northwestern  side  the  boundary  is  not  sharp,  although 
in  the  main  distinct.  In  its  northern  extension  the  Piedmont  Plateau  is 
quite  narrow,  but  broadens  toward  the  south,  attaining  its  greatest  width  in 
North  Carolina. 

The  surface  features  are  those  of  a  broad  rolling  plain  that  has  been  deeply 
cut  by  an  intricate  system  of  small  streams,  whose  valley  walls  are  rounded  and 
covered  with  soil,  although  many  small  gorges  and  rocky  areas  occur.  The 
altitude  varies  from  about  300  feet  to  more  than  1000  feet  above  sea  level. 

The  extreme  northern  part  of  the  Piedmont  region,  in  New  Jersey,  has  been 
glaciated,  but  elsewhere  the  soils  are  purely  residual  in  origin  and  have  been 
derived  almost  exclusively  from  the  weathering  of  igneous  and  metamorphic 
rocks.  The  chief  exception  is  the  detached  areas  of  sandstones  and  shales  of 
Triassic  age.  Marked  differences  in  the  character  of  the  rock  and  the  method 
of  formation  has  given  rise  to  a  number  of  soil  types,  those  derived  from  crys- 
talline rocks  being  the  most  numerous  and  widely  distributed.  Among  these 
the  soils  of  the  Cecil  and  Chester  series  predominate.  The  principal  types 
formed  from  the  sandstones  and  shales  are  included  in  the  Penn  series. 

Cecil  series.  Gray  to  red  soils  with  bright  red  clay  subsoils,  derived  from 
igneous  and  metamorphic  rocks.  Constituting  by  far  the  larger  portion  of  the 
province,  these  soils  are  well  adapted  to,  and  used  for,  cotton,  export  tobacco, 
and  fruit,  and  the  lighter  members  for  truck  crops.  As  a  rule,  they  are  not 
highly  developed,  but  where  properly  handled  the  heavier  members  produce 
excellent  crops  of  corn  and  grazing  and  hay  grasses. 


122  SCIENCE   AND   SOIL 

Chester  series.  Gray  to  brown  surface  soils  with  yellow  subsoils,  derived 
principally  from  schists  and  gneisses.  The  most  valuable  soils  of  the  province 
for  wheat  and  corn,  and  good  for  certain  fruits.  The  most  highly  developed 
soils  of  the  Piedmont  Plateau. 

Penn  series.  Dark  Indian  red  soils  with  red  subsoils,  derived  from  red  sand- 
stones and  shales  of  Triassic  age.  Excellent  soils  for  general  farm  crops, 
particularly  wheat,  corn,  and  hay. 

APPALACHIAN  MOUNTAINS  AND  PLATEAU 

The  Appalachian  Mountains  are  made  up  of  a  number  of  parallel  ranges  and 
intervening  valleys,  which  extend  in  a  general  northeast  and  southwest  di- 
rection from  southern  New  York  to  northern  Alabama.  The  elevation  ranges 
from  about  1500  to  nearly  7000  feet  above  sea  level,  the  highest  point  being 
attained  in  western  North  Carolina. 

Immediately  east  of  the  Appalachian  Mountains,  and  usually  separated  from 
them  by  a  valley,  is  a  wide  stretch  of  country  known  as  the  Alleghany  Plateau. 
In  a  broad  way  this  plateau  is  carved  out  of  a  great  block  of  sedimentary  rocks 
tilted  to  the  northwest  from  the  mountains.  It  is  crossed  by  numerous  streams. 
As  they  run  in  deep  channels  (all  the  larger  ones  being  from  200  to  1000  feet 
in  depth),  the  dissection  of  the  plateau  block  is  often  minute. 

The  rocks  of  the  eastern  ranges  of  the  Appalachian  Mountains  are  igneous 
or  metamorphic  in  origin,  while  the  western  ranges,  as  well  as  the  Alleghany 
Plateau,  are  made  up  of  sedimentary  rocks.  Different  series  of  soils  have, 
therefore,  been  formed  in  different  parts  of  these  mountains  and  plateau. 
The  igneous  and  metamorphic  rocks  give  rise  to  the  soils  of  the  Porter  series, 
while  the  Dekalb  and  Upshur  series  are  formed  from  the  weathering  of  the 
sandstones  and  shales  of  sedimentary  origin. 

The  character  of  the  topography  in  the  mountain  and  much  of  the  plateau 
region  is  such  that  general  farming  is  not  practicable.  These  areas  are,  how- 
ever, well  suited  to  grazing  and  fruit  growing,  and  these  are  very  important 
industries. 

Dekalb  series.  Brown  to  yellow  soils  with  yellow  subsoils,  derived  from 
sand  stones  and  shales.  Soils  of  this  series  are  used,  according  to  texture, 
elevation,  exposure,  and  character  of  surface,  either  for  the  production  of 
hay,  for  pasture,  or  for  orchard  and  small  fruits. 

Fayetteville  series.  Grayish  brown  to  brown  soils  with  yellowish  or  reddish 
brown  subsoils.  Adapted  to  apples,  grapes,  and  small  fruits,  and  give  mod- 
erate yields  of  general  farm  crops. 

Porter  series.  Gray  to  red  soils  with  red  clay  subsoils,  derived  from 
igneous  and  metamorphic  rocks.  This  is  the  greatest  mountain  fruit  series 
of  the  eastern  United  States.  It  is  also  used  for  general  farming. 

Upshur  series.  Brown  to  red  soils  with  red  subsoils,  derived  from  sand- 
stones and  shales.  Somewhat  more  productive  than  the  Dekalb  soils.  Used 
for  cotton,  corn,  wheat,  and  forage  crops. 


SURVEYS   BY  THE   UNITED   STATES   BUREAU      123 

LIMESTONE  VALLEYS  AND  UPLANDS 

The  limestone  soils  are  among  the  most  extensively  developed  of  any  in  the 
United  States  and  occur  in  both  broad  upland  and  inclosed  narrow  valley  areas. 
The  greatest  upland  development  is  seen  upon  the  Cumberland  Plateau  in 
eastern  Tennessee  and  Kentucky  and  upon  the  Carboniferous  formation  in 
central  Tennessee  and  Kentucky,  northern  Alabama  and  Georgia,  and  in 
Missouri.  The  valley  soils  are  found  principally  in  Pennsylvania,  Maryland, 
and  Virginia,  and  in  the  mountain  section  of  eastern  Tennessee  and  Kentucky 
and  northern  Alabama  and  Georgia.  The  topography  of  the  plateau  soils 
varies  considerably.  In  the  Cumberland  Plateau  and  Highland  Rim  the  sur- 
face is  undulating ;  in  the  region  of  the  Ozark  uplift  in  Missouri  and  Arkansas 
it  is  quite  rough  and  hilly,  and  where  there  is  an  elevation  of  the  surface,  or 
where  the  plateau  is  deeply  dissected  by  erosion,  it  presents  a  quite  mountain- 
ous topography.  The  valley  soils  of  the  Appalachian  region  also  show  consider- 
able topographic  relief,  sometimes  exhibiting  mountainous  surface  features. 

The  limestone  soils  are  residual  in  origin,  being  derived  from  the  weather- 
ing in  place  of  limestone  of  differing  age  and  composition.  This  is  accom- 
plished by  the  removal  through  solution  of  the  calcium  carbonate  of  the  lime- 
stone, leaving  behind  the  more  resistant  siliceous  minerals.  These  soils  are 
remarkable  for  the  fact  that  they  contain  but  a  very  small  percentage  of  the 
original  limestone  rock,  the  larger  part  having  gone  into  solution.  It  has 
thus  required  the  solution  of  many  feet  of  rock  to  form  a  single  foot  of  soil. 
Thus  far  the  limestone  soils  east  of  Kansas  and  Texas  and  north  of  central 
Alabama  and  Georgia  have  been  grouped  in  two  important  series,  known  as 
the  Hagerstown  and  Clarksville. 

Clarksville  series.  Light  gray  to  brown  soils  with  yellow  to  red  subsoils, 
derived  mainly  from  the  St.  Louis  limestone.  While  not  as  strong  as  the 
Hagerstown  soils,  this  is  a  valuable  series.  Apples  and  peaches  are  commer- 
cially important.  Tobacco  is  a  leading  product.  General  farming  is  firmly 
established  in  many  extensive  regions. 

Cumberland  series.  Brown  surface  soils,  derived  from  thin  deposit  of 
sedimentary  material  overlying  residual  limestone  subsoils.  Used  for  cotton 
and  other  general  farm  crops,  truck  and  fruit. 

Decatur  series.  Reddish  brown  to  red  soils  with  intensely  red  subsoils. 
Intermediate  in  value  between  the  two  series  just  described.  Cotton,  corn, 
wheat,  oats,  forage  crops,  blue  grass,  and  peaches  are  the  leading  crops. 

Hagerstown  series.  Brown  to  yellowish  soils  with  yellow  to  reddish  sub- 
soils, derived  from  massive  limestone.  Among  the  most  productive  soils  of 
the  eastern  United  States.  Fine  wheat  and  general  farming  soils,  and  the 
seat  of  important  apple  orcharding  interests.  Blue  grass  is  indigenous. 

GLACIAL  AND  LOESSIAL  REGIONS 

The  soils  of  the  glaciated  part  of  the  country  constitute  one  of  the  most 
important  groups  in  the  United  States.  The  group  includes  all  soils  derived 


124  SCIENCE  AND    SOIL 

directly  from  till  or  loess.  The  soils  formed  from  the  till  are  confined  to  that 
part  of  the  country  lying  north  of  the  southern  limit  of  glacial  action,  but  the 
loess  soils  occur  also  south  of  this  line,  especially  along  the  Mississippi  and 
Ohio  rivers  and  in  Kansas  and  Nebraska.  The  line  of  the  southern  extension  of 
the  ice  sheet  touches  the  Atlantic  coast  about  New  York  City,  passes  through 
northern  New  Jersey,  southern  New  York,  and  northwestern  Pennsylvania, 
swings  southward  through  Ohio  to  Cincinnati,  crosses  the  Mississippi  River 
at  St.  Louis,  and  follows  the  south  side  of  the  Missouri  River  into  Montana, 
where  it  crosses  the  Canadian  boundary  line,  then  dips  southward  into  Idaho 
as  a  long  lobe  in  the  mountainous  nonagricultural  region,  and  crosses  the 
northwestern  part  of  Washington,  including  the  Puget  Sound  region. 

Practically  all  of  the  United  States  north  of  this  line  was  covered  in  recent 
geological  time  by  a  great  continental  glacier,  many  hundreds,  and  even  thou- 
sands, of  feet  in  thickness.  This  great  ice  sheet,  moving  in  a  southern  direction, 
filled  up  valleys,  planed  off  the  tops  of  hills  and  mountains,  ground  up  the 
underlying  rocks,  carried  the  derived  material  both  within  and  upon  the  ice, 
and  finally  deposited  the  gravel,  sand,  silt,  and  clay,  as  a  mantle,  varying  in 
thickness  from  a  few  feet  to  more  than  300  feet.  Often  this  material  has  been 
transported  hundreds  of  miles,  and  is  wholly  unrelated  to  the  underlying  rocks, 
but  in  some  places  the  movement  has  been  slight,  and  the  drift  consists  very 
largely  of  the  ground-up  underlying  rock.  Over  a  large  porportion  of  the 
area  covered  by  the  drift  and  also  along  the  Ohio  and  Mississippi  rivers  and 
in  Kansas  and  Nebraska,  the  surface  material  consists  of  a  fine  silty  deposit, 
known  geologically  as  "loess"  and  "Plains  marl."  In  the  classification  of  the 
glacial  soils,  three  important  series  —  Miami,  Marshall,  and  Volusia  —  having 
distinct  characteristics  have  been  recognized  and,  in  addition,  quite  a  number 
of  miscellaneous  soils  which  cannot  be  put  in  any  series. 

Marshall  series.  Dark -colored  upland  prairie  soils.  The  principal  soils 
of  the  great  corn  belt  belong  to  this  series,  while  in  the  Northwest  the  finest 
wheat  soils  are  found  in  this  group.  They  are  among  the  best  general  farming 
soils  of  the  entire  country. 

Miami  series.  Light-colored  upland  timbered  soils.  The  different  mem- 
bers of  this  series  are  considered  good  general  farming  soils  and  have  in  ad- 
dition special  adaptations  for  truck,  fruit,  small  fruit,  and  alfalfa. 

Volusia  series.  Light-colored  soils  with  yellowish  sut  soils,  derived  by  feeble 
glacial  action  from  sandstones  and  shales.  The  soils  of  this  series  are  adapted 
to  the  production  of  potatoes,  grass,  oats,  buckwheat,  and,  in  the  less  elevated 
positions,  to  corn. 

GLACIAL  LAKE  AND  RIVER  TERRACES 

Another  important  group  of  soils  occurs  in  the  glacial  region,  principally 
as  terraces  around  lakes,  or  along  streams,  or  as  deposits  in  areas  which  were 
formerly  covered  by  water.  At  the  close  of  the  glacial  epoch  the  lakes  in  this 
part  of  the  United  States  were  not  only  more  numerous,  but  the  waters  of  those 
which  remain  reached  a  higher  level  and  covered  areas  that  are  now  far  above 


SURVEYS   BY  THE   UNITED   STATES   BUREAU     125 

their  present  shore  lines.  In  some  cases  several  distinct  terraces,  each  one 
marked  by  an  old  shore  line,  are  easily  discernible,  and  represent  successive 
stages  in  the  lowering  of  the  water  level.  The  elevation  above  the  lake  varies 
from  a  few  feet  to  more  than  200  feet.  The  surface  of  each  terrace  is  usually 
rolling  to  level,  with  a  gradual  slope  toward  the  lake,  but  sometimes  areas 
of  a  rough  and  broken  character  occur.  The  streams  which  cross  these  terraces 
have  frequently,  by  their  cutting,  produced  deep,  steep-sided  valleys,  especially 
near  the  lakes. 

The  soils  of  this  group  vary  from  typical  beach  gravels  to  offshore  deposits 
of  heavy  clays.  The  material  from  which  they  are  derived  consists  of  glacial 
debris  reworked  and  redeposited  in  the  lakes  or  along  streams.  While  this 
glacial  material  is  made  up  of  rocks  of  widely  varying  origin,  a  large  proportion 
of  it  often  consists  of  the  country  rock.  In  the  eastern  part  of  the  Great  Lake 
region  the  percentage  of  sandstone  and  shale  fragments  is  usually  very  high, 
while  in  the  western  part  more  of  the  igneous  rocks  are  present.  This  fact, 
together  with  differences  in  drainage  conditions,  has  given  rise  to  several  series 
of  soils. 

Clyde  series.  Dark -colored  swamp  soils  formed  from  reworked  glacial 
material  deposited  in  glacial  lakes.  A  special  use  for  these  soils  is  the  pro- 
duction of  sugar  beets,  while  general  farm  crops,  truck  and  canru'ng  crops,  are 
grown  extensively. 

Dunkirk  series.  Light-colored  reworked  glacial  material  occurring  as 
terraces  around  lakes  and  along  streams.  Good  general  farming  soils  and 
especially  adapted  to  grapes  and  other  fruits. 

Fargo  series.  Black  calcareous  soils  rich  in  organic  matter  formed  by 
deposition  of  material  in  glacial  lakes.  This  is  the  most  important  group  of 
soils  in  the  Red  River  Valley,  and  includes  exceptional  soils  for  the  production 
of  wheat,  barley,  and  flax.  While  these  are  the  chief  crops  at  present,  the  soil 
adaptations  are  by  no  means  limited  to  small  grain  production.  Timothy  and 
vegetables  may  become  more  important  products  with  the  development  of 
markets. 

Hudson  series.  Light  brown  to  yellowish  brown  soils,  with  drab  to  yellow- 
ish subsoils. 

Merrimac  series.  Brown  terrace  soils  underlain  by  gravel,  formed  prin- 
cipally of  reworked  glaciated  crystalline  rocks.  Leachy  soils  of  low  general 
farming  value,  but  especially  adapted  to  trucking  and  apple  orcharding  in  some 
sections. 

Sioux  series.  Dark-colored  soils  resting  on  dark  or  light-colored  subsoils, 
with  gravel  beds  usually  within  3  feet  of  the  surface.  The  crops  produced  on 
soils  of  this  series  range  from  early  short-seasoned  truck  crops  through  special 
crops  like  alfalfa  and  sugar  beets  to  the  wide  variety  of  general  farm  crops 
produced  in  the  Central  West. 

Superior  series.  Gray  and  red  soils  with  red  subsoils,  formed  from  reworked 
glacial  material  deposited  in  glacial  lakes.  Not  extensively  developed,  but 
known  to  include  fine  types  for  clover,  timothy,  and  small  fruits. 


12(5  SCIENCE   AND   SOIL 

Vergennes  series.  Light-colored  soils,  with  gray  or  whitish  subsoils, 
derived  from  Champlain  clay,  or  lighter  deposits  over  these  clays.  This 
series  includes  the  best  hay  and  apple  soils  of  the  Champlain  Valley.  A  wide 
variety  of  tillage  crops  is  grown,  but  cultivation  of  the  heavier  members  of  the 
series  is  very  difficult. 

RESIDUAL  SOILS  OF  THE  WESTERN  PRAIRIE  REGION 

This  region  consists  of  the  nonglacial  part  of  the  prairie  plains  bounded 
on  the  north  by  the  Missouri  River,  the  southern  limit  of  glaciers,  and  extending 
southward  through  Texas  to  the  Rio  Grande.  On  the  west  it  merges  into  the 
Plateau  region  at  very  near  the  2ooo-foot  contour,  and  on  the  east  is  limited 
by  the  Gulf  Coastal  Plain  and  the  Ozark  Plateau.  Its  surface  is  gently  rolling, 
with  occasional  low  hills,  and  is  cut  by  numerous  stream  channels.  The 
rocks  are  of  Carboniferous  age,  and  consist  of  sandstones,  shales,  and  limestones 
more  or  less  interbedded.  These  rocks  give  rise  to  three  series  of  soils,  viz. 
Oswego,  Crawford,  and  Vernon,  together  with  a  number  of  miscellaneous  soils. 
In  Kansas  and  Texas  these  soils  are  in  some  instances  more  or  less  modified 
by  the  admixture  of  gravel  and  sand  from  Tertiary  deposits  brought  down 
from  the  higher  areas  farther  west  occupied  by  crystalline  rocks. 

Crawford  series.  Brown  soils  with  reddish  subsoils,  derived  from  lime- 
stones. The  soils  of  this  series  range  from  rough  areas  suited  mainly  for 
pastures  to  fertile  general  farming,  fruit  growing,  and  trucking  soils. 

Oswego  series.  Gray  or  brown  soils,  derived  from  sandstones  and  shales. 
The  lighter  members  of  this  series  are  adapted  to  corn,  oats,  potatoes,  truck, 
and  fruit ;  the  heavier  to  these  crops  and  wheat. 

Vernon  series.  Brown  to  red  soils  typical  of  the  Permian  formation.  Soils  of 
this  series  show  a  wide  adaptation  according  to  texture.  General  farm  crops, 
including  cotton,  corn,  wheat,  Kafir  corn,  and  sorghum  are  the  leading  prod- 
ucts. Small  fruit,  peaches,  and  truck  are  grown  to  some  extent  and  are 
capable  of  marked  extension. 

GREAT  BASIN 

With  the  exception  of  one  soil  type  recognized  in  the  Laramie  area,  Wyoming, 
the  soils  in  this  group,  so  far  as  mapped,  are  confined  to  the  Great  Interior 
Basin  region.  They  are  derived  from  a  great  variety  of  rocks,  and  consist 
of  colluvial  soil  of  the  mountain  slopes,  deep  lacustrine  and  shore  deposits  of 
the  Bonneville  period,  and  of  recent  stream-valley  sediments  and  river-delta 
deposits. 

When  not  situated  above  or  outside  the  limits  of  irrigation,  or  rendered 
unfit  for  cultivation  by  accumulation  of  alkali  or  seepage  waters,  they  are  of 
great  agricultural  importance,  and  are  devoted  mainly  to  the  production 
of  grains,  sugar  beets,  alfalfa,  stone  or  other  tree  fruits,  and  vegetables. 

Bingham  series.  Porous  dark  or  drab  colluvial  and  alluvial  soils  under- 
lain by  gravel  or  rock,  occupying  lower  mountain  slopes.  The  lighter  types 


SURVEYS   BY  THE   UNITED    STATES    BUREAU 


127 


when  irrigable  are  devoted  to  orchard  fruits,  the  heavier  types  to  alfalfa  and 
sugar  beets. 

Jordan  series.  Light  to  dark -colored  lacustrine  desposits.  These  soils 
are  utilized  principally  in  the  production  of  alfalfa,  sugar  beets,  truck  crops, 
and  grains  under  favorable  conditions  for  irrigation  and  drainage,  but  consider- 
able areas  covered  by  some  of  the  members  of  this  series  are  not  utilized  on 
account  of  the  accumulation  of  alkali,  poor  drainage,  or  because  of  their  drift- 
ing character. 

Malade  series.  Dark-colored  alluvial  soils  underlain  by  light-colored  sands, 
sandy  loams,  or  heavy  reddish  material.  These  soils  are  devoted  chiefly  to 
sugar  beets,  alfalfa,  grain,  and  some  orchard  fruits. 

Redfield  series.  Red  soils  consisting  of  colluvial  and  alluvial  materials 
derived  from  red  sandstones  and  other  rocks.  The  lighter  members  are 
adapted  to  the  production  of  alfalfa,  grain,  and  general  farm  crops  when 
irrigable  and  well  drained.  The  heavier  members,  as  far  as  encountered,  are 
poorly  drained  and  have  not  been  developed. 

Salt  Lake  series.  Dark-colored  soils  underlain  by  stratified  sediments  of 
lacustrine  origin.  These  soils,  as  far  as  encountered,  occupy  very  low,  flat 
positions  around  the  lake,  and  have  not  been  developed  to  any  extent. 

NORTHWESTERN  INTERMOUNTAIN  REGION 

The  most  extensive  and  uniform  soil  types  of  this  region  consist  of  residual 
materials  overlying  and  derived  from  extensive  basaltic  lava  plains  and  in 
some  cases  from  granite  rocks  or  of  ancient  lacustrine  sediments  or  extensive 
lake  beds  now  more  or  less  modified  by  erosion  or  aeolian  agencies.  Owing 
to  erosion  by  streams  and  to  movements  of  the  earth's  crust,  these  soils  now 
generally  occupy  more  or  less  elevated  sloping  or  rolling  plains.  About  the 
margins  of  the  lacustrine  or  residual  deposits  they  are  covered  by  sloping  plains 
and  fans  of  colluvial  wash  from  the  adjacent  mountain  borders,  while  in  the 
vicinity  of  the  larger  streams,  which  have  carved  and  terraced  the  lacustrine 
beds  and  residual  soils,  occur  other  series  of  recent  alluvial  stream  sediments 
derived  from  reworked  materials  of  the  lake  beds  or  from  the  weathered  prod- 
ucts of  the  mountains.  It  is  the  soils  of  this  region  that  constitute  a  large 
portion  of  the  great  grain -producing  lands  of  the  Northwest. 

Bridger  series.  Dark-colored  soils  with  sticky  yellow  subsoils,  of  colluvial 
and  alluvial  origin.  These  soils  generally  occupy  elevated  foot  slopes  or  sloping 
valley  plains  and  have  not  been  developed  to  a  great  extent.  They  are  most 
extensively  used  for  the  production  of  grain,  and,  when  irrigated,  are  utilized 
in  the  production  of  alfalfa  and  other  hay  crops  and,  under  favorable  climatic 
conditions,  are  adapted  to  fruits. 

Gallatin  series.  Light  to  dark-colored  soils  with  yellowish  to  dark  com- 
pact subsoils,  of  recent  alluvial  origin  from  basaltic  and  volcanic  rocks.  These 
soils  generally  occupy  low  positions,  very  frequently  poorly  drained,  often 
subject  to  overflow,  and  have  not  been  extensively  developed  for  agricultural 


128  SCIENCE   AND   SOIL 

purposes.    They  are  used  chiefly  for  grazing  and,  to  some  extent,  in  the  pro- 
duction of  hay,  grains,  and  in  some  sections  for  vegetables. 

Yakima  series.  Ash-gray  to  light  brown  soils  derived  principally  from 
ancient  lake  sediments  consisting  of  an  admixture  of  volcanic  dust  and  ba- 
saltic, andesitic,  and  granitic  materials.  Certain  members  of  this  series  have 
been  very  successfully  developed  for  hop  culture,  alfalfa,  grass,  grain,  and 
fruit,  while  other  members  of  the  series,  owing  to  their  elevated  position  and 
general  rough  character,  have  not  been  developed  at  all. 

ROCKY  MOUNTAIN  VALLEYS,  PLATEAUS,  AND  PLAINS 

The  soils  of  the  Rocky  Mountain  valleys,  plateaus,  and  plains  are  derived 
from  a  wide  range  of  igneous,  eruptive,  metamorphic,  and  sedimentary  rocks. 
The  plateau  and  plain  types  occupy  a  more  or  less  elevated  position,  and  have 
sloping,  undulating,  or  irregular  surface  features.  They  are  derived  from 
underlying  sedimentary  rocks  or  consist  of  the  remains  of  the  ancient  extensive 
mountain  foot-slope  material  or  of  alluvial  deposits  along  streams  trenching  and 
terracing  the  sedimentary  rocks  of  the  plateaus  and  plains.  The  mountain  slope 
and  intermountain  types  consist  of  residual  and  colluvial  deposits  or  of  ancient 
lacustrine  or  later  stream  sediments,  occupying  mountain  foot  slopes  and 
narrow  valleys. 

The  soils  of  the  mountain  slopes  are  usually  of  little  agricultural  value, 
owing  to  their  rough  surface,  elevated  position,  and  the  consequent  imprac- 
ticability of  irrigation.  Those  of  the  plateaus,  valleys,  and  plains  vary  widely 
in  economic  importance,  depending  largely  upon  climatic  features,  topography, 
position,  and  water  supply  for  irrigation.  They  range  from  grazing  lands 
of  nominal  value  to  soils  adapted  to  the  most  important  and  intensively  culti- 
vated fruit,  melon,  sugar  beet,  and  other  special  crops. 

Billings  series.  Compact  adobe-like  gray  to  dark  or  brown  soils  and  sub- 
soils, formed  mainly  by  reworking  of  sandstones  and  shales,  and  occupying  old 
elevated  stream  terraces.  This  is  an  important  series  adapted  to  alfalfa  and 
general  farm  crops  and  stock  raising ;  also  used  to  a  considerable  extent  in  the 
production  of  sugar  beets. 

Colorado  series.  Light  gray  to  reddish  brown  soils  and  subsoils,  derived 
from  colluvial  wash.  Where  irrigable,  these  soils  are  important  soils  in  the 
production  of  alfalfa,  sugar  beets,  melons,  and,  to  a  limited  extent,  fruits.  A 
number  of  the  soils  of  the  series,  however,  are  so  situated  as  not  to  be  suscep- 
tible to  irrigation,  and  have  not  been  developed  for  agricultural  purposes. 

Finney  series.  Brown  to  nearly  black  soils  derived  from  glacial  material 
underlain  by  lighter-colored  subsoils.  The  heavier  soils  may  be  dry  farmed 
to  advantage,  and  would  become  very  productive  with  irrigation.  The  lighter 
soils  have  a  broken  surface,  are  porous,  and  easily  drifted  by  the  wind.  They 
are  best  adapted  to  grazing. 

Fruita  series.  Reddish  brown  soils,  formed  by  reworking  of  sandstones 
and  shales,  occurring  as  stream  terraces.  When  well  drained  and  free  from 


SURVEYS   BY   THE   UNITED    STATES   BUREAU     129 

alkali,  the  members  of  this  series  are  admirably  adapted  to  the  production  of 
choice  fruits,  alfalfa,  sugar  beets,  grains,  and  truck  crops. 

Laramie  series.  Dark -colored  soils,  with  light-colored  gravelly  subsoils,  de- 
rived from  colluvial  mountain  wash.  These  soils  have  not  been  extensively 
developed,  owing  to  their  elevation,  and  are  used  principally  for  grazing  pur- 
poses. 

Laurel  series.  Light  gray  to  black  soils,  underlain  by  river  sands  or  gravels, 
occurring  in  flood  plains  along  streams.  Under  favorable  moisture  conditions, 
these  are  fertile  soils,  adapted  according  to  locality  to  corn,  alfalfa,  sugar  beets, 
and  truck  crops,  but  the  areas  are  often  subject  to  overflow,  and  in  some  cases 
cannot  be  drained. 

Mesa  series.  Light  gray  to  brown  soils  derived  from  old  flood-plain  de- 
posits, now  elevated  to  form  mesa  lands.  Where  these  soils  have  been  devel- 
oped and  are  susceptible  of  irrigation,  they  are  used  mainly  for  alfalfa  and 
sugar  beets.  One  member  of  the  series  has  been  quite  extensively  and  very 
successfully  used  for  the  production  of  apples  and  peaches. 

Morton  series.  Brown  residual  soils,  derived  from  sandstones  and  shales- 
The  soils  lie  in  the  semiarid  region,  and  give  good  yields  of  wheat,  flax,  oats,  and 
potatoes,  when  rainfall  is  sufficient. 

San  Luis  series.  Reddish  brown  gravelly  soils,  formed  from  lacustrine 
sediments  of  volcanic  rock  materials.  On  account  of  the  position  and  the 
danger  from  alkali,  these  soils  have  not  been  successfully  developed,  but  have 
been  used  mainly  for  pasturage  and  forage  crops. 

Wade  series.  Brown  to  dark  brown  alluvial  soils,  formed  by  reworking  of 
sandstones  and  shales.  Used  for  oats,  flax,  millet,  and  wheat. 

ARID  SOUTHWEST 

The  soils  of  the  arid  Southwest  are  mainly  of  colluvial,  alluvial,  and  lacus- 
trine origin.  They  occupy  mountain  foot  slopes,  alluvial  fans,  debris  aprons, 
or  sloping  plains  of  filled  valleys,  sloping  or  nearly  level  plains,  and  bottoms  of 
stream  valleys  or  sinks  and  drainage  basins.  The  principal  colluvial  soils  of 
this  region  are  also  common  to  the  Pacific  coast.  The  climate  of  the  arid 
Southwest  is  characterized  by  semitropical  desert  conditions,  and  where  the 
soils  are  not  capable  of  irrigation,  they  have  little  or  no  present  agricultural 
value. 

Gila  series.  Light  to  dark  brown  soils  of  flood-plain  alluvium,  underlain 
at  varying  depths  by  coarse  sands  and  gravels.  Under  favorable  irrigation  and 
drainage  conditions,  the  members  of  the  Gila  series  are  adapted  chiefly  to  the 
production  of  alfalfa,  potatoes,  truck,  and  root  crops. 

Imperial  series.  Light-colored  or  reddish  soils  formed  from  old  marine 
or  lacustrine  sediments  modified  by  more  recent  deposits,  and  underlain  to 
great  depths  by  heavy  material.  These  soils  are  particularly  adapted  to  alfalfa, 
sorghum,  and  other  forage  crops. 

India  series.   Light-colored  soils  usually  underlain  by  coarser  sands  and 


130  SCIENCE  AND   SOIL 

gravels,  formed  by  colluvial  and  alluvial  wash  from  granitic  rock,  mingled 
with  some  shale  and  sandstone.  These  soils  are  adapted  to  fruit,  truck  crops, 
sweet  potatoes,  melons,  and  alfalfa,  under  favorable  conditions  of  irrigation 
and  drainage. 

PACIFIC  COAST 

The  soils  of  the  Pacific  coast,  including  those  of  the  coastal  and  interior 
mountain  ranges,  foothills,  and  valleys,  have  been  classified  into  a  number 
of  series,  varying  in  field  characteristics,  topography,  origin  and  mode 
of  formation,  and  agricultural  importance.  They  range  from  residual  and 
colluvial  soils  of  the  mountain  sides,  foot  slopes,  and  foothills,  to  deep  and 
extensive  river  flood  plains  and  delta  sediments,  and  ancient  and  modern  shore 
and  marine  lacustrine  deposits.  While  some  of  these  series  are  confined  to  a 
single  coastal  or  interior  mountain  range  or  valley,  others  are  of  wider  range 
and  extend  over  several  different  physiographic  regions.  The  value  of  these 
soils  and  their  adaptation  to  crops  is  dependent  largely  upon  the  possibilities 
of  irrigation  and  upon  local  conditions  of  rainfall  and  temperature,  all  of 
which  are  to  great  extent  dependent  upon  topography.  They  range  in  agri- 
cultural importance  from  those  devoted  only  to  extensive  grain  farming  to 
the  most  valuable  and  intensively  cultivated  lands  devoted  to  citrus  and  decid- 
uous fruits,  vines,  small  fruits,  and  other  special  crops. 

Anderson  series.  Reddish  gray  or  light  red  alluvial  soils  occupying  prin- 
cipal valley  plains  and  the  bottoms  of  intermittent  streams.  Generally  gravelly. 
The  soils  of  this  series,  when  not  too  gravelly,  are  adapted  to  the  production  of 
peaches,  pears,  prunes,  and  small  fruits,  but  are,  in  so  far  as  mapped  at  present, 
inextensive  types  of  secondary  agricultural  importance. 

Fresno  series.  Light-colored  soils  with  light  gray,  ashy  subsoils,  and 
alkali -carbonate  hardpan,  derived  from  old  alluvial  wash.  Where  protected 
from  alkali  accumulations,  these  soils  have  been  very  successfully  used  for 
vineyards  and  raisin  grapes,  and  are  particularly  adapted  to  almonds,  peaches, 
and  apricots. 

Hanford  series.  Recent  alluvium  of  flood  or  delta  plains  derived  from  a 
variety  of  rocks.  The  light-textured  soils  are  light  in  color,  and  the  heavy  tex- 
tured soils  are  dark  in  color.  The  lighter  members  of  the  series  are  adapted 
to  the  same  class  of  fruits  and  raisin  grapes  as  the  Fresno  series.  The  heavier 
members  of  this  series,  however,  are  better  adapted  to  alfalfa,  sugar  beets, 
celery,  asparagus,  and  other  truck  crops. 

Maricopa  series.  Loose,  dark-colored  soils  derived  from  unassorted  col- 
luvial or  partially  assorted  alluvial  materials,  generally  derived  from  granitic 
or  volcanic  rocks.  There  are  two  heavy  members  of  this  series  upon  which 
alfalfa,  grain,  and  sugar  beets  are  important  crops.  The  lighter  members,  when 
occupying  positions  so  that  they  can  be  irrigated,  are  adapted  to  citrus  and 
deciduous  fruits ;  also  vines. 

Oxnard  series.  Dark-colored  alluvial  or  colluvial  soils  derived  from  higher 
lying  areas  of  sandstones  and  shales.  Members  of  this  series  are  used  to  a  very 


SURVEYS   BY  THE  UNITED   STATES   BUREAU     131 

large  extent  for  sugar  beets  and  lima  beans,  and,  where  irrigation  is  not  practi- 
cable, extensively  used  for  grain. 

Placentia  series.  Reddish  soils  derived  largely  from  the  weathering  of  allu- 
vial and  colluvial  deposits,  generally  underlain  by  heavy  compact  red  material 
with  an  impervious  adobe  structure.  Large  areas  of  these  soils  are  devoted  to 
dry  farming  of  grain,  and  occur  throughout  southern  California  and  in  some  of 
the  coastal  valleys,  viz.,  Bakersfield,  Salinas,  and  San  Jose*.  These  are  exten- 
sive areas  under  irrigation,  which  are  valuable  for  producing  both  deciduous 
and  citrus  fruits.  The  heavier  members  of  this  series  have  been  more  success- 
fully used  for  grain  production  in  southern  California.  They  seem  particularly 
well  adapted  to  English  walnuts  and  olives.  The  soils  are  usually  well  drained. 
The  English  walnut  does  not  thrive  on  poorly  drained  soils. 

Redding  series.  Ancient  alluvial  valley  deposits  of  red  and  deep  red  color, 
generally  gravelly.  Heavy  red  subsoils  with  hardpan.  The  soils  of  this 
series,  when  not  carrying  an  excess  of  cobbles  or  underlain  at  shallow  depths 
by  hardpan,  are  excellently  adapted  to  the  production  of  choice  peaches  and 
small  fruits. 

Sacramento  series.  Gray  alluvial  soils  consisting  of  recent  stream  sedi- 
ments. The  lighter  members  of  this  series  are  used  mainly  for  the  production 
of  prunes,  pears,  and  peaches.  The  members  of  the  series  having  a  medium 
texture  are  adapted  to  sugar  beets,  alfalfa,  and  prunes.  The  heavier  members 
are  at  present  poorly  drained,  and  have  not  been  highly  developed,  being  used 
mostly  for  grain  and  grazing. 

Salem  series.  Residual,  alluvial,  or  colluvial  soils,  either  red  or  .dark  in 
color,  derived  from  rocks  of  basaltic,  schistose,  crystalline,  or  arenaceous 
character.  These  soils,  so  far  as  they  have  been  encountered,  seem  particularly 
adapted  to  hops,  potatoes,  and  have  been  used  to  some  extent  for  apples, 
peaches,  and  grain.  They  have  not  been  very  highly  developed  in  the  areas 
in  which  they  have  been  encountered. 

San  Joaquin  series.  Compact  red  soils  and  subsoils  derived  from  old 
marine  sediments,  usually  underlain  by  red  hardpan.  These  soils  have  been 
used  almost  exclusively  for  dry  farming  to  grain  on  account  of  the  general 
occurrence  of  hardpan  and  very  stiff  and  impervious  subsoils.  Recently,  in 
the  Sacramento  area,  some  members  of  this  series  have  been  very  successfully 
used  for  the  production  of  the  Tokay  grape  and  strawberries. 

Sierra  series.  Light  gray  to  red  and  frequently  gravelly  soils,  often  under- 
lain by  red  adobe.  Members  of  this  series  constitute  some  of  the  most  valu- 
able deciduous  fruit  soils  of  the  foothills  in  northern  California. 

Sites  series.  Residual  and  colluvial  soils  of  reddish  gray  or  dark  brown  color, 
derived  from  sandstones,  shales,  conglomerates,  and  volcanic  or  altered  ma- 
terial occupying  low,  rolling  foothills  and  their  valley  slopes,  usually  underlain 
at  shallow  depths  by  sandstones,  conglomerates,  or  heavy  subsoils.  The  Sites 
loam  and  clay  loam  adobe  are  the  important  soils  of  this  series  and  are  pro- 
ductive, but,  owing  to  their  positions,  are  generally  unirrigable  and  adapted  to 
dry  farming  to  grains. 


132 


SCIENCE   AND    SOIL 


Stockton  series.  Brown  to  black  soils  with  heavy  yellow  subsoils,  derived 
from  old  alluvial  sediments.  These  soils  have  been  used  principally  for  the 
production  of  grain.  The  lighter  members  of  this  series  have  been  adapted 
to  fruit. 

Willow  series.  Brown  soils  consisting  of  wash  deposited  by  intermittent  foot- 
hill streams.  These  soils  have  been  used  almost  exclusively  for  dry  farming 
grain  crops.  Large  ranches  are  being  broken  up  and  brought  under  irrigation, 
and  alfalfa  and  sugar  beets  are  likely  to  prove  the  most  important  crops. 

The  following  additional  quotations  from  Bureau  of  Soils  Bulle- 
tin 55  will  serve  to  acquaint  the  student  with  the  general  charac- 
ter of  the  more  detailed  descriptions  which  are  given  of  the  soil 
types  singly  and  in  series: 

Leonardtown  loam1  (Maryland,  Virginia,  Kentucky,  —  196,834  acres). 
"The  Leonardtown  loam  is  a  valuable  upland  soil  of  Maryland  and  Virginia. 
The  surface  is  slightly  rolling,  the  drainage  in  most  areas  is  good,  and  altogether 
the  land  is  well  suited  to  general  farming.  The  soil  has  a  special  value  in  the 
production  of  wheat  and  grass." 

Marion  silt  loam  (Illinois,  Missouri,  —  695,040  acres).  "A  large  pro- 
portion of  southern  Illinois  is  occupied  by  Marion  silt  loam.  The  type  occupies 
level  prairie  land  and  is  characterized  by  hard  silty  clay  subsoil  locally  known  as 
'  hardpan. '  It  is  low  in  organic  matter,  and  this,  combined  with  the  impervious 
nature  of  the  subsoil,  causes  crops  to  suffer  in  wet  as  well  as  dry  seasons.  Wheat, 
corn,  and  grasses  are  the  principal  crops,  but  the  average  yields  are  considerably 
lower  than  upon  the  black  prairie  soils.  It  seems  especially  well  adapted  to 
apples,  and  many  large  orchards  have  been  planted.  Strawberries  also  do  well." 

Marshall  series  (glacial  and  loessial  regions).  "The  Marshall  series  in- 
cludes the  dark -colored  upland  glacial  and  loessial  soils,  which  cover  almost  all 
of  the  great  prairie  region  of  the  Central  West.  The  soils  of  this  series  are 
characterized  and  distinguished  from  those  of  the  Miami  series  by  the  relatively 
large  quantity  of  organic  matter  in  the  surface  soils,  which  gives  them  a  dark 
brown  to  black  color.  The  topography  is  level  to  rolling,  and  artificial  drainage 
is  necessary  on  many  level  and  low -lying  areas  to  secure  the  best  results.  The 
soils  of  this  series  are  very  productive  and  constitute  the  great  corn  soils  of  the 
country. 

"The  Marshall  silt  loam,  loam,  and  clay  loam  constitute  the  principal  soil 
types  throughout  the  great  corn  belt,  and  rank  among  the  most  productive  of 
our  general  farming  soils.  In  Iowa,  Illinois,  and  Nebraska,  corn,  oats,  clover, 
and  timothy  are  the  leading  crops,  while  in  Minnesota  and  the  Dakotas  wheat 
becomes  of  primary  importance.  The  Miami  (Marshall)  black  clay  loam,  when 
drained,  is  also  an  exceedingly  fertile  soil,  being  particularly  well  adapted 

1  The  Leonardtown  loam  and  Leonardtown  gravelly  loam  in  the  Norfolk,  Vir- 
ginia, report  are  the  Portsmouth  silt  loam. 


SURVEYS   BY   THE   UNITED   STATES   BUREAU 


1.33 


to  corn.  The  sandy  loam  and  fine  sandy  loam,  while  not  so  well  adapted  to 
general  farming  as  the  heavier  soils,  are  quite  productive  and  have  a  wide  crop 
adaptation.  The  sand  and  fine  sand  are  well  suited  to  truck  crops,  but  give 
rather  uncertain  yields  of  general  farm  crops. 

"The  acreage  of  the  types  so  far  encountered  is  as  follows : 


AREA  AND  DISTRIBUTION  OF  THE  SOILS  OF  THE  MARSHALL  SERIES 


SOIL  NAME 

STATES  IN  WHICH  EACH  TYPE  HAS  BEEN  FOUND 

TOTAL  AREA 
(Acres) 

Marshall  stony  loam 
Gravel  l   .     .     . 

North  Dakota,  South  Dakota       .... 
Minnesota,  North  Dakota  

84096 
2s6o 

Gravelly  loam   . 
Sand    .... 

Kansas,  Minnesota,  NorthDakota,  Wisconsin 
Indiana,  Iowa,  Wisconsin  

I068l6 
t?27'?6 

Fine  sand     .     . 

Indiana,  Iowa,  Minnesota,  Nebraska,  North 
Dakota    

C4272 

Sandy  loam  .     . 

Illinois,  Indiana,  Kansas,  Minnesota,  South 
Dakota     

26l44O 

Fine  sandy  loam 

Indiana,  Minnesota,  Nebraska,  North  Da- 
kota       •  

IIIl68 

Loam  .... 

Illinois,  Indiana,  Iowa,  Michigan,  Minnesota, 
Nebraska,  North  Dakota,  South  Dakota, 
Wisconsin     

l68o8?2 

Silt  loam  2     .     . 

Colorado,  Illinois,  Indiana,  Iowa,  Kansas, 
Louisiana,  Minnesota,  Missouri,  Nebraska, 
North  Dakota,  Wisconsin   

44^4470 

Clay  loam     .     . 
Black  clay  loam  3 

Clay    .... 

Iowa,  Minnesota,  North  Dakota,  Wisconsin 
Illinois,  Indiana,  Iowa,  Michigan,  Minnesota, 
North  Dakota,  Ohio,  South  Dakota,  Wis- 
consin            
North  Dakota  

600320 

572176 
76800 

Total   .     .     . 

8057686 

1  The  soil  mapped  as  Marshall  gravel  in  Pontiac  area,  Michigan,  is  Miami 
gravelly  sand. 

2  Mapped  as  Miami  silt  loam  in  Clinton  and  St.  Clair  counties,  Illinois,  and  as 
Fresno  fine  sandy  loam  in  Lower  Arkansas  Valley  area,  Colorado. 

3  The  soil  mapped  as  Miami  (now  Marshall)  black  clay  loam  in  the  Toledo  area, 
Ohio,  is  Clyde  clay. 

Miami  series  (glacial  and  loessial  regions).  "The  Miami  series  is  one 
of  the  most  important,  widely  distributed,  and  complete  soil  series  that  has 
been  established.  The  series  is  characterized  by  the  light  color  of  the  surface 
soils,  by  derivation  from  glacial  material,  and  by  being  timbered  either  now 
or  originally.  The  heavier  members  of  the  series  are  better  adapted  to  wheat 


134  SCIENCE  AND   SOIL 

AREA  AND  DISTRIBUTION  OF  THE  SOILS  OF  THE  MIAMI  SERIES 


Son.  NAME 

STATES  IN  WHICH  EACH  TYPE  HAS  BEEN  FOUND 

TOTAL  AREA 

Miami  stony  sand  . 

Michigan,  New  York,  Washington,  Wiscon- 
sin      

100278 

Stony  sandy  loam 

New  York,  Rhode  Island,  Vermont,  Wash- 
ington      

267^28 

Stony  loam     .     . 
Gravel  .... 

Michigan,  Minnesota,  New  York,  Ohio, 
Rhode  Island,  Washington,  Wisconsin 
Illinois,  Wisconsin        

879094 
21^76 

Gravelly  sand  i   . 

QI242 

Gravellysandy  loam 

Indiana,  Michigan,  Minnesota,  Washing- 
ton      

58624 

Gravelly  loam  2  . 
Sand      .... 

Fine  sand  .     .     . 

Indiana,  Michigan,  Ohio      
Indiana,    Kansas,    Michigan,   Minnesota, 
Nebraska,  Ohio,  Wisconsin    .... 
Illinois,  Indiana,  Iowa,  Kansas,  Michigan, 
Minnesota,   Missouri,   Nebraska,   New 
York,  Wisconsin  

71232 
795720 

263<64 

Sandy  loam  3 

Fine  sandy  loam  4 
Loam  5  .     .     .     . 
Silt  loam  8       .     . 

Indiana,  Iowa,  Michigan,  Minnesota,  Ohio, 
Washington,  Wisconsin     
Indiana,  Michigan,  New  York    .... 
Indiana,  Michigan,  Wisconsin   .... 
Illinois,   Indiana,   Iowa,   Kentucky,   Mis- 
souri, Nebraska,  Rhode  Island,  Wiscon- 
sin      

745460 

130816 
214720 

IQCI488 

Clay  loam  7     .     . 

Indiana,  Iowa,  Michigan,  Ohio,  Washing- 
ton, Wisconsin      

1831818 

Total      .     .     . 

7422760 

1  Mapped  as  Marshall  gravel  in  Pontiac  area,  Michigan. 

2  The  soil  mapped  as  Miami  gravelly  loam  in  the  Big  Flats  area  and  Syracuse 
area,  New  York,  is  the  Dunkirk  gravelly  loam. 

3  The  soil  mapped  as  Miami  sandy  loam  in  the  Grand  Forks  area,  North  Dakota, 
is  the  Clyde  fine  sandy  loam;   in  the  Montgomery  County  area,  Ohio,  is  Wabash 
sandy  loam;    and  in  Posey  County  area,  Indiana,  is  Wabash  fine  sandy  loam. 

4  The  soil  mapped  as  Miami  fine  sandy  loam  in  Posey  County,  Indiana,  and  Union 
County,  Kentucky,  is  Waverly  fine  sandy  loam;  in  the  Boonville  area,  Indiana,  is  the 
Norfolk  fine  sandy  loam ;  in  the  Lyons  and  Syracuse  areas,  New  York,  is  Dunkirk 
fine  sandy  loam;  and  in  St.  Claire  County,  Illinois,  is  Memphis  silt  loam. 

5  The  Miami  loam  in  the  Auburn,  Lyons,  and  Syracuse  areas,  New  York;   the 
Columbus,  Coshocton,  Montgomery,  Toledo,  and  Westerville  areas,  Ohio;  the  Fargo 
and  Grand  Forks  areas,  North  Dakota;    the  Marshall,  Minnesota,  and  Pontiac 
areas,  Michigan;    and  the  Viroqua  area,  Wisconsin,  is  Wabash  loam.     The  soil 
mapped   as  Miami   loam   in  Tazewell   County,  Illinois,  is   Sioux   loam,  and  that 
mapped  as  Miami  loam  in  the  Janesville  area,  Wisconsin,  is  the  Sioux  sandy  loam. 

8  The  soil  mapped  as  Miami  silt  loam  in  the  Syracuse  area,  New  York,  is  Dunkirk 


SURVEYS   BY   THE   UNITED   STATES   BUREAU     135 

than  the  corresponding  members  of  the  Marshall  series,  but  they  do  not  pro- 
duce as  large  yields  of  corn. 

"The  clay  loam  is  the  most  important  for  general  farming,  and  forms  the 
principal  type  of  soil  in  western  Ohio  and  central  and  eastern  Indiana.  It  is 
especially  well  adapted  to  small  grain  and  grass  crops.  The  silt  loam  is  more 
rolling  and  hilly  than  the  clay  loam  and  is  not  so  well  suited  to  general 
farming.  Wheat  does  better  upon  it  than  upon  the  Marshall  silt  loam,  with 
which  it  is  closely  associated,  but  the  yields  of  corn  are  considerably  less. 
It  is  also  well  adapted  to  fruit,  especially  apples.  The  sandy  loam  and  fine 
sandy  loam  are  used  for  general  agriculture,  but  are  especially  adapted  to  me- 
dium and  late  truck  crops  and  fruit.  The  loam  is  suited  to  corn  and  potatoes, 
while  small  grain  and  grass  are  grown,  but  with  less  success  than  upon  the  clay 
loam.  Strawberries  and  raspberries,  as  well  as  other  small  fruits,  do  well  on 
this  type.  The  stony  sand,  gravelly  sand,  and  gravel  are  not  of  much  agricul- 
tural value  under  present  conditions.  The  stony  loam  is  a  good  general  farm- 
ing soil,  is  also  well  adapted  to  apples,  and  furnishes  excellent  pasture,  while 
in  New  York  alfalfa  is  grown  upon  it  very  successfully.  The  stony  sandy 
loam  and  gravelly  sandy  loam  are  not  strong  soils,  but  are  fairly  well  suited 
to  light  farming,  fruit,  and  truck.  The  sand  and  fine  sand  are  not  adapted 
to  general  farming,  but  are  the  best  early  truck  soils  of  this  section. 

"The  acreage  of  the  different  types  so  far  encountered  is  shown  in  the 
preceding  table." 

silt  loam,  and  that  mapped  as  Miami  silt  loam  in  Clinton  and  St.  Claire  counties, 
Illinois,  is  Marshall  silt  loam. 

7  The  soil  mapped  as  Miami  clay  loam  in  Toledo  area,  Ohio,  is  Dunkirk  clay 
loam,  and  that  mapped  as  Miami  clay  loam  in  the  Stuttgart  area,  Arkansas,  is 
Crowley  silt  loam. 


CHAPTER  IX 

SOIL  ANALYSIS  BY  THE   UNITED   STATES  BUREAU  OF  SOILS 

THE  United  States  Bureau  of  Soils  Bulletin  54  (December, 
1908),  on  "  The  Mineral  Composition  of  Soil  Particles,"  contains 
data  from  which  can  be  computed  1  accurately  the  total  amounts 
of  phosphorus,  potassium,  magnesium,  and  calcium,  in  the  ignited 
surface  soil  of  twenty-seven  important  soil  types  of  the  United 
States.  The  loss  on  ignition  of  ordinary  soils  usually  approaches 
10  per  cent,  and  includes  chiefly  the  combined  water,  organic 
matter,  and  more  or  less  carbon  dioxid,  if  carbonates  are  present; 
consequently,  the  results  given  on  the  basis  of  ignited  soil  are,  as  a 
rule,  about  one  tenth  higher  than  if  given  on  the  usual  basis  of 
dry  soil. 

The  following  general  statements  regarding  these  soil  samples 
are  made  by  the  Bureau  of  Soils  (Bulletin  54,  page  15) : 

"Our  extensive  collection  of  soils  from  important  and  well-marked  soil 
types  enables  us  to  select  samples  fully  representative  of  the  soils  of  the  country. 
Accordingly,  agricultural  soils  of  known  character  were  selected  so  as  to  include 
those  from  various  geographical  sections  and  from  a  number  of  soil  provinces. 
Thus  we  have  taken  soils  from  the  Coastal  Plains,  the  Piedmont  region, 
glacial  soils,  nonglacial  soils  of  the  interior,  and  those  of  the  arid  region,  the  list 
comprising  27  soil  types." 

"  We  have  but  two  soils  of  the  arid  region  to  compare  with  the  twenty-five 
of  the  humid  region.  The  latter  were  collected  to  represent  soils  of  all  classes 
—  those  of  low,  of  medium,  and  of  high  productivity;  sandy  soils,  clay  soils, 
calcareous  soils,  and  those  intermediate  between  these  extremes.  They  may 
be  taken  as  fairly  well  representing  the  humid  soils.  The  two  arid  soils  cannot 
be  considered  to  represent  so  well  those  of  the  region  because  of  their  limited 
number  and  similarity  of  texture,  both  being  fine  sandy  loams." 

"The  Coastal  Plains  soils  have  resulted,  to  a  large  extent,  from  material 
washed  from  the  Piedmont  Plateau  and  deposited  in  water  at  lower  levels. 

1  The  Bureau  of  Soils  Report  shows,  for  example  (Bulletin  54,  page  19),  that 
Leonardtown  loam  contains  29.5  per  cent  of  sand,  55  per  cent  of  silt,  and  15  per 
cent  of  clay,  and  that  the  total  P^Os  which  these  particles  contain  is  .01  per  cent 
in  the  sand,  .02  per  cent  in  the  silt,  and  .03  per  cent  in  the  clay. 

136 


ANALYSIS   BY   THE   UNITED    STATES   BUREAU 

They  have  suffered  from  decomposition  and  solution  more  than  have  the 
Piedmont  and  Appalachian  soils,  and  there  has  often  been  a  greater  separation 
of  the  finer  from  the  coarser  particles. " 

"The  tables  show  that  the  residual  soils,  Chester  mica  loam,  Porter's  black 
loam,  and  Cecil  clay,  contain  more  plant-food  constituents  than  do  the  Coastal 
Plains  soils.  This  is  especially  true  of  the  phosphorus,  the  potassium,  and  the 
magnesium." 

"The  sandy  and  the  silty  glacial  soils  are  somewhat  similar  in  percentage 
composition.  Owing  to  the  latter  consisting  to  so  large  an  extent  of  such  fine 
particles,  it  might  have  been  supposed  that  decomposition  and  leaching  would 
have  affected  them  more  .  .  .  but  the  silty  soils  are  loessial  for  the  most  part, 
and  were  formed  from  material  blown  by  winds  from  glaciated  areas  and 
deposited  where  now  found,  or  of  material  that  has  since  been  reworked  by 
water.  Minerals  rich  in  alkalis  and  alkaline  earths,  being  relatively  easily 
crushed,  would  form  a  larger  percentage  of  these  silty  soils  than  they  do  of  the 
original  glacial  soils ;  so  that  even  if  there  has  been  a  tendency  to  impoverish 
them  by  leaching,  their  originally  greater  richness  enables  the  loessial  soils 
to  compare  well  with  those  strictly  glacial." 

In  Table  22  are  reported  the  total  amounts  of  phosphorus,  po- 
tassium, magnesium,  and  calcium  found  by  the  Bureau  of  Soils  in 
2  million  pounds  of  ignited  soil  for  the  surface  soil  of  each  of  the 
27  type  soils,  and  also  the  amounts  in  the  acid-soluble  portion  of 
one  subsoil,  or  underlying  greensand  marl. 

While  these  soils  "  were  selected  to  represent  all  classes  —  those 
of  low,  of  medium,  and  of  high  productivity,"  Bulletin  54  gives  no 
information  as  to  the  agricultural  value  of  the  different  soils. 
Fortunately,  the  Annual  Reports  of  the  Bureau  of  Soils  contain  the 
descriptions  made  by  the  soil  survey  men  concerning  the  common 
crops  and  normal  crop  yields  produced  on  each  of  these  soils,  and 
thus  a  correlation  is  made  possible  between  chemical  composition 
(as  recently  determined  by  actual  ultimate  analysis)  and  produc- 
tive capacity,  of  these  important  and  extensive  types  of  soil  (as 
reported  in  previous  years  from  field  investigations).  Even  here 
the  student  is  advised  not  to  accept  opinions  expressed,  predictions 
made,  or  conclusions  drawn,  unless  clearly  supported  by  chemical 
facts  or  by  long-continued  agricultural  experience. 

In  each  of  the  following  descriptions  the  first  paragraph  is  quoted 
from  Bureau  of  Soils  Bulletin  54  (December,  1908),  and  the 
second  paragraph  is  quoted  from  the  Annual  Report  of  the  "  Field 


138 


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ANALYSIS   BY  THE   UNITED   STATES   BUREAU     139 

Operations  of  the  Bureau  of  Soils  "  for  the  year  designated.  For 
convenient  reference,  the  number  of  pounds  of  phosphorus  shown 
in  Table  22  is  given  at  the  beginning  of  the  second  paragraph  in 
each  description,  not  that  the  supply  of  the  one  element  always 
correlates  with  productive  power,  but  because  it  does  so  more 
frequently  than  any  other. 

SOILS  OF  THE  ARID  REGION 

Fresno  fine  sandy  loam  (California)  "is  composed  largely  of  silt  to  fine 
sand.  It  is  locally  known  as  'white-ash  land,'  from  its  color  and  its  physical 
character.  The  soil  has  probably  been  derived  from  volanic  ash,  but  light- 
colored  loams  and  sands  have  also  contributed  to  it.  The  soil  lies  flat  and 
works  well,  unless  it  be  puddled,  when  water  penetrates  it  slowly  and  hard 
clods  or  lumps  form  on  drying.  The  lower  subsoil  is  heavier,  a  blue  clay 
being  encountered  at  the  depth  of  a  few  feet.  Because  of  the  poor  drainage 
or  light  rainfall,  this  soil  generally  contains  alkali. " 

(1830  Ib.  P.)  "Was  originally  considered  extremely  productive,  and  is  now, 
where  the  drainage  is  good.  Some  of  the  first  colonists  settled  on  this  land 
through  choice. "  (Report  for  1900,  page  46.) 

India  fine  sandy  loam  (California)  "is  made  up  of  clay,  silt,  and  the  fine 
grades  of  sand.  The  clay  is  so  flocculated  that  the  soil  in  its  field  condition 
is  lighter  than  the  mechanical  composition  would  indicate.  The  soil  was  mainly 
formed  by  erosion  from  adjacent  mountains,  the  material  being  deposited 
in  a  bay  or  arm  of  the  sea,  but  it  has  been  greatly  modified  by  wind  action. 
It  contains  micaceous  grains  and  minute  shells.  The  soil  ranges  in  depth  from 
2\  to  5  feet  and  is  underlain  with  sandy  loam  or  sand.  The  surface  usually 
has  a  uniform  slope  and  is  generally  well  drained,  but  its  high  capillary  power 
draws  much  water  to  the  surface,  causing  an  accumulation  of  alkali  by  its 
evaporation.  In  the  lower  levels  the  alkali  is  present  in  injurious  amounts. 
Owing  to  insufficient  rainfall,  the  salts  are  not  washed  out  of  this  soil  so  well  as 
might  be  expected  from  its  physical  character. " 

(2090  Ib.  P.)  "Where  not  too  strongly  alkaline,  it  will  produce  in  abundance 
any  of  the  crops  suited  to  the  climate."  (Report  for  1903,  page  1255.) 

COASTAL  PLAINS  SOILS 

Leonardtown  loam  (Maryland)  "consists  of  a  yellow  silty  loam,  fine  and 
powdery  when  dry,  but  puddling  to  a  plastic  mass  when  thoroughly  wet. 
The  subsoil  consists  of  a  brittle  mass  of  interlocking  clay  lenses,  lumps,  and 
fragments,  separated  by  seams  and  pockets  of  medium  to  fine  sand.  This 
subsoil  is  as  impervious  as  clay,  owing  to  its  peculiar  shingle-like  structure.  It 
is  an  upland  soil,  and  is  generally  slightly  rolling. " 

(160  Ib.  P.)    "Covers  about  41  per  cent  of  St.  Mary  County.  .  .  .   This 


140 


SCIENCE  AND    SOIL 


soil  has  been  cultivated  for  upward  of  two  hundred  years,  but  it  is  now  little 
valued  and  is  covered  with  oak  and  pine  over  much  of  its  area.  It  is  worth 
from  $i  to  $3  an  acre.  The  cultivated  areas  produce  small  crops  of  corn, 
wheat,  and  an  inferior  grade  of  tobacco." 

To  this  statement  of  facts  is  added  the  opinion  that  "  the 
generally  low  estimation  in  which  land  is  held  is  probably  wholly 
unjustified.  ...  In  texture,  in  chemical  composition,1  and  in 
general  agricultural  value  (when  carefully  and  intelligently 
farmed)  these  lands  compare  favorably  with  the  Hagerstown  loam 
of  western  Maryland  and  Lancaster  County,  Pa.,  which  are  con- 
sidered the  most  valuable  soils  of  the  Atlantic  States  for  general 
farm  crops."  (Report  for  1900,  page  33.) 

The  Bureau  of  Soils  also  reports  that  45,770  acres  of  this  type  of 
soil  are  found  in  Prince  George  County,  which  borders  the  District 
of  Columbia  on  the  east  and  south,  concerning  which  the  Bureau's 
Report  for  1901  contains  the  following  statements: 

"The  soil  is  not  adapted  to  tobacco,  and  has  consequently  been  allowed 
to  grow  up  to  scrub  forests,  so  that  large  portions  of  it  are  at  present  uncleared. 
Such  unimproved  lands  can  be  bought  for  $1.50  to  $5.00  an  acre,  even  within  a 
few  miles  of  the  District  line.  The  soil  has  been  badly  neglected,  and,  when 
cultivated,  the  methods  have  not  been  such  as  to  promote  fertility.  It  is  fre- 
quently acid,  and  needs  lime  and  manure,  or  green  crops  turned  under.  When 
properly  handled,  as  it  is  in  a  few  places,  good  yields  of  wheat,  corn,  and  grass 
are  obtained." 

And  to  this  statement  of  facts  is  also  added  the  opinion  that 
"  upon  the  whole  it  is  one  of  the  most  promising  soils  2  of  the  local- 

1  See  Table  22  for  chemical  composition  of   the  Leonardtown  loam  and  the 
loam  and  clay  of  the  Hagerstown  series.  —  C.  G.  H. 

2  Determinations  of  the  water-soluble  constituents  in  36  samples  of  Leonardtown 
loam  are  included  in  the  data  which  led  Whitney  and  Cameron  to  draw  the  very 
erroneous  conclusions  that  "practically  all  soils  contain  sufficient  plant  food  for 
good  crop  yields,  that  this  supply  will  be  indefinitely  maintained,  and  that  the 
actual  yield  of  plants  adapted  to  the  soil  depends  mainly,  under  favorable  climatic 
conditions,  upon  the  cultural  methods  and  suitable  crop  rotations."  (Bureau  of 
Soils  Bulletin  22,  page  64.) 

The  following  quotations  are  taken  from  page  34  of  Bureau  of  Soils  Bulletin  22 
(1903).  They  furnish  some  information  as  to  what  is  done  when  this  soil  is  "properly 
handled": 

"There  is  no  apparent  relation  between  the  yield  of  crops  and  the  soluble  salt 
content  of  soils,  even  where  the  yields  per  acre  differ  as  much  as  from  4  bushels  to 
25  or  30  bushels. 


ANALYSIS   BY  THE   UNITED   STATES    BUREAU     141 


ity,  although  it  is  not  so  considered  by  the  resident  farmers." 
(Report  for  1901,  page  45.) 

Norfolk  sand  (Maryland)  "is  a  coarse  to  medium  orange  or  yellow  sand, 
having  a  depth  of  about  10  inches.  The  subsoil  is  coarse  to  medium,  becom- 

"  As  bearing  upon  this  point  of  the  association  or  nonassociation  of  high  analyti- 
cal figures  with  large  crop  yields,  no  more  striking  evidence  occurs  to  us  than  the 
following  letter  written  by  Mr.  Taylor,  May  26,  while  in  the  field  in  St.  Mary  County, 
Md.,  and  forming  a  part  of  his  regular  reports  to  the  Bureau  at  Washington: 

"'At  Park  Hall,  upon  the  farm  of  Mr.  S — ,  who  is  recognized  as  one  of  the 
best  farmers  of  the  community,  I  secured  some  samples  of  the  Leonardtown  loam 
from  a  wheat  field  which  will  produce  from  30  to  35  bushels  per  acre  this  season. 
The  land  was  in  tobacco  last  season,  upon  which  barnyard  manure  and  400  pounds 
of  fertilizer  had  been  used.  Nothing  was  added  when  the  wheat  was  sown. 
The  land  was  plowed  about  8  inches  deep.  The  soil  lacked  the  usual  grayish, 
ashy  appearance  of  the  Leonardtown  loam,  and,  owing  to  cultivation,  was  loose 
and  mellow  to  a  depth  of  over  two  feet.  One  of  these  samples  was  compared  with 
one  taken  from  another  wheat  field  upon  the  same  type,  where  the  yield  would  not 
be  over  6  or  8  bushels.  This  latter  land  was  farmed  by  negroes,  was  in  wheat 
last  year,  and  produced  a  fair  crop,  so  it  is  said.  No  manure  but  a  little  guano 
was  used  last  fall.  The  ground  was  uneven  on  the  surface,  and  below  the  first  4 
or  5  inches  the  soil  was  hard  and  compact.  A  comparison  of  the  analyses  is  given 
below : 

PARTS  PER  MILLION  OF  OVEN-DRIED  SOIL 


CONDITION 

PER  CENT 

OF 

MOISTURE 

PHOSPHORIC 
ACID 
(P04) 

NITRIC 
ACID 
(NO,,) 

CALCIUM 

(Ca) 

POTAS- 
SIUM 
(K) 

Good  wheat  : 
First  foot      

14.2 

2.0O 

13.22 

14.72 

24.36 

Second  foot  

10.  0 

3.72 

IO.QI 

12.  <2 

24.80 

Poor  wheat  : 
First  foot      

14.7 

4-72 

1C.  -24 

7.01 

3^.40 

Second  foot  

IQ  Q 

4  14. 

II.  l6 

4.1^ 

r  30.38 

. 


It  will  be  noted  that  the  poor  soil  shows  more  water-soluble  plant  food  with  all 
elements  except  calcium.  Other  data  reported  show  that  the  pounds  of  water- 
soluble  calcium  per  million  pounds  of  oven-dried  soil  of  the  Leonardtown  loam 
varied  from  2.66  to  29.52  in  the  first  two  feet  where  the  soil  was  in  "good  condition," 
and  from  3.95  to  24.99  where  the  soil  was  in  "poor  condition. " 

It  appears,  however,  that  the  conclusions  of  Whitney  and  Cameron  even  con- 
cerning the  nonrelationship  between  crop  yields  and  water-soluble  plant  food  are 
wrong.  Professor  F.  H.  King,  a  most  careful  investigator  of  the  highest  integrity, 
as  the  result  of  two  years'  experiments,  including  many  determinations  made  during 
the  crop  season,  before  severing  his  connection  with  the  Bureau  of  Soils,  was  led 
to  the  following  conclusions: 


142 


SCIENCE   AND   SOIL 


ing  loamy  at  about  3  feet.    It  is  a  common  type  of  soil  in  the  Atlantic  and 
Gulf  Coastal  plains.    The  surface  is  level  to  rolling,  and  the  soil  is  well  drained." 

"Our  own  observations,  published  by  the  Bureau  of  Soils  (Bulletin  No.  26), 
have  demonstrated  that  four  good  soils,  observed  to  produce  two  and  a  half  times 
the  yield  per  acre  of  corn  and  potatoes  that  four  poorer  soils  did  under  identical 
treatment,  also  gave  up,  when  washed  three  minutes  in  five  times  their  weight  of 
pure  water,  2.58  times  as  much  plant  food.  Not  only  was  there  this  difference  in  the 
amount  of  plant  food  carried  in  water-soluble  form  in  the  best  and  in  the  poorer 
soils,  but  the  amounts  of  this  same  plant  food  taken  out  of  like  areas  of  field  by  like 
numbers  and  like  kinds  of  plants  during  the  same  time  was  3.2  times  as  great  in  the 
sap  of  the  plants  which  gave  the  highest  yields."  (Proceedings  Jamestown  Con- 
gress of  Horticulture,  1907,  page  n.) 

The  following  tabular  statement  is  a  summary  of  Professor  King's  data  secured 
under  known  conditions  from  the  eight  soils  mentioned.  (See  Bureau  of  Soils 
Bulletin  26,  page  120.)  It  should  be  stated  that  each  value  recorded  for  plant 
food  determined  is  the  average  of  28  different  determinations.  These  data  are 
certainly  far  more  trustworthy  than  the  selected  results  from  such  miscellaneous 
samples  as  are  referred  to  by  Professor  Whitney  in  Bulletin  22  (see  above  quotation). 

AVERAGE  CROP  YIELDS  AND  MEAN  AMOUNT  OF  WATER-SOLUBLE  PLANT 

FOOD  IN  FOUR  POOR  SOILS  AND  FOUR  GOOD  SOILS  FOR  THE 

SEASON  OF  1903.  —  By  F.  H.  King 


POOR  SOILS 


STATE    .... 

North 
Carolina 

Maryland 

Pennsylvania 

Wisconsin 

Son,  TYPE  .    .    . 

Norfolk 
Sandy  Soil 

Selina 
Silt  Loam 

Norfolk  Sand 

Sassafras 
Sandy  Loam 

8,^ 

rt  !s 

fc8 

h 

Average  of 
4  Good  Soils 

Hagerstown 
Clay  Loam 

2  8 

•2  § 

w 

Janesville 
Loam 

1 

GOOD  SOILS 


CROP  YIELDS  PER  ACRE:  AVERAGE  OF  FIVE  PLOTS  FOR  EACH  SOIL 


Corn,  bu.      .     .     . 
Potatoes,  bu.    .     . 

36.3 
47-7 

38.9 
70.4 

29.6 
102.7 

29-5 
93-4 

33-6 
78.6 

64-3 
213.2 

52-9 
168.0 

54-7 
iS7-o 

80.4 
290.5 

69-3 

237.1 

POUNDS   OF  WATER-SOLUBLE   PLANT-FOOD    ELEMENTS    IN    4   MILLION 
POUNDS  OF  SOIL:   AVERAGE  OF  28  DETERMINATIONS  FOR  EACH  SOIL 


Nitrogen      .     .     . 

8-3 

6.0 

8.1 

7-7 

7-5 

21.3 

15.0 

23-7 

34-6 

11.9 

Phosphorus       .     . 

10.4 

10.8 

15.2 

11.9 

12.  1 

22.2 

I8.3 

15-6 

30.0 

24.7 

Potassium    .     .     . 

47-5 

42.7 

46.5 

47.1 

46.0 

69-3 

48.9 

60.4 

99.9 

68.0 

Magnesium       .     . 

44-7 

45-i 

42.2 

47-5 

44-9 

9I.I 

78.0 

69.1 

115.2 

IO2.I 

Calcium  .... 

91.6 

114.9 

94-5 

TOO.  8 

100.5 

264.8 

264.4 

223.4 

293.6 

277.7 

Sulfur      .... 

62.3 

71.9 

50.2 

83.1 

66.9 

156.9 

121.  6 

104.9 

217.9 

l83.I 

ANALYSIS   BY   THE   UNITED   STATES   BUREAU     143 

(520  Ib.  P.)  "  Very  poorly  adapted  to  general  farm  crops,  and  little  success 
is  attained  with  either  corn  or  wheat,  and  none  of  the  grasses  do  well. "  (Report 
for  1901,  page  46.) 

Norfolk  loam  (Maryland)  "is  a  mellow  brown  sandy  loam  to  a  depth  of  about 

9  inches.    The  subsoil  to  36  inches  is  a  medium  to  heavy  loam,  which  is  often 
underlain  by  fine  yellow  sand.    In    the   area  from  which  the  samples  were 
taken  it  has  a  slight  elevation  and  is  gently  rolling.    It  is  usually  well  drained. " 

(610  Ib.  P.)  "The  principal  crop  grown  is  wheat,  which  yields  20  to  30 
bushels  per  acre  on  the  heaviest  phase  of  the  type  in  fair  seasons  and  from  15 
to  20  bushels  on  the  lighter  areas,  these  yields  depending  largely  on  the  amount 
of  fertilizer  used.  ...  It  responds  readily  to  applications  of  fertilizer  and 
lime."  (Report  for  1903,  page  172.) 

Orangeburg  sandy  loam  (Alabama),  "locally  called  'red  lands,'  is  a  brown 
to  a  reddish  brown  light  sandy  loam,  4  to  15  inches  deep,  resting  on  a  friable 
brick -red  sandy  clay  subsoil.  The  surface  is  rolling.  It  is  generally  well 
drained,  although  there  is  a  tendency  to  form  a  'plow  sole'  or  '  hardpan.'" 

(520  Ib.  P.)  "Practically  all  of  this  type  is  under  cultivation,  and  is  highly 
prized  for  the  production  of  cotton.  The  yields  are  not  so  high  in  some  in- 
stances as  on  the  Houston  clay  and  other  prairie  types,  but  it  is  considered  a 
safer  soil  from  year  to  year  than  the  prairie  type.  Cotton  yields  from  one 
half  to  i  bale  per  acre.  As  much  as  ij  bales  per  acre  has  been  produced 
where  the  land  has  been  heavily  fertilized.  Very  little  corn  is  grown,  as  it  is 
claimed  that  the  yields  are  generally  light.  The  difficulty  here,  as  with  the 
Orangeburg  fine  sandy  loam,  is  that  the  soil  proper  is  shallow."  (Report  for 
1905,  page  436.) 

In  the  same  report  (page  438)  the  Orangeburg  fine  sandy  loam, 
mentioned  above,  is  described  as  follows: 

"  Cotton  is  the  principal  crop  grown  on  the  Orangeburg  fine  sandy  loam. 
The  yields  range  from  one  fourth  to  i  bale  per  acre,  depending  upon  the  amount 
of  fertilizers  used  and  the  methods  of  cultivation.  It  is  not  considered  a  good 
corn  soil,  and,  as  a  result,  not  much  corn  is  planted.  Corn  yields  range  from 

10  to  20  bushels  per  acre." 

Crowley  silt  loam  (Louisiana)  "usually  has  a  surface  of  about  16  inches.  It 
is  of  a  brown  color  when  wet,  but  ash  gray  when  dry.  It  is  composed  of  fine 
sand  and  silt,  with  sufficient  clay  to  render  it  rather  impervious.  If  stirred  when 
wet,  it  puddles  somewhat.  This  soil  is  underlain  by  a  clay  of  mottled  brown 
and  yellow  color,  with  brick -red  streaks  and  blotches.  The  subsoil  is  highly 
impervious  and  the  surface  level,  so  that  the  soil  has  very  poor  drainage.  The 
samples  analyzed  are  from  level  prairies  in  southern  Louisiana. " 

(1220  Ib.  P.)  "From  the  time  that  the  Crowley  silt  loam  was  first  cul- 
tivated, rice  has  been  the  only  crop  to  receive  attention.  Nothwithstanding 
this  continued  annual  cropping  with  the  same  crop,  without  attempting  in  any 
way  to  maintain  the  productiveness  of  the  soil,  there  has  as  yet  been  no  de- 
crease in  yields."  (Report  for  1903,  page  470.) 


I44  SCIENCE   AND   SOIL 

Orangeburg  fine  sandy  loam  (Texas).  "Varies  in  color,  being  red,  brown, 
or  gray.  It  is  a  light  sandy  loam,  generally  carrying  iron  concretions.  The 
subsoil  is  red,  friable,  sandy  clay.  The  type  occupies  the  upland  and  has  good 
natural  drainage." 

(960  Ib.  P.)  "  Cotton  is  the  principal  crop  raised  upon  this  soil.  Yields  from 
one  half  to  three  fourths  of  a  bale  per  acre  are  secured.  Corn  does  fairly  well. " 
(Report  for  1903,  page  495.) 

GLACIAL  OR  LOESSIAL  SOILS 

Shelby  silt  loam  (Missouri)  "  is  a  silty  soil  of  medium  depth  and  of  a  light 
gray  color  when  dry;  dark  gray  when  wet.  It  grades  into  a  stiff,  impervious 
silty  clay,  plastic  and  waxy  when  wet,  friable  and  loamy  when  dry.  The  sub- 
soil is  a  dark  mottled  clay.  It  is  level  or  gently  rolling.  The  original  growth 
on  this  type  of  soil  was  the  prairie  grasses. " 

(1920  Ib.  P.)  "The  following  yields  are  secured  on  this  soil  in  good  seasons : 
Hay,  from  2  to  3  tons;  corn,  from  35  to  40  bushels;  oats,  30  to  60  bushels; 
wheat,  15  to  20  bushels,  but  uncertain;  Kafir  corn,  20  to  40  bushels;  mil- 
let, 30  to  40  bushels  of  seed  per  acre.  The  Shelby  silt  loam  is  a  typical 
grass  soil."  (Report  for  1903,  page  884.) 

Marshall  loam  (Minnesota)  "is  a  somewhat  heavy  loam  from  10  to  12  inches 
in  depth  and  of  a  dark  brown  color.  Under  this  is  a  stiff,  sticky  yellow  subsoil 
to  a  depth  of  about  3  feet.  Below  this  is  a  stiff  bowlder  clay,  mottled  yellow 
and  gray.  The  type  is  generally  rolling  and  well  drained.  Bowlders  and 
glacial  gravel  occur  to  some  extent  over  this  soil." 

(1830  Ib.  P.)  "The  Marshall  loam  is  the  safest  soil  in  the  area,  as  it  is  the 
surest  to  produce  at  least  an  average  crop.  .  .  .  The  Marshall  loam,  taken 
as  a  whole,  excels  all  other  soil  types  of  the  area  in  the  production  of  wheat, 
on  account  of  the  superior  quality  of  the  grain  produced."  (Report  for  1903, 
page  820.) 

Marshall  silt  loam  (Wisconsin)  "is  a  mealy,  chocolate-colored  silt  loam 
with  a  dark  brown  tint  when  moist.  It  contains  a  large  amount  of  silt,  and 
becomes  somewhat  sticky  when  wet.  It  is  about  10  inches  deep.  The  sub- 
soil is  a  sticky,  reddish-yellowish  silty  clay,  about  3  feet  deep,  and  rests  upon  a 
glacial  gravel  or,  the  disintegrating  limestone  of  the  region.  The  soil  probably 
owes  some  of  its  distinguishing  characteristics  to  the  influence  of  this  limestone. 
The  type  is  rolling  and  well  drained.  It  was  originally  covered  with  the  prairie 
grasses  of  the  region. " 

(2450  Ib.  P.)  "It  is  one  of  the  strongest  and  most  fertile  soil  types  of  the 
region,  forming  the  larger  portion  of  the  original  rolling  prairie  of  southern 
Wisconsin.  It  produces,  under  average  seasonal  conditions,  from  50  to  60 
bushels  of  corn,  from  40  to  50  bushels  of  oats,  about  ij  tons  of  hay,  and  1200 
pounds  of  tobacco. "  (Report  for  1902,  page  557.) 

Miami  silt  loam  (Wisconsin)  "is  a  very  silty  loam,  light  brown  when  wet, 
and  light  gray  when  dry.  Its  depth  is  about  8  inches.  It  is  underlain  by  several 


ANALYSIS   BY  THE   UNITED    STATES   BUREAU     145 

feet  of  stiff,  yellow,  silty  clay  that  is  always  mottled  with  gray,  showing  poor 
drainage  and  aeration.  This  type  originally  consisted  mainly  of  timber  lands 
and  oak  openings. " 

(2100  Ib.  P.)  "The  crop  yields  on  the  Edgerton  (Miami)  silt  loam  average 
from  45  to  50  bushels  of  corn  per  acre,  about  40  bushels  of  oats,  from  i  to  i£ 
tons  of  hay,  and  from  noo  to  1200  pounds  of  tobacco."  (Report  for  1902, 

page  55  7-) 

Marshall  black  clay  loam  (Illinois)  "is  a  heavy,  somewhat  sticky,  granular 
clay  loam,  containing  a  large  percentage  of  silt  and  organic  matter.  It  has 
a  depth  of  about  18  inches.  The  subsoil  is  a  mottled  yellow  or  drab-colored 
sticky,  silty  clay.  This  soil  type  has  formed  where  the  natural  drainage  was 
poor.  The  surface  is  level.  In  its  original  condition  it  was  wet  and  swampy 
and  required  thorough  drainage. " 

(2970  Ib.  P.)  "There  are  few  soils  more  productive  than  the  Miami  (Mar- 
shall) black  clay  loam.  Some  areas  have  been  cropped  almost  continuously 
in  corn  for  nearly  fifty  years  without  much  diminution  in  the  yields,  but  the 
effect  will  undoubtedly  be  seen  if  the  practice  is  continued  much  longer." 
(Report  for  1903,  page  787.) 

Marion  silt  loam  (Illinois,  gray  silt  loam  on  tight  clay)  "consists  of  a  light 
brown  to  whitish  very  silty  loam,  containing  very  little  organic  matter.  Its  depth 
averages  12  inches.  The  soil  cakes  on  drying,  but  breaks  down  into  flourlike 
dust  when  pulverized.  The  subsoil  is  heavier,  and  contains  more  clay.  It  is  so 
impervious  to  water  as  to  be  locally  called  hardpan.  The  lower  subsoil  is  a 
hard,  silty,  mottled  yellow  clay,  often  containing  iron  concretions.  Below  4 
or  5  feet,  more  or  less  gravel  is  found.  The  type  is  level  or  slightly  rolling. 
The  soil  has  very  poor  natural  drainage,  owing  to  the  rather  impervious 
subsoil  and  the  level  surface.  While  of  loessial  origin,  this  soil  has  been 
largely  formed  from  sandstones  and  shales  ground  up  by  glaciers." 

(1050  Ib.  P-)  "The  average  yield  of  corn  is  not  much  more  than  15  bushels 
per  acre.  .  .  .  The  Marion  silt  loam  is  not  a  strong  soil,  and  is  not  well  adapted 
to  general  farming  purposes.  The  small  yield  of  corn  indicates  that  it  is  not 
a  good  soil  for  that  crop,  although  the  profit  from  corn,  according  to  many 
farmers,  is  as  much  as  from  other  crops. "  (Report  for  1902,  page  542.) 

Miami  sand  (Ohio)  "is  a  coarse  to  medium  loose  and  deep  yellowish  sand. 
It  is  underlain  by  a  yellow  sand  of  about  the  same  texture.  It  is  level  to  rolling, 
and  consists  of  glacial  material  somewhat  modified  by  wind  action.  It  occupies 
elevated  positions,  and  is  well  drained. " 

(2360  Ib.  P.)  "Grass,  corn,  wheat,  truck,  and  fruit  are  grown  on  this  soil. 
The  quality  of  these  is  good,  and  in  some  cases  better  than  the  produce  grown  on 
the  other  soils  in  the  area,  but  the  yield  is  usually  15  to  30  per  cent  less,  and  crops 
sometimes  are  cut  short  or  fail  because  of  susceptibility  to  drought.  The 
yield  of  wheat  ranges  from  10  to  20  bushels  per  acre,  and  of  corn  from  20  to 
45  bushels  per  acre.  .  .  .  This  soil  yields  from  75  to  120  bushels  per  acre  of 
an  excellent  quality  of  potatoes. "  (Report  for  1902,  page  394.) 

W abash  loam  (Ohio)  "is  a  dark  brown  to  black  soil  of  good  depth,  and  con- 


146  SCIENCE  AND   SOIL 

taining  a  small  proportion  of  the  coarser  grades  of  sand.  The  subsoil  is  a 
heavy  brownish  yellow  loam  overlying  a  fine  gravelly  loam.  It  is  a  bottom 
land,  frequently  occurring  as  terraces.  It  is  generally  well  drained.  It  con- 
sists of  glacial  drift  redeposited  by  stream  action." 

(1570  Ib.  P.)  "One  of  the  more  fertile  soils  of  the  area.  Some  of  the  fields, 
tilled  for  more  than  half  a  century  and  only  moderately  manured,  still  produce 
abundantly.  .  .  .  Corn  yields  from  40  to  100  bushels  per  acre,  with  the  aver- 
age production  probably  about  75  bushels,  and  wheat  from  20  to  35  bushels 
per  acre."  (Report  for  1902,  page  395.) 

Volusia  silt  loam  (Ohio)  "is  a  gray  to  brown  silty  loam  with  an  average 
depth  of  8  inches.  The  subsoil  is  a  light  yellow  silty  loam,  mottled  with  gray 
in  its  lower  portions.  It  has  resulted  in  most  part  from  the  glaciation  of  shales. 
Its  mechanical  constituents  closely  resemble  in  size  those  of  the  soils  derived 
from  the  loess,  being  composed  largely  of  silt.  This  is  doubtless  due  to  the  silt 
in  the  shales  from  which  this  soil  type  comes  in  large  part. " 

(1480  Ib.  P.)  "The  average  yield  of  wheat  is  about  20  bushels  per  acre, 
and  yields  as  high  as  30  bushels  are  not  uncommon.  Corn,  under  the  best 
cultural  methods,  will  average  40  to  45  bushels  per  acre.  Oats  will  yield  an 
average  of  50  bushels  per  acre,  although  larger  yields  are  often  reported. 
From  100  to  150  bushels  of  marketable  potatoes  per  acre  is  the  average  produc- 
tion of  this  crop."  (Report  for  1904,  page  559.) 

Podunk  fine  sandy  loam  (Connecticut)  "is  an  alluvial  soil,  formed  by  the 
reworking  by  running  water  of  glaciated  granites,  gneisses,  and  schists.  It 
contains  an  abundance  of  micaceous  mineral  particles  visible  to  the  eye.  It  is 
underlain  by  fine  sand.  The  soil  is  of  a  dark  brown  color  and  is  well  drained. 
The  tobacco  field  from  which  the  sample  came  had  been  heavily  fertilized  for 
years. " 

(1920  Ib.  P.)  "The  type  is  entirely  under  cultivation  and  produces  good 
crops  of  corn,  late  truck,  cucumbers  for  pickling,  and  tobacco.  The  area  in 
the  latter  crop  is  large,  and  the  yields  range  from  1700  to  1900  pounds  in  the 
open  field."  (Report  for  1903,  page  54.) 

RESIDUAL  SOILS 

Oswego  silt  loam  (Kansas)  "consists  of  a  dark  gray  silty  loam,  varying 
from  very  shallow  to  10  inches  deep,  which  grades  into  a  stiff  clay,  becoming  more 
impervious  with  depth.  It  becomes  hard  and  compact  on  drying,  but  it  is  easily 
broken  up  into  a  mellow  loam  if  plowed  when  in  proper  condition  of  moisture. 
This  is  an  upland  type,  and  occupies  gently  rolling  prairies.  Owing  to  the 
topography  of  the  country,  the  type  has  good  surface  drainage.  The  Oswego 
silt  loam  is  derived  from  the  weathering  of  the  underlying  rock,  this  usually 
being  shales,  with  occasional  interbedded  layers  of  sandstone  and  limestone. 

(1050  Ib.  P.)  "The  Oswego  silt  loam  is  not  a  strong  soil It  is 

better  adapted  to  wheat  than  to  any  of  the  other  crops  grown  in  the  area,  but, 
even  with  wheat,  commercial  fertilizer  costing  about  $1.25  an  acre  is  used  on 


ANALYSIS    BY   THE   UNITED   STATES    BUREAU     147 

this  soil,  while  none  is  deemed  necessary  on  the  other  soils."  (Report  for 
1903.  Page  897.) 

W abash  silt  loam  (Kansas)  "varies  from  12  to  24  inches  in  depth  and  con- 
sists of  a  dark  brown  to  black  heavy  silt  loam.  It  is  easily  cultivated  and 
readily  kept  in  good  tilth.  The  subsoil  consists  of  a  compact  and  rather  heavy 
brown  or  yellowish  silt  loam.  It  occurs  as  long,  narrow,  tracts  in  the  creek 
valleys  and  along  the  outer  edges  of  the  river  valleys.  The  type  occupies  a 
rather  low  position  in. stream  valleys  and  on  gentle  slopes.  Its  surface  is 
nearly  level  or  gently  sloping.  It  forms  first  bottoms  of  smaller  streams  and 
second  bottoms  of  larger  ones.  It  is  well  drained  naturally.  The  type  has  been 
deposited  by  water,  the  surface  consisting  largely  of  material  washed  from  the 
surrounding  hills,  which  are  made  up  of  shales  and  limestones.  This  wash 
from  the  hills  is  continually  adding  to  the  type. " 

(1140  Ib.  P.)  "Corn  is  the  most  important  crop,  and  yields  from  30  to 
75  bushels  per  acre,  40  to  45  bushels  being  an  average  yield  in  ordinary 
seasons.  Alfalfa,  a  very  important  crop  on  this  type,  yields  3  to  5  cuttings 
a  year,  and  averages  about  i  ton  per  acre  for  each  cutting.  The  average  an- 
nual yield  is  probably  3  or  4  tons  of  cured  hay  per  acre.  Wheat  yields  from 
20  to  35  bushels  per  acre.  .  .  .  The  land  is  cropped  constantly,  but  as  yet 
the  yields  have  not  diminished  greatly,  although  no  fertilizer  and  very  little 
manure  is  used.  The  soil  is  naturally  rich  in  organic  matter,  which  may 
account  for  its  continued  productiveness.  Corn  is  often  cropped  year  after 
year  on  this  type,  and  no  system  of  rotation  is  used."  (Report  for  1906,  page 

932.) 

Hagerstown  day  (Kentucky)  "has  a  heavy  texture,  and  varies  from  3  to  12 
inches  in  depth.  It  is  yellow  or  brown  in  color.  The  subsoil  is  a  heavy  yellow 
clay,  extending  to  a  depth  of  3  or  more  feet.  This  soil  type  is  derived  from 
limestones  and  shales.  These  rocks  offer  considerable  resistance  to  disinte- 
gration, and  the  soil  may  therefore  be  more  thoroughly  leached  than  would  be 
the  case  were  the  rocks  more  readily  decomposed.  The  surface  is  rather 
rough,  rounded  hills  being  dominant  features.  Surface  washing  has  been  great, 
and  the  soil  is  generally  shallow,  the  depth  depending  on  its  position.  This 
is  a  residual  soil,  being  formed  from  the  breaking  down  in  place  of  the  underlying 
limestones  and  shales." 

(3490  Ib.  P.)  "Tobacco  yields  from  800  to  1200  pounds;  wheat  from  25  to 
35  bushels;  corn  from  25  to  40  bushels;  and  hay  from  i?  to  2  tons  to  the  acre. 
.  .  .  On  the  stony  phase  of  this  soil  the  same  crops  are  produced,  but  the 
yields  are  lower  —  tobacco,  500  pounds ;  corn,  about  25  bushels ;  wheat,  less 
than  12  bushels.  .  .  .  The  Hagerstown  clay  is  a  good  grain  and  grass  land, 
but  it  is  rapidly  deteriorating  from  continuous  surface  washing.  .  .  .  Unless 
better  methods  are  speedily  adopted,  this  soil  type  will  soon  reach  the  condition 
of  its  stony  phase,  locally  known  as  the  '  barren  limestone'  land. "  (Report  for 
1903,  page  626.) 

Hagerstown  loam  (Tennessee)  "  consists  of  brown  or  yellowish  brown  mellow 
loam  from  9  to  12  inches  deep.  It  is  underlain  by  a  yellow  to  reddish  yellow 


148  SCIENCE  AND   SOIL 

stiff  loam  or  light  clay  loam, -which  becomes  a  more  pronounced  red  in  depth. 
Traces  of  chert  are  found  in  both  soil  and  subsoil.  This  type  was  formed  by 
the  slow  weathering  of  limestones.  In  this  soil  the  weathering  has  been  so 
complete  and  the  leaching  so  excessive  that  the  lime  of  the  disintegrated  stone 
has  been  largely  washed  from  the  soil.  The  type  has  a  moderately  rolling  sur- 
face, and  has  good  surface  drainage,  but  the  subsoil  is  rather  impervious.  The 
underlying  limestone  comes  near  the  surface  in  some  places,  owing  to  erosion. " 

(1050  Ib.  P.)  "The  Hagerstown  loam  is  all  used  in  the  extensive  system 
of  general  farming  which  is  practiced  throughout  the  area.  Corn  yields  from 
15  to  30  bushels,  with  a  probable  average  of  22  bushels  per  acre.  Wheat 
yields  from  5  to  20  bushels,  with  an  average  of  10  bushels,  and  the  compara- 
tively small  amount  of  hay  which  is  grown  yields  an  average  crop  of  i  ton  per 
acre."  (Report  for  1903,  page  584.) 

Houston  clay  (Alabama)  "has  resulted  from  the  weathering  of  rotten 
limestones  or  chalks  of  Cretaceous  time.  Owing  to  its  proximity  to  the  soft 
and  easily  broken  down  lime  rock,  this  soil  is  highly  calcareous,  and  often 
contains  lime  concretions,  especially  in  the  subsoil.  It  may  be  considered  to 
be  of  comparatively  recent  origin  .and  as  a  residual  Coastal  Plains  soil.  The 
soil  is  a  gray,  brown,  or  black  loamy  clay,  6  inches  deep.  This  is  underlain 
with  3  feet  or  more  of  heavy  gray  or  mottled  yellow  clay.  The  surface  is  gently 
rolling  and  the  drainage  very  good.  Agriculturally,  the  soil  is  lighter  than 
would  be  expected,  from  its  high  clay  content.  This  may  be  due  to  floccula- 
tion  by  the  high  percentage  of  lime  present. " 

(5150  Ib.  P.)  "The  Houston  clay,  while  clodding  badly  when  plowed  too 
wet,  and  requiring  care  in  its  management,  is  a  very  strong  and  productive 
soil."  (Report  for  1905,  page  464.) 

Cecil  clay  (North  Carolina)  "is  found  on  uplands,  gentle  slopes,  and  roll- 
ing lands  of  the  Piedmont  Plateau.  The  Cecil  clay  is  a  residual  soil,  result- 
ing from  the  disintegration  of  a  number  of  rocks,  differing  in  mineralogical 
characters.  Granites,  gneisses,  schists,  and  other  somewhat  similar  rocks  have 
contributed  to  the  formation  of  this  type,  and  so  thorough  have  been  the  dis- 
integration and  decomposition  that  the  same  red  clay  results  from  all.  There 
is  such  a  gradual  change  from  soil  to  the  parent  rock  that  there  is  generally  no 
sharp  line  between  the  two.  The  soil  consists  of  a  heavy  red  loam,  contain- 
ing many  sand  grains  of  the  original  minerals  forming  the  rocks  from  which  the 
soil  is  derived.  It  is  shallow,  averaging  about  5  inches.  The  subsoil  is  a 
stiff,  tenacious  red  clay  to  a  depth  of  3  or  more  feet.  It  becomes  heavier 
at  greater  depths.  Natural  drainage  is  fairly  good,  probably  due  to  the  sand 
and  rock  fragments  contained  in  soil  and  subsoil." 

(960  Ib.  P.)  "The  soil  is  generally  thin,  but  can  be  deepened  by  proper 
methods  of  cultivation  and  by  green  manuring.  When  so  deepened,  it  assumes 
the  properties  of  a  heavy  clay  loam,  and  is  very  productive.  It  requires, 
however,  considerable  care  and  labor  to  maintain  its  fertility."  (Report  for 
1901,  page  55.) 


ANALYSIS   BY  THE   UNITED    STATES   BUREAU     149 

The  average  yields  of  corn,  wheat,  and  oats  are  reported  as  18, 
12,  and  20  bushels,  respectively,  per  acre.  In  the  description  of 
this  same  type  of  soil  for  the  Leesburg  area  of  Virginia,  the  follow- 
ing statements  were  recorded  by  the  field  men  of  the  Bureau  of 
Soils : 

"The  soil  responds  readily  to  applications  of  lime,  and  is  much  benefited 
by  its  use.  Much  commercial  fertilizer,  as  well  as  lime  and  barn-yard  manure, 
is  used  on  this  soil.  In  fact,  so  much  acid  phosphate  has  been  added  of  late 
years  that  the  land  has  become  quite  sour,  and  it  is  hardly  possible  to  obtain  a 
stand  of  grass  or  clover  without  the  use  of  lime. "  (Report  for  1903,  page  221.) 

Porter's  black  loam  (Virginia)  "is  a  loose,  mellow  black  loam,  averaging 
about  12  inches  deep.  The  subsoil  is  slightly  heavier  and  of  a  light  brown  to 
yellowish  color.  In  depressions  and  coves,  where  wash  from  the  higher  ground 
has  accumulated,  there  is  no  sharp  distinction  between  soil  and  subsoil,  the 
loose  black  loam  being  several  feet  deep.  Both  soil  and  subsoil  contain  frag- 
ments of  the  rocks  whose  decomposition  has  formed  the  soil  —  granites, 
gneisses,  and  schists.  This  type  occurs  principally  in  the  coves  of  the  Blue 
Ridge  Mountains,  but  is  also  found  upon  the  tops  and  upper  slopes. " 

(4630  Ib.  P.)  "Locally  the  Porter's  black  loam  is  called  'black  land' 
and  '  pippin  land,'  the  latter  term  being  applied  because,  of  all  the  soils  in  the 
area,  it  is  preeminently  adapted  to  the  production  of  the  Newtown  or  Albe- 
marle  Pippin.  This  black  land  has  long  been  recognized  as  the  most  fertile 
of  the  mountain  soils.  It  can  be  worked  year  after  year  without  apparent  im- 
pairment of  its  fertility."  (Report  for  1902,  page  210.) 

Chester  mica  loam  (Maryland)  "as  its  name  indicates,  is  characterized 
oy  a  great  quantity  of  micaceous  particles.  It  is  derived  from  granites,  gneisses, 
and  other  micaceous  rocks  over  which  the  type  lies.  It  is  strictly  a  resid- 
ual soil  and  consists  of  a  brownish  loam  10  to  15  inches  deep,  underlain  by  a 
lighter  colored,  heavier  loam,  also  containing  mica.  The  surface  varies  from 
gently  rolling  to  somewhat  hilly. " 

(1130  Ib.  P.)  "It  is  not  naturally  a  strong  soil,  but  is  susceptible  of  being 
made  quite  fertile  and  productive  through  intelligent  tilling  and  manuring." 
(Report  for  1901,  page  222.) 

Collington  sandy  loam  (New  Jersey)  "has  resulted  from  the  weathering 
of  the  greensand,  or  glauconite,  of  New  Jersey.  The  subsoil,  which  comes 
within  6  or  8  inches  of  the  surface,  is  a  sticky,  tenacious,  claylike  material,  yel- 
lowish or  greenish  in  color.  Owing  to  its  relations  to  the  greensand  deposits, 
this  type  differs  from  the  other  Coastal  Plains  soils. " 

(From  260  Ib.  P.  in  surface  to  27,600  Ib.  P.  in  lower  subsoil.)  "  Since  millions 
of  tons  of  this  greensand  marl  have  been  employed  as  fertilizers,  it  is  at  once 
evident  that  any  soil  possessing  a  subsoil  of  this  material  will  contain  more  than 
the  ordinary  amounts  of  potash  and  lime.  When,  in  addition  to  this,  its  phys- 
ical structure  is  also  well  adapted  to  crop  production,  it  would  seem  that  a 
particularly  valuable  soil  was  formed.  .  .  .  The  marl  specimen  was  collected 


SCIENCE   AND   SOIL 

as  a  sample  to  show  the  amounts  of  plant  foods  in  the  material  actually  used  as 
a  fertilizer.  The  potash  content  is  not  high  for  a  greensand  marl,  but  the 
phosphoric-acid  content  is  unusually  high.  The  subsoil  analysis  (by  acid 
digestion)  reveals  the  fact  that  the  lime,  potash,  and  phosphoric  acid  of  the 
original  material  have  been  extensively  dissolved  and  removed,  though  fair 
amounts  still  remain. "  (Report  for  1901,  page  139.) 

Unless  otherwise  stated,  the  above  quotations  from  the  soil 
survey  field  men  and  from  Bureau  of  Soils  Bulletin  54  refer  specifi- 
cally to  the  areas  in  which  the  samples  analyzed  (Table  22)  were 
collected. 

In  general,  there  is  very  distinct  correlation  between  the  compo- 
sition of  these  extensive  soil  types  and  their  natural  productive- 
ness as  recorded  by  the  soil  surveyors  themselves  some  years  be- 
fore the  chemical  analyses  were  made.  It  should  be  kept  in  mind 
that  the  data  reported  in  Table  22  are  for  amounts  in  2  million 
pounds  of  ignited  soil,  and  are  thus  somewhat  higher  than,  and  not 
strictly  comparable  with,  the  results  of  analyses  of  the  ordinary 
dry  soil.  It  is  important,  also,  to  know  that  most  of  the  27  type 
soils  described  are  found  not  only  in  the  state  and  area  in  which 
these  analyzed  samples  were  taken,  but  are  widely  distributed 
throughout  the  respective  formations,  as  the  Coastal  Plains,  glacial 
areas,  Piedmont,  or  other  regions.  Thus  the  1903  Report  of  Field 
Operations  of  the  Bureau  of  Soils  mentions  that  Norfolk  sand  was 
found  that  year  in  New  York,  Delaware,  Maryland,  Virginia,  North 
Carolina,  Georgia,  Florida,  and  Alabama;  and  Marshall  black  clay 
loam  has  been  reported  for  Ohio,  Indiana,  Michigan,  Wisconsin, 
Illinois,  Iowa,  Minnesota,  South  Dakota,  and  North  Dakota. 

The  Bureau  of  Soils  includes  in  the  one  soil  type  (Marshall  silt 
loam)  the  common  brown  silt  loams  of  the  Middle  and  Upper 
Illinoisan  glaciations,  of  the  Pre-Iowan,  lowan,  and  Early  Wiscon- 
sin glaciations,  in  Illinois,  as  well  as  soil  in  the  Janesville  and 
Viroqua  areas  of  Wisconsin,  in  the  Grand  Island  and  Staunton 
areas  of  Nebraska,  and  in  the  Jamestown  area  of  North  Dakota, 
with  other  areas  in  Colorado,  Minnesota,  Kansas,  Missouri,  Iowa, 
Indiana,  and  Louisiana;  but  it  is  apparent  that  the  ultimate 
chemical  composition  of  the  soil  is  not  considered  among  the 
characteristics  required  by  the  Bureau  for  a  soil  type.  Thus  the 
Marshall  silt  loam  (brown  silt  loam)  of  the  Middle  Illinoisan  glacia- 


ANALYSIS   BY   THE   UNITED   STATES   BUREAU     151 

tion  contains  1 1 70  pounds  of  total  phosphorus  in  2  million  of  dry 
soil  (see  Table  15),  while  2450  pounds  are  reported  in  2  million 
pounds  of  ignited  soil  of  the  Wisconsin  area  (see  Table  22).  Doctor 
Fraps  finds  480  pounds  of  acid-soluble  phosphorus  in  2  million 
pounds  of  the  Houston  day  of  Texas  from  samples  furnished  him 
by  the  Bureau  of  Soils,  while  Table  22  shows  5150  pounds  of  total 
phosphorus  in  2  million  pounds  of  ignited  Houston  clay  of  Alabama. 
The  Texas  soil  is  evidently  very  deficient  in  phosphorus,  but  this 
is  certainly  not  the  case  with  the  Alabama  soil,  which,  it  will  be 
seen,  outranks  in  phosphorus  content  every  other  soil  reported  in 
Table  22.  The  Bureau  of  Soils  has  not  reported  the  ultimate  chemi- 
cal analyses  of  different  samples  of  the  same  type  soil  from  different 
areas,  so  that  it  is  impossible  to  make  any  such  comparative  study 
from  the  Bureau's  data  alone. 

In  the  author's  opinion,  the  exact  chemical  data  from  which 
Table  22  is  derived,  and  the  careful  descriptions  given  of  the  type 
soils  analyzed,  constitute  the  most  valuable  contribution  of  the 
United  States  Bureau  of  Soils  to  American  agriculture.  This 
absolute  invoice  of  plant  food,  together  with  the  description  of 
physical  properties,  crop  adaptations,  and  topographic  features, 
furnishes  a  basis  for  the  intelligent  consideration  of  possible 
permanent  and  profitable  systems  of  agriculture.  Actual  field 
experiments,  to  determine  the  rate  at  which  the  plant  food  can  be 
made  available,  are  lacking,  and  no  report  is  made  of  the  nitrogen 
content  of  the  soils  or  of  the  limestone  present  or  required.  The 
percentages  of  "  lime  "  (CaO)  and  magnesia  (MgO)  are  given  in 
Bulletin  54,  but  these  signify  little  or  nothing  in  relation  to  lime. 
Even  the  very  acid  Marion  silt  loam  of  Clay  County,  Illinois  (gray 
silt  loam  on  tight  clay),  is  reported  by  the  Bureau  to  contain  .56 
per  cent  of  CaO  (5.6  tons  in  2  million  pounds  of  soil),  whereas  it 
contains  neither  calcium  oxid  nor  calcium  carbonate,  the  calcium 
present  existing  usually  in  acid  silicates. 

In  general,  the  work  of  the  Bureau  of  Soils  has  been  directed 
toward  a  study  of  crop  adaptation,  in  accordance  with  a  somewhat 
prevalent  notion  that  every  soil  is  intended  to  grow  some  definite 
crop  or  crops,  and  that  success  will  be  attained  if  the  proper  crop 
is  found  for  the  special  soil.  While  all  must  recognize  that  the 
natural  adaptation  of  soil  and  crop  is  an  important  factor  in  many 


1 52  SCIENCE   AND    SOIL 

cases,  in  the  author's  opinion  it  is  a  matter  which  has  been  given 
undue  consideration  in  comparison  with  other  extremely  important 
factors. 

Even  in  the  common  practice  of  agriculture,  soils  at  first  well 
adapted  to  the  growing  of  a  certain  crop  do  not  remain  so  adapted. 
The  fact  is  too  well  known  to  need  illustration  that  specific  crops 
are  often  grown  with  success  for  years  finally  to  fail  and  be  aban- 
doned for  some  other  successful  crops,  which  in  turn  finally  give 
way  to  others.  Thus  good  wheat  land  finally  becomes  poor  wheat 
land,  but  still  remains  good  for  timothy  hay,  which  in  turn  gives 
way  to  red  top,  and  this  may  be  followed  by  partial  abandonment 
of  the  land  for  crop  production. 

At  any  stage  in  this  process  of  soil  depletion,  the  land  may  be 
restored  to  its  original  power  to  produce  wheat,  by  adopting  the 
proper  systems  of  soil  enrichment. 

When  land  refuses  longer  to  grow  any  crop  wyhich  it  has  formerly 
produced  writh  satisfaction  and  profit,  the  landowner  should,  as 
a  very  general  rule,  find  out  wrhat  the  trouble  is,  and  then  proceed 
to  remedy  it;  but,  instead  of  meeting  and  overcoming  such  diffi- 
culties, the  American  farmer  has  literally  run  away  from  them; 
either  by  seeking  newer  lands  or  by  adopting  any  other  crop  which 
the  land  would  still  produce. 

The  most  common  staple  crops  can  be  grown  on  almost  any  soil 
if  it  is  well  drained,  well  watered,  and  sufficiently  rich.  Of  course, 
the  matter  of  crop  adaptation  must  not  be  ignored,  but  if  we  would 
grow  either  plants  or  animals,  we  must  not  neglect  the  food  supply. 


CHAPTER  X 

CROP  REQUIREMENTS  FOR  NITROGEN,  PHOSPHORUS,  AND 
POTASSIUM 

A  STUDY  of  Table  23  is  sufficient  to  make  one  familiar  with  the 
requirements  of  the  more  important  crops  of  the  United  States  for 
the  three  plant-food  elements  that  are  now  recognized  as  having 
money  values  in  commercial  fertilizers.  Information  is  also  given 
regarding  the  amounts  of  these  three  elements  in  different  parts  of 
the  crop,  as  in  grain,  straw,  corn  stover,  and  cotton  stalks  and  lint, 
in  order  that  it  may  be  known  with  some  degree  of  accuracy  how 
much  of  each  element  is  removed  from  the  soil  in  crops  and  how 
much  is  sold  from  the  farm  in  different  kinds  of  farm  produce. 
The  ideal  practice  is  to  return  to  the  soil,  either  directly  or  in 
farm  manure,  all  plant  food  not  sold  from  the  farm. 

The  data  given  in  Table  23  are  on  the  basis  of  pounds  per  acre 
for  crop  yields  which  are  large,  but  which,  when  the  best  condi- 
tions are  provided,  have  been  and  may  be  produced  with  very  great 
profit,  —  yields  that  may  well  stand  as  ideals,  desirable  and  pos- 
sible to  be  attained.  Approximately  proportionate  amounts  of 
plant  food  would  be  required  for  any  other  yields.  Thus,  if  it  is 
preferred  to  plan  to  make  possible  yields  only  one  half  as  large, 
then  the  amounts  given  in  Table  23  may  be  divided  by  two.  (In 
Section  3  of  the  Appendix,  data  are  reported  showing  the  more  com- 
plete composition  of  a  much  larger  number  of  crops,  but  the  re- 
sults there  given  are  derived  from  a  smaller  number  of  analyses 
than  are  represented  for  the  crops  reported  in  Table  23;  and, 
consequently,  some  differences  are  to  be  expected.) 

The  value  of  the  elements  is  computed  on  the  basis  of  the  present 
market  prices  for  plant  food  from  the  most  abundant  natural 
deposits,  delivered  in  car-load  lots  to  central  Illinois,  and  in  suit- 
able condition  for  direct  application  to  the  land. 

Nitrogen  in  sodium  nitrate 15  cents  a  pound. 

Phosphorus  in  ground  raw  phosphate     ...       3  cents  a  pound. 
Potassium  in  kainit 6  cents  a  pound. 


154 


SCIENCE   AND    SOIL 


TABLE  23.   FERTILITY  IN  FARM  PRODUCE 
Approximate  maximum  amounts  removable  per  acre  annually 


PRODUCE 

] 

3OUNDS 

MARKET 

VALUE 

Nitro- 

Phos- 

Potas- 

Nitro- 

Phos- 

Potas- 

Total 

Kind 

Amount 

gen 

phorus 

sium 

gen 

phorus 

sium 

Value 

Corn,  grain 

100  bu. 

IOO 

17 

19 

$15.00 

$   -51 

fc   I.I4 

$16.65 

Corn  stover 

3T. 

48 

6 

52 

7-20 

.18 

3.12 

10.50 

Corn  crop  l 

148 

23 

71 

22.20 

.69 

4.26 

27-I5 

Oats,  grain 

100  bu. 

66 

II 

16 

9.90 

•33 

.96 

11.19 

Oat  straw   .     . 

4T. 

31 

5 

52 

4.65 

•15 

3.12 

7.92 

Oat  crop 

07 

16 

68 

14.55 

.48 

4.08 

IQ.II 

Wheat,  grain    . 

50  bu. 

7  1 

71 

12 

13 

10.65 

•36 

*f.V 

.78 

y 

11.79 

Wheat  straw    . 

2*T. 

25 

4 

45 

3-75 

.12 

2.70 

6-57 

Wheat  crop 

96 

16 

58 

14.40 

.48 

3-48 

18.36 

Soy  beans    .     . 

25  bu. 

80 

13 

24 

I2.OO 

•39 

1.44 

13-83 

Soy  bean  straw 

2JT. 

79 

8 

49 

11.85 

.24 

2-94 

15-03 

Soy  bean  crop  . 

i59 

21 

73 

23-85 

•63 

4-38 

28.86 

Timothy  hay  . 

3T. 

72 

9 

7i 

IO.80 

•27 

4.26 

15-33 

Clover  seed 

4  bu. 

7 

2 

3 

1.05 

.06 

.18 

1.29 

Clover  hay 

4T. 

1  60 

2O 

120 

24.OO 

.60 

7.20 

31.80 

Cowpea  hay     . 

3T. 

130 

14 

98 

19.50 

.42 

5.88 

25.80 

Alfalfa  hay 

8T. 

400 

30 

192 

6O.OO 

i.  08 

11.52 

72.60 

Cotton  lint  .     . 

1000  Ib. 

3 

0.4 

4 

•45 

.01  ' 

.24 

•  70 

Cotton  seed 

2000  Ib. 

63 

II 

19 

9-45 

•33 

1.14 

10.92 

Cotton  stalks   . 

4000  Ib. 

IO2 

18 

59 

15-3° 

•54 

3-54 

19.38 

Cotton  crop     . 

1  68 

29.4 

82 

25.20 

.88 

4.92 

31.00 

Potatoes      .     . 

300  bu. 

63 

13 

90 

9-45 

•39 

5-4° 

15-23 

Sugar  beets 

20  T. 

IOO 

18 

i57 

15.00 

•54 

9.42 

24.96 

Apples    .     .     . 

600  bu. 

47 

5 

57 

7-05 

•15 

3-42 

10.62 

Leaves    .     .     . 

4T. 

59 

7 

47 

8.85 

.21 

2.82 

11.88 

Wood  growth  . 

Atree 

6 

2 

5 

.90 

.06 

•3° 

1.26 

Total  crop  . 

112 

IA 

109 

1  6.  80 

42 

6  Zd 

21:       76 

Fat  cattle    .     . 

1000  Ib. 

25 

T- 

7 

i 

3-75 

•T- 

.21 

w*ot 

.06 

*O'  /** 

4.02 

Fat  hogs      .     . 

1000  Ib. 

18 

3 

i 

2.70 

.09 

.06 

2.85 

Milk  .... 

i  oooo  Ib. 

57 

7 

12 

8-55 

.21 

•72 

9.48 

Butter    .     .     . 

400  Ib. 

0.8 

0.2 

O.I 

.12 

.OI 

.01 

.14 

1  To  this  might  also  be  added  1000  pounds  of  corncobs,  containing  2  pounds  of 
nitrogen,  less  than  J  pound  of  phosphorus,  and  a  pounds  of  potassium. 


CROP   REQUIREMENTS  155 

The  figures  given  in  Table  23  are  based  upon  averages  of  large 
numbers  of  analyses  of  normal  products,  of  which  some  have  been 
made  by  the  author  and  his  associates,  and  many  others  by  various 
chemists  in  America  and  Europe.  These  averages  are  trustworthy 
for  large  crops  of  good  quality.  Abnormal  or  special  crops  may 
vary  considerably  from  these  averages.  Thus,  we  have  high-protein 
corn  and  low-protein  corn,  one  strain  requiring  50  per  cent  more 
nitrogen,  and  somewhat  more  phosphorus,  than  the  other  (Illinois 
Bulletins  87  and  128);  and  it  has  been  shown,  for  example,  that 
alfalfa  and  cowpeas  are  not  only  much  more  productive,  but  also 
much  richer  in  nitrogen,  when  grown  on  normal  soils  with  the 
proper  root-tubercle  bacteria  than  without  bacteria.  On  the 
whole,  however,  it  is  as  nearly  correct  to  say  that  a  fifty-bushel 
crop  of  wheat  requires  96  pounds  of  nitrogen  and  16  pounds  of 
phosphorus  as  it  is  to  say  that  a  measured  bushel  of  wheat  weighs 
60  pounds. 

It  may  be  said  that  other  similar  crops  resemble  somewhat 
closely  those  given  in  Table  23  as  to  plant-food  requirements. 
Thus  rye  and  barley  are  not  markedly  different  in  requirements 
from  wheat  and  oats,  considering  equal  yields  in  pounds  of  grain 
and  straw.  Other  root  crops  may  be  compared  with  sugar  beets, 
other  grasses  with  timothy,  hay  from  other  annual  legumes  with 
cowpea  hay,  and  other  biennial  and  perennial  legumes  may  be 
compared  in  a  general  way  with  red  clover  and  alfalfa. 

How  many  years  would  be  required  to  sell  as  much  phosphorus 
from  the  farm  in  cotton  lint  yielding  2  bales  (of  500  pounds  each) 
per  acre  as  in  4  tons  of  clover  hay,  which  may  be  produced  in  the 
two  cuttings  in  one  season?  Compare  the  nitrogen  and  potassium 
contained  in  100  bushels  of  corn  and  in  20  tons  of  sugar  beets. 
Compare  wheat  and  clover  in  plant-food  requirements. 

Assuming  that  two  thirds  of  the  nitrogen  used  by  the  clover 
plant  is  deposited  in  the  tops  and  only  one  third  in  the  roots,  and 
that  a  given  soil  will  furnish  as  much  nitrogen  to  a  growing  clover 
crop  as  to  a  growing  wheat  crop,  what  is  the  effect  upon  the  total 
nitrogen  content  of  the  soil  of  growing  clover  if  all  of  the  tops  are 
removed  ?  Compute  the  cost  of  commercial  nitrogen  for  a  5o-bushel 
crop  of  corn,  assuming  that  40  per  cent  of  the  nitrogen  applied  will 
be  lost  in  drainage  waters. 


CHAPTER  XI 

SOURCES    OF   PLANT   FOOD 

IF  the  productive  capacity  of  American  soils  is  to  be  maintained, 
elements  of  plant  food  which  are  present  in  such  small  amounts  as 
to  limit  the  crop  yields  even  under  good  systems  of  farming  must 
be  returned  to  the  soil  as  needed,  and  information  is  given  in  Table 
24  to  show  the  average  quantities  in  pounds  of  the  different  valu- 
able elements  of  plant  food  contained  in  one  ton  of  average  fresh 
farm  manure,  rough  feeds  and  bedding,  and  other  fertilizer  ma- 
terials. 

In  computing  the  value  of  plant  food  in  these  materials,  nitrogen 
is  counted  at  15  cents  a  pound  and  potassium  at  6  cents  a  pound; 
while  phosphorus  is  counted  at  3  cents  a  pound  in  raw  rock  phos- 
phate, at  10  cents  a  pound  in  bone  meal,  and  at  12  cents  a  pound  in 
acid  phosphate,  these  prices  being  based  upon  the  usual  average 
market  values  for  the  standard  fertilizing  materials  in  such  quanti- 
ties as  ought  to  be  purchased  by  farmers,  either  singly  or  by  two 
or  more  uniting. 

From  the  data  given  in  Tables  23  and  24  it  is  a  simple  matter  to 
compute  the  amounts  of  average  manure  or  other  fertilizers  neces- 
sary to  be  applied  to  the  land  to  replace  the  plant  food  removed  in 
any  rotation  of  crops.  Observe,  for  example,  that  a  four-year 
rotation,  including  corn  for  two  years,  oats  with  clover  seeding 
the  third  year,  and  clover  for  hay  and  seed  crops  the  fourth  year, 
would  require  39  tons  of  manure  to  supply  the  nitrogen,  41  tons 
to  supply  the  phosphorus,  40  tons  to  supply  the  potassium,  assum- 
ing the  yields  given  in  Table  23,  and  counting  that  the  clover  se- 
cures from  the  air  as  much  nitrogen  as  is  removed  in  the  hay  and 
seed  crops.  Observe  that  one  ton  of  raw  rock  phosphate  or  one 
ton  of  steamed  bone  meal  contains  more  phosphorus  than  100  tons 
of  average  manure.  Observe  that  250  pounds  of  phosphorus  can 
be  purchased  for  $7.50  in  ground  natural  rock  phosphate,  for  $25.00 

156 


SOURCES    OF   PLANT   FOOD 


in  steamed  bone  meal,  for  $30.00  in  acid  phosphate,  and  for  $65.00 
in  "  complete  "  fertilizer. 

TABLE  24.   FERTILITY  IN  MANURE,  ROUGH  FEEDS,  AND  FERTILIZERS 


NAME  OF  MATERIAL 

POUNDS  PER  TON 

MARKET  VALUE  PER  TON 

Ni- 
tro- 
gen 

Phos- 
phor- 
us 

Po- 
tas- 
sium 

Nitrogen 

Phos- 
phorus 

'otassium 

Total  Value 

Fresh  farm  manure  .     . 

IO 

2 

8 

$   1.50 

$      .24 

$    .48 

$    2.22 

Barnyard  manure  l    . 

IO 

3 

8 

1.50 

•36 

.48 

2-34 

Corn  stover      .... 

16 

2 

17 

2.40 

.24 

1.02 

3.66 

Oat  straw   

12 

2 

21 

1.80 

.24 

1.26 

3.-?o 

Wheat  straw    .... 

IO 

2 

18 

1.50 

.24 

1.08 

\J    tJ 

2.82 

Clover  hay       .... 

40 

5 

3° 

6.00 

.00 

i.  80 

8.40 

Cowpea  hay     .... 

43 

5 

33 

6-45 

.60 

1.98 

9-°3 

Alfalfa  hay       .... 

5° 

4 

24 

7-5° 

.48 

1.44 

9.42 

Dried  blood     .... 

280 

42.00 

42.00 

Sodium  nitrate      .     .     . 

310 

46.50 

46.50 

Ammonium  sulfate   .     . 

400 

60.00 

60.00 

Raw  bone  meal    .     .     . 

80 

180 

12.  OO 

iS.OO 

30.00 

Steamed  bone  meal  .     . 

20 

250 

3-00 

25.00 

28.00 

Acidulated  bone  meal   . 

40 

140 

6.00 

16.80 

22.80 

Raw  rock  phosphate 

250 

7-50 

7-5° 

Acid  phosphate    .     .     . 

125 

15.00 

15.00 

Double  superphosphate 

400 

48.00 

48.00 

Basic  slag  phosphate     . 

1  60 

16.00 

16.00 

Potassium  chlorid     .     . 

850 

51.00 

51.00 

Potassium  sulfate      .     . 

850 

51.00 

51.00 

Kainit     

200 

I2.OO 

I2.OO 

Wood  ashes  2  .     .     .     . 

10 

IOO 

i.  20 

6.00 

7.2O 

"Complete"  fertilizer3 

33 

88 

33 

(?) 

(?) 

(?) 

23.00  (?) 

1  About  two  tons  of  fresh  farm  manure  are  required  to  produce  one  ton  of  com- 
mon barnyard  manure  six  months  old,  with  losses  about  as  indicated. 

2  Wood  ashes  also  contain  about  1000  pounds  of  lime  (calcium  carbonate)  per 
ton. 

3  This  is  the  average  composition  and  the  average  selling  price  of  twelve  brands 
of  so-called  "complete"  fertilizer  offered  for  sale  in  Illinois.     Only  70  pounds  of 
the  phosphorus  is  guaranteed  available,  18  pounds  being  insoluble.     The  cost  of 
88  pounds  of  phosphorus  in  raw  rock  phosphate  would  be  $2.64. 


158  SCIENCE   AND    SOIL 

If  the  element  calcium  becomes  deficient  in  the  soil  (and  it  does 
in  some  cases),  the  most  economic  source  is  ordinary  limestone ; 
and,  if  magnesian  limestone  is  applied,  both  calcium  and  mag- 
nesium are  thus  added  to  the  soil.  Kainit  also  supplies  magnesium. 

Sulfur  would  be  furnished  in  applications  of  acid  phosphate, 
land-plaster,  potassium  sulfate,  or  kainit,  as  well  as  in  magnesium 
sulfate  and  sodium  sulfate,  both  of  which  are  sometimes  to  be  had 
as  waste  products  or  by-products. 

Iron  sulfate  (FeSO4)  is  a  common  by-product  in  certain  manu- 
facturing processes,  and  strenuous  efforts  have  been  made  from 
time  to  time  to  encourage  its  use  as  a  fertilizer.  Since  numerous 
investigations  have  been  conducted  both  in  Europe  and  America 
to  ascertain  its  fertilizing  value,  it  is  easily  possible  to  select,  from 
the  many  results  thus  secured,  some  few  which  indicate  appre- 
ciable or  even  marked  benefit.  These  results,  however,  have 
failed  of  verification.  As  a  general  average,  iron  sulfate  produces 
less  benefit  than  land-plaster,  and  sometimes  detrimental  effects 
are  shown.  A  fair  consideration  of  all  results  of  carefully  con- 
ducted experiments  certainly  leads  to  the  conclusion  that  the  use 
of  iron  sulfate  as  a  fertilizer  cannot  be  recommended  in  systems 
of  soil  improvement ;  although,  like  common  salt  (NaCl),  it  may 
sometimes  produce  a  stimulating  action  sufficient  to  cover  the  cost 
where  it  can  be  secured  at  less  expense  than  land-plaster,  common 
salt,  or  other  soluble  salts. 


PART  II 

SYSTEMS   OF   PERMANENT 
AGRICULTURE 

FOR  practically  all  of  the  normal  soils  of  the  United  States,  and 
especially  for  those  of  the  Central  states,  there  are  only  three  con- 
stituents that  must  be  supplied  in  order  to  adopt  systems  of  farm- 
ing that,  if  continued,  will  increase,  or  at  least  permanently 
maintain,  the  productive  power  of  the  soil.  These  are  limestone, 
phosphorus,  and  organic  matter.  The  limestone  must  be  used  to 
correct  acidity  and  sometimes  to  supply  the  element  calcium.  The 
phosphorus  is  needed  solely  for  its  plant-food  value.  The  supply 
of  organic  matter  must  be  renewed  to  provide  nitrogen  from  its 
decomposition  and  to  make  available  the  potassium  and  other 
essential  elements  contained  in  the  soil  in  abundance,  as  well  as 
to  liberate  phosphorus  from  the  raw  mineral  phosphate  naturally 
contained  in  or  applied  to  the  soil. 

Other  fertilizer  materials  have  some  value,  and  sometimes  great 
'value,  on  uncommon  or  abnormal  soils,  and  certain  other  substances 
are  powerful  soil  stimulants,  especially  on  soils  deficient  in  organic 
matter;  and,  if  applied  with  intelligence,  they  may  sometimes  be 
used  temporarily  with  advantage  and  justification,  but  they  are 
unnecessary  and,  as  a  very  general  rule,  they  are  unprofitable,  in 
good  systems  of  soil  improvement. 

There  are,  of  course,  numerous  and  more  or  less  extensive 
areas  of  abnormal  soils,  such  as  the  residual  sands  and  the  peaty 
swamp  lands  (both  of  which  are  very  deficient  in  potassium),  and 
also  soils  exceedingly  rich  in  phosphorus,  as  in  the  geologic  neigh- 
borhood of  the  natural  phosphate  deposits  in  the  Central  Basin  of 
Tennessee  and  the  Blue  Grass  Region  of  Kentucky. 

159 


CHAPTER  XII 

LIMESTONE 

CALCIUM  carbonate,  in  the  form  of  chalk  or  marl,  has  been  used 
for  soil  improvement  since  the  beginning  of  agricultural  history. 
Large  use  has  been  made  of  these  natural  materials  in  England  and 
France,  especially.  An  English  record  of  1795  mentions  the  "  pre- 
vailing practice  of  sinking  pits  for  the  purpose  of  chalking  the 
surrounding  land  therefrom,"  and  states  that  "  the  most  experi- 
enced Hertfordshire  farmers  agree  that  chalking  of  lands  so  circum- 
stanced is  the  best  mode  of  culture  they  are  capable  of  receiving." 

On  the  famous  Rothamsted  Experiment  Station  it  has  been  found 
that  the  fields  that  had  received  liberal  applications  of  this  natural 
limestone  a  century  ago  are  still  moderately  productive,  while 
certain  fields  remote  from  the  chalk  pits  which  show  no  evidence 
of  such  applications  are  extremely  unproductive.  Director  Hall 
of  the  Rothamsted  Experiment  Station  states  that  many  of  the 
farmers  in  that  vicinity  are  still  reaping  profitable  crops  from 
lands  enriched  by  the  heavy  applications  of  chalk  made  by  their 
ancestors  many  years  ago. 

There  appears  to  be  no  record  that  these  easily  pulverized  lime- 
stone materials  have  ever  been  burned  in  order  to  increase  their 
agricultural  value.  The  productive  power  and  durability  of  the 
natural  limestone  soils  is  indicated  by  the  time-honored  truth, 
"  A  limestone  country  is  a  rich  country." 

Where  such  natural  materials  as  chalk  and  marl  have  not  been 
accessible,  more  or  less  use  has  been  made  of  water-slacked  or  air- 
slacked  lime;  because,  by  burning  and  slacking,  limestone  rock  may 
be  reduced  to  powdered  form  and  thus  distributed  over  the  land. 

With  the  development  of  rock-crushing  and  rock-grinding 
machinery,  pulverized  natural  unburned  limestone  can  be  had, 
and  where  this  material  can  be  gotten  at  reasonable  cost,  it 
replaces  all  other  forms  of  lime  used  for  the  improvement  of  nor- 
mal soils. 

160 


LIMESTONE  161 

In  the  "  Georgical  Essays  "  (1777  edition),  we  find  an  article  by 
T.  Henry,  F.R.S.,  on  the  "  Action  of  Lime  and  Marl  as  Manures," 
in  which  the  following  statements  occur: 

"The  lime,  that  we  may  come  nearer  to  nature  in  our  imitation,  should  not 
only  be  slacked,  but  be  exposed  to  the  open  air,  and  often  turned  for  several 
months,  that  it  may  recover  its  air;  for  it  requires  a  long  series  of  time  be- 
fore it  recovers  the  whole  of  which  it  has  been  deprived  in  calcination 

"I  find  that  Doctor  Home  thinks  that  lime  produces  little  effect  on  vegeta- 
tion till  it  is  become  effete.  It  may  be  known  to  have  recovered  its  air  by  its  no 
longer  forming  lime  water,  and  by  effervescing  violently  with  acids  without 
growing  hot.  If,  however,  the  method  described  in  the  last  note  be  used,  it 
will  be  sufficient,  if  the  lime  be  fallen,  without  waiting  for  the  recovery  of  its 
air,  as  this  point  will  be  acquired  during  the  long  time  which  the  mixture  is  to 
be  exposed  to  the  action  of  the  atmosphere.  .  .  . 

"Upon  the  whole,  may  we  not  conclude  that  lime,  in  most  cases,  is  a  stronger 
manure,  when  it  has  recovered  the  air  of  which  it  has  been  deprived  in  calci- 
nation, than  it  is  when  brought  fresh  from  the  kiln ;  and  that  when  procured  for 
the  purposes  of  agriculture,  its  efficacy  and  permanency  will  in  general  be 
increased,  by  mixing  it,  in  its  effete  state,  with  the  other  ingredients  which  enter 
into  the  composition  of  marl?" 

-.  '  '  \  " 

When  limestone  is  burned,  the  calcium  carbonate  (CaCO3)  is 
decomposed,  the  carbon  dioxid  (CO2)  passes  off  as  a  gas,  leaving 
the  product  calcium  oxid  (CaO),  which  constitutes  56  per  cent  by 
weight  of  the  limestone  used. 

When  exposed  to  the  moisture  of  the  air  or  soil,  the  quicklime 
(CaO)  quickly  takes  up  water  and  forms  calcium  hydroxid, 
Ca(OH)2,  sometimes  called  hydrated  lime,  which  means  merely 
water-slacked  lime.  The  product  is  the  same  whether  the  slack- 
ing (hydrating)  is  performed  by  the  manufacturer  at  large  expense, 
or  by  the  farmer  at  little  or  no  expense. 

When  slacked  lime  is  exposed  in  the  air  or  soil,  carbon  dioxid  is 
gradually  absorbed,  and  the  calcium  carbonate  is  thus  reformed. 
Thoroughly  air-slacked  lime  is  exactly  the  same  material  as  fine- 
ground  limestone.  In  other  words,  no  matter  what  form  of  lime 
we  apply  to  the  soil,  the  benefit  derived  during  the  subsequent 
months  or  years  is  due  to  one  and  the  same  compound,  calcium 
carbonate. 

These  facts  alone  would  be  sufficient,  perhaps,  to  lead  one  to  use 
ground  natural  limestone  in  preference  to  the  disagreeable  caustic 


1 62        SYSTEMS   OF   PERMANENT   AGRICULTURE 

lime,  but  there  are  other  facts  worthy  of  the  most  careful  consid- 
eration. 

Burned  lime,  whether  fresh  or  hydrated,  is  known  always  as 
caustic  lime.  According  to  Webster's  Dictionary,  the  word  caustic 
means  "  capable  of  destroying  the  texture  of  anything  or  eating 
away  its  substance  by  chemical  action."  This  definition  well 
describes  the  action  of  caustic  lime  upon  the  organic  matter  of  the 
soil.  The  lime  breaks  down  the  organic  compounds  and  unites 
with  the  liberated  carbon  dioxid  or  other  acid  products.  Not  all 
of  the  reactions  involved  are  understood,  but  the  general  effect  is 
well  known,  and  its  long  recognition  in  European  countries  has 
given  rise  to  the  proverbial  expressions, 

"Lime,  and  lime  without  manure, 
Will  make  both  farm  and  farmer  poor," 

and  "  Kalk  macht  die  Vater  reich,  aber  die  Sohne  arm."  (Lime 
makes  the  fathers  rich,  but  the  sons  poor.) 

Caustic  lime  is  not  only  a  powerful  agent  in  hastening  the  de- 
struction of  organic  matter,  but  it  also  has  some  power  to  increase 
the  solubility  of  phosphorus  and  potassium,  all  of  which  may  be 
of  special  help  to  legume  crops;  and  if  such  crops  are  grown  and 
removed  from  the  land  and  the  decaying  roots  and  residues  used 
as  a  further  stimulant  for  the  production  of  wheat,  corn,  or  other 
crops,  more  rapid  progress  can  be  made  toward  land  ruin  than 
where  no  lime  is  used. 

On  the  other  hand,  even  caustic  lime  can  be  used  with  profit  if 
ample  provision  is  made  to  replace  the  organic  matter  destroyed 
and  also  to  restore  the  phosphorus  (and  potassium  if  necessary) 
removed  in  the  crops. 

The  caustic  action  of  slacked  lime  on  the  skin  or  flesh  is  familiar 
to  all,  but  a  child  can  play  in  ground  limestone  as  safely  as  in  the 
soil  of  the  garden. 

The  chief  reason,  and  usually  the  only  justifiable  reason,  for 
applying  lime  to  soils  is  to  correct,  or  neutralize,  soil  acidity.  The 
fermentation  and  decay  of  nearly  all  forms  of  organic  matter  is 
accompanied  by  the  formation  of  acids,  including  carbonic  acid, 
nitric  acid,  and  various  organic  acids,  such  as  the  well-known  lactic 
acid  of  sour  milk,  acetic  acid  of  vinegar  from  apple  juice,  various 


LIMESTONE  163 

acids  in  ensilage  and  sauerkraut,  etc.  Souring  is  usually  the  first 
stage  in  the  process  of  decay  of  organic  matter. 

Thus,  there  are  two  principal  effects  produced  by  applying  lime 
to  soils :  one  of  these  is  to  furnish  a  base  for  neutralizing  the  acids 
that  may  exist  in  the  soil  or  that  may  form  in  such  necessary 
processes  as  nitrification,  and  the  other  is  a  more  active  decomposi- 
tion or  destruction  of  the  soil  itself,  especially  of  its  organic  matter 
or  humus  content. 

To  correct  the  acidity  of  sour  soils  is  certainly  a  very  desirable 
and  profitable  use  of  lime.  Clover,  alfalfa,  alsike,  cowpeas,  soy- 
beans, and  most  other  valuable  legumes  will  not  thrive  on  soils 
that  are  strongly  acid.  To  be  sure,  such  crops  can  be  made  to  grow 
on  acid  soils  by  liberal  applications  of  farm  manure  or  other  fer- 
tilizers, but  the  nitrogen-gathering  bacteria  of  such  legume  plants 
do  not  properly  develop  and  multiply  in  acid  soils,  and  consequently 
the  legumes  do  not  have  the  power  which  they  should  have  to 
accumulate  large  quantities  of  atmospheric  nitrogen  by  means 
of  the  root-tubercle  bacteria.  Furthermore,  the  process  termed 
nitrification  by  which  the  nitrifying  bacteria  transform  the  in- 
soluble organic  nitrogen,  in  farm  manure  and  plant  residues,  into 
soluble  nitrate  nitrogen,  the  form  in  which  it  becomes  available 
as  plant  food,  is  greatly  promoted  by  the  presence  of  limestone  and 
retarded  by  acid  conditions. 

The  use  of  some  form  of  lime  for  correcting  the  acidity  of  soils, 
and  thus  encouraging  nitrification  and  the  growth  of  clover  and 
other  legumes  with  their  wonderful  power  to  enrich  the  soil  in 
nitrogen,  is  certainly  good  farm  practice.  Any  form  of  lime  which 
is  finely  divided  and  can  be  thoroughly  mixed  with  the  soil  will 
serve  this  purpose,  whether  it  be  ground  limestone,  marl,  or  chalk, 
or  fresh-burned  lime,  water-slacked  lime,  or  air-slacked  lime. 

The  one  effect  of  lime,  due  to  its  basic  property,  results  in  a 
building-up  process,  through  the  increased  growth  of  legumes  and 
nitrogen-gathering  bacteria;  while  the  other  effect,  the  decompo- 
sition of  the  soil,  produced  by  its  caustic  property,  is  in  all  respects 
a  destructive  process,  serving  only  to  destroy  humus  and  to  liber- 
ate and  reduce  the  stock  of  plant  food  stored  in  the  soil.  Whether 
this  second  effect  is  desirable,  will  depend  upon  the  soil  itself.  On 
soils  which  are  exceedingly  rich  in  organic  matter,  such  as  peaty 


1 64        SYSTEMS   OF   PERMANENT  AGRICULTURE 

soils  and  other  swamp  soils,  it  would  seem  altogether  rational  to 
make  temporary  use  of  caustic  lime  to  hasten  the  decomposition 
of  the  soil  and  consequent  liberation  of  nitrogen,  if  such  treatment 
is  necessary,  which  is  not  usually  the  case. 

There  may  possibly  be  conditions  under  which  soils  contain 
large  amounts  of  phosphorus  and  potassium  which  are  too  slowly 
available  for  profitable  crop  production,  and  in  such  cases  it  might 
be  good  farm  practice  for  a  time  to  make  use  of  lime  to  hasten 
the  liberation  of  these  mineral  elements  of  plant  food.  We  should 
bear  in  mind,  however,  that  this  use  of  lime  on  a  soil  which  is  already 
deficient  in  nitrogen,  or  other  plant  food,  only  serves  to  still  further 
exhaust  the  soil  of  its  meager  supply  of  these  elements.  Without 
a  doubt,  this  is  the  most  common  condition  and  the  most  common 
effect  of  the  continued  use  of  caustic  lime.  It  is  true  that  the 
immediate  effect  is  usually  somewhat  increased  crops,  but  it  should 
be  borne  in  mind  that  when  a  farmer  pays  out  money  for  lime  to  be 
used  for  this  purpose,  he  is  purchasing  a  stimulant  which  will  ulti- 
mately leave  his  land  in  worse  condition  than  before,  especially 
in  the  loss  of  nitrogen  and  organic  matter. 

Of  course,  the  landowner  must  be  governed  somewhat  by  the 
cost  of  the  material.  As  a  rule,  pulverized  limestone  will  be  both 
the  best  and  the  most  economical  form  of  lime  to  use,  wherever  it 
can  easily  be  obtained.  If  caustic  lime  be  used,  we  should  make 
special  provision  to  maintain  the  humus  in  the  soil  by  making 
even  larger  use  of  farm  manure,  legume  crops,  and  green  manures. 

It  might  be  expected  that  burned  lime  would  produce  a  greater 
increase  in  the  crops  for  the  first  year  or  two  than  would  be  pro- 
duced by  the  ground  limestone,  more  especially  where  the  mineral 
elements,  phosphorus  and  potassium,  are  not  applied;  for  the 
reason  stated,  that  ground  limestone  produces  only  the  milder  ac- 
tion, chiefly  of  correcting  the  acidity  of  the  soil  and  thus  encourag- 
ing the  multiplication  and  activity  of  the  nitrogen-gathering  and 
nitrifying  bacteria;  whereas,  the  burned  lime  not  only  produces 
this  same  effect,  but  it  also  acts  as  a  powerful  soil  stimulant,  or 
soil  destroyer,  attacking  and  destroying  the  organic  matter  and 
thus  liberating  plant  food  from  the  soil,  usually  resulting  in  more 
or  less  waste  of  valuable  nitrogen  and  humus. 

The  most  extended  investigation  ever  conducted  relating  to  the 


LIMESTONE 


use  of  burned  lime  and  ground  limestone  in  comparative  tests  is 
reported  by  the  Pennsylvania  Experiment  Station  (Report  1902). 
Four  plots  were  treated  with  burned  lime  (slacked  before  being 
spread)  at  the  rate  of  two  tons  per  acre  once  in  four  years.  Four 
other  plots  were  treated  with  ground  limestone  at  the  rate  of  two 
tons  per  acre  every  two  years.  A  four-year  rotation  was  practiced, 
consisting  of  corn,  oats,  wheat,  and  hay,  the  hay  being  mixed 
timothy  and  clover,  seeded  on  the  wheat  land  in  the  spring.  By 
having  four  sets  of  plots,  each  crop  was  grown  every  year.  Seven 
products  were  obtained  and  weighed  each  year;  namely,  corn, 
corn  stover,  oats,  oat  straw,  wheat,  wheat  straw,  and  hay. 

TABLE  25.   PENNSYLVANIA  EXPERIMENTS  WITH  BURNED  LIME  AND  GROUND 

LIMESTONE 

Twenty  Years'  Produce  per  Acre 


CORN 

OATS 

WHEAT 

HAY, 

Grain 

Stover 

Grain 

Straw, 

Grain 

Straw 

(19  yr-) 

(Bushels) 

(Tons) 

(Bushels) 

(Tons) 

(Bushels) 

(Tons) 

None       

8lQ 

18.8 

678 

14.3 

27O 

13.2 

24.0 

Burned  lime     .... 

699 

16.5 

6l7 

I7.8 

318 

14.6 

23.6 

Ground  limestone      .     . 

798 

18.6 

733 

20.4 

331 

16.6 

29.2 

Thus,  after  twenty  years'  results  had  been  obtained  (1882  to 
1901),  the  Pennsylvania  Station  reports  data  showing  that  with 
every  product  a  greater  total  yield  had  been  obtained  from  the 
plots  treated  with  limestone  than  from  those  treated  with  caustic 
lime.  Furthermore,  with  every  product  whose  total  yield  for  the 
last  eight  years  was  greater  than  the  total  yield  of  the  first  eight 
years,  the  limestone  produced  a  greater  increase  than  the  caustic 
lime;  and  with  every  product  whose  total  yield  for  the  last  eight 
years  was  less  than  the  total  yield  of  the  first  eight  years,  the 
decrease  was  less  where  limestone  was  used  than  where  caustic 
lime  was  applied  (oat  straw  alone  excepted).  This  is  significant, 
in  that  it  demonstrates  the  tendency  of  caustic  lime  with  continued 
use  to  exhaust  or  destroy  the  fertility  of  the  soil.  In  discussing 
these  investigations,  Doctor  Frear  of  the  Pennsylvania  Station 
says: 


1 66       SYSTEMS    OF   PERMANENT  AGRICULTURE 

"  In  each  case  the  yields  with  the  carbonate  of  lime  showed  superiority  under 
the  conditions  of  this  experiment  over  those  following  an  equivalent  application 
of  caustic  lime. " 

After  these  experiments  had  been  in  progress  for  sixteen  years, 
the  soil  of  each  of  the  four  plots  in  each  test  was  sampled  for  analy- 
sis. The  average  nitrogen  content  for  the  four  plots  receiving 
ground  limestone  was  found  to  be  2979  pounds  per  acre  to  a  depth 
of  9  inches,  while  only  2604  pounds  were  found  in  the  soil  treated 
with  caustic  lime.  This  difference  of  375  pounds  of  nitrogen  is 
equal  to  the  nitrogen  contained  in  37!  tons  of  farm  manure.  In 
other  words,  the  data  indicate  that  the  effect  of  caustic  lime  as 
compared  with  ground  limestone  was  equivalent  to  the  destruction 
of  37^  tons  of  farm  manure  in  16  years,  or  more  than  two  tons  a 
year  to  the  acre.  Or,  if  we  count  the  soil  nitrogen  worth  15  cents  a 
pound  (a  fair  market  price),  there  is  a  liberation  of  more  than 
$7.00  worth  of  nitrogen  for  every  ton  of  burned  lime  used  during 
the  1 6  years. 

The  estimation  of  humus  in  these  soils,  based  upon  the  determi- 
nation of  organic  carbon  (multiplied  by  Wolff's  factor,  1.724), 
showed  the  soil  receiving  limestone  to  contain  38.9  tons  of  humus 
per  acre  to  a  depth  of  9  inches  (counting  300,000  pounds  of  soil  to 
the  acre-inch),  while  only  34.2  tons  of  humus  remained  in  the  soil 
treated  with  caustic  lime.  If  4  tons  of  farm  manure  contain  only 
i  ton  of  dry  matter  (average  fresh  farm  manure  contains  about 
75  per  cent  of  water),  and  if  2  tons  of  dry  matter  would  be  re- 
quired to  make  i  ton  of  humus  (when  exposed  to  the  weather, 
manure  usually  loses  half  of  its  dry-matter  content  within  one 
year  or  less),  then  this  difference  of  4.7  tons  of  humus  would  be 
equal  to  37.6  tons  of  fresh  farm  manure,  which  represents  the  loss 
from  the  destructive  action  of  caustic  lime  as  compared  with 
ground  limestone. 

During  the  20  years,  the  land  treated  with  ground  limestone 
produced  per  acre  99  bushels  more  corn,  116  bushels  more  oats, 
13  bushels  more  wheat,  and  5.6  tons  more  hay,  than  the  land  treated 
with  caustic  lime.  Counting  35  cents  a  bushel  for  corn,  30  cents 
for  oats,  70  cents  for  wheat,  and  $6.00  a  ton  for  hay,  the  value  of 
the  produce  from  the  limestone  treatment  was  $112.15  more  than 
that  from  the  land  treated  with  caustic  lime.  The  total  ultimate 


LIMESTONE 


167 


effect  of  the  caustic  lime  for  the  20  years  was  an  actual  decrease 
in  the  yields  of  all  crops  except  wheat;  while  the  ground  limestone 
produced  an  increase  in  all  crops  except  corn,  on  which  the  de- 
crease was  only  one  sixth  as  much  as  with  caustic  lime. 

If  it  is  true,  as  indicated  by  the  Pennsylvania  experiments, 
that  8  tons  of  burned  lime,  applied  during  16  years,  released  375 
pounds  of  nitrogen  and  destroyed  organic  matter  equivalent  to 
37  tons  of  farm  manure,  or  more  than  $7.00  worth  of  nitrogen  and 
4^  tons  of  manure  destroyed  for  each  ton  of  burned  lime  used,  as 
compared  with  ground  limestone ;  and  if  larger  crops  were  obtained 
where  limestone  was  used,  especially  where  the  practice  is  extended 
over  several  years,  and  if  the  ground  limestone  is  sustaining  the 
productive  capacity  of  the  soil  much  better  than  the  burned  lime ; 
then,  as  a  very  general  rule,  we  should  avoid  applying  caustic 
lime  to  the  land,  but  make  liberal  use  of  ground  limestone  where 
needed  to  correct  the  acidity  of  the  soil  and  to  furnish  a  natural 
base,  although,  as  used  in  these  Pennsylvania  experiments,  without 
manure  and  with  no  return  of  plant  food,  the  increase  in  crop 
yields  produced  by  ground  limestone  has  not  been  sufficient  to 
pay  for  the  heavy  applications. 

The  Maryland  Experiment  Station  has  recently  reported  experi- 
ments with  different  kinds  of  lime,  covering  eleven  years,  with  a 
rotation  of  corn,  wheat,  and  hay  (timothy  and  clover),  1400  pounds 
of  calcium  oxid  (burned  lime)  and  equivalent  amounts  of  calcium 
carbonate  (ground  oyster  shells  and  shell  marl)  having  been  applied 
per  acre  at  the  beginning.  Four  crops  of  corn,  three  of  wheat,  and 
four  of  hay  were  harvested  during  the  eleven  years,  with  the  follow- 
ing total  results  per  acre: 

TABLE  25.1.   MARYLAND  EXPERIMENTS  WITH  LIME 


PRODUCE  IN  ELEVEN  YEARS 

KINDS  OF  LIME  USED 

Corn  (Bushels) 

Wheat  (Bushels) 

Hay  (Tons) 

4  Crops 

3  Crops 

4  Crops 

None     .     . 

08 

1.2 

2.6o 

Caustic  lime  burned  from  stone  '  .     . 

128 

32 

3-°9 

Caustic  lime  burned  from  shells  l  .     . 

129 

34 

3.82 

Calcium  carbonate  in  ground  shells 

148 

42 

3-97 

Calcium  carbonate  in  shell  marl  .     . 

145 

43 

4.29 

1  Average  of  two  plots. 


1 68       SYSTEMS    OF   PERMANENT    AGRICULTURE 

In  commenting  on  these  results,  Director  Patterson  of  the  Mary 
land  Experiment  Station  says:    "  It  will  be  noted  that  the  car- 
bonate of  lime  gave  decidedly  better  results  than  the  caustic  lime." 

Neuffer,  of  Heilbronn,  Germany,  has  published  a  book  entitled, 
"  Das  Kalksteinmehl  im  Dienste  der  Landwirtschaft "  (The  Use 
of  Ground  Limestone  in  Agriculture),  in  which  he  advises  that 
ground  limestone,  and  "  not  burned  lime,"  should  be  used  in  the 
improvement  of  soils  deficient  in  lime. 

Porter  and  Grant,  in  a  recent  Farmers'  Bulletin  issued  by  the 
Agricultural  Department  of  the  County  Council  of  Lancaster, 
England,  report  experiments  on  manured  and  unmanured  meadow 
lands,  showing  that  ground  limestone  is  more  profitable  as  an 
application  to  grass  lands  than  burned  lime,  and  that  it  can  be 
economically  used  on  grass  lands  which  are  in  need  of  lime. 

No  trustworthy  investigations  support  the  use  of  burned  lime 
in  preference  to  ground  limestone;  although  we  have  ample  in- 
formation showing  that  on  many  soils  a  moderate  use  of  burned 
lime  in  connection  with  a  liberal  use  of  farm  manure  and  green 
manures  yields  profitable  returns,  which  would,  no  doubt,  be  still 
more  profitable  if  the  burned  lime  were  replaced  with  ground 
limestone. 

The  most  abundant  impurity  of  limestone  is  magnesium  car- 
bonate, which  sometimes  occurs  in  equal  molecular  proportion  with 
calcium  carbonate,  in  what  is  called  dolomite  (CaCO3  MgCO3) . 
Limestones  containing  considerable  amounts  of  magnesium  car- 
bonate are  also  called  magnesian  limestones,  even  though  the 
proportion  of  magnesium  may  be  less  than  in  dolomite. 

Dolomitic  limestone  is  usually  slightly  heavier  than  ordinary 
limestone,  and  it  is  scarcely  attacked  by  cold  hydrochloric  or  acetic 
acid,  while  pure  calcium  carbonate  is  rapidly  decomposed,  the 
carbon  dioxid  being  liberated  as  a  gas. 

The  molecular  weights  are  100  for  calcium  carbonate  and  84  for 
magnesium  carbonate,  and  consequently  84  pounds  of  the  latter 
has  the  same  power  to  correct  soil  acidity  as  100  pounds  of  the 
former;  or  92  pounds  of  dolomite  will  correct  as  much  soil  acidity 
as  loo  pounds  of  pure  ordinary  limestone. 

To  determine  the  amount  of  limestone  present  in  the  soil,  or  to 
determine  the  value  of  a  sample  of  limestone  for  use  on  acid  soils, 


LIMESTONE  169 

it  is  usually  sufficient  to  determine  the  content  of  carbonate  carbon 
(or  carbon  dioxid)  and  compute  from  this  the  equivalent  amount 
of  calcium  carbonate.  Of  course,  this  computation  would  show 
that  100  pounds  of  pure  dolomite  would  be  equivalent  to  about 
109  pounds  of  pure  limestone. 

Agricultural  writers  have  placed  upon  record  the  general  opinion 
that  magnesian  lime  is  very  likely  to  produce  injurious  effects  when 
used  upon  the  soil. 

In  his  comprehensive  and  very  valuable  treatise  upon  "The 
Agricultural  Use  of  Lime,"  Doctor  William  Frear  includes  the  fol- 
lowing comments  (Report  Pennsylvania  State  College,  1899-1900, 
pages  14  to  176) : 

"Lloyd  states  that  lime  (CaO)  is  the  only  material  of  value  in  burnt  lime 
and  applies  the  adjective '  bad '  to  a  lime  containing  60  per  cent  of  lime  (CaO) 
and  30  per  cent  of  magnesia  (MgO).  Low  says  of  the  magnesian  limestone  of 
England:  'If  applied  after  being  calcined,  in  the  same  quantity  as  other  limes, 
it  produces  a  temporary  sterility,  burning,  as  it  were,  the  soil ;  hence,  it  is  termed 
hot  lime  and  is  applied  in  much  smaller  quantity  than  other  kinds  of  lime.' 
This  action  he  attributes,  after  Sir  Humphry  Davy,  to  the  longer  period  of 
causticity  commonly  supposed  to  occur  with  magnesia.  In  the  form  of  car- 
bonate, he  says,  'magnesia  seems  to  exercise  a  highly  favorable  action;  and 
magnesian  limestone  may  perhaps  be  regarded  as  the  most  valuable  of  any, 
since  a  smaller  quantity  of  it  suffices  for  the  ends  proposed.' 

"The  subject  is  quite  fully  discussed  by  Storer  (Agriculture,  1897,  Vol. 
2,  page  135),  who  notes  that  it  was  early  observed  by  English  chemists  that 
certain  limestones  which  had  sometimes  been  found  in  practice  to  injure  crops, 
contained  magnesia,  and  that  Tennant,  on  applying  calcined  magnesia  to 
various  soils  with  different  crops,  found  that  his  plants  either  died,  were  un- 
healthy, or  vegetated  very  imperfectly ;  also,  that  Knop  found,  in  growing  plants 
by  water  culture  (i.e.,  in  very  dilute  solutions  of  plant  foods),  that  magnesium 
salts  are  distinctly  harmful  unless  accompanied  by  abundance  of  lime,  potash, 
or  ammonia  salts;  by  themselves,  the  magnesium  salts  caused  peculiar  mal- 
formations of  the  plant  roots,  followed  shortly  by  the  death  of  the  plants. 

"Storer  notes,  on  the  other  hand,  that  Sir  Humphry  Davy  found  that  the 
very  magnesian  limestones  to  which  objection  was  made,  gave  very  beneficial 
results  on  certain  soils,  and  that  magnesia,  though  injurious  when  present  in 
caustic  condition  in  considerable  quantity  in  ordinary  soils,  may  be  beneficial 
when  mixed  with  peat  or  where  present  as  carbonate. " 

In  a  recent  investigation  at  Rothamsted,  Ashby  reports  a  larger 
fixation  of  nitrogen  by  Azotobacter  when  magnesium  carbonate 
was  present  than  when  calcium  carbonate  was  used.  For  each 


1 70       SYSTEMS    OF   PERMANENT   AGRICULTURE 

gram  of  carbohydrate  (mannite)  consumed,  8.92  milligrams  of 
nitrogen  were  fixed  in  6.6  days  with  magnesium  carbonate,  and 
5.80  milligrams  in  4.6  days  with  calcium  carbonate.  Ashby  says 
(Journal  of  Agricultural  Science,  January,  1907,  pages  46,  47) : 

"With  magnesium  carbonate  there  was  50  per  cent  more  nitrogen  fixed,  and 
a  delay  of  two  days  in  development.  .  .  .  One  must  conclude,  therefore,  the 
magnesium  carbonate  not  only  neutralizes  more  effectually  than  calcium  car- 
bonate any  trace  of  acidity  due  to  foreign  organisms  in  the  early  stages  of 
culture,  but  also  prevents  butyric  fermentation;  but  at  first  it  inhibits  the 
growth  of  Azotobacter  itself. " 

Table  26  gives  the  results  of  an  investigation  concerning  magne- 
sium carbonate  conducted  with  the  assistance  of  the  author's 
students  and  associates  at  the  University  of  Illinois.  The  experi- 
ment bears  upon  two  lines  of  inquiry —  (i)  the  value  of  magne- 
sium carbonate  for  soil  improvement,  and  (2) methods  of  correcting 
this  "  alkali"  when  present  in  injurious  amounts. 

Several  series  of  4-gallon  pots  were  filled  with  the  common 
brown  silt  loam  prairie  soil  from  the  University  farm,  and  to  five 
of  the  six  pots  in  each  series  was  added  magnesium  carbonate  in 
amounts  varying  from  .4  per  cent  to  2  per  cent  of  the  dry  soil. 
In  addition,  Series  C  and  F  received  calcium  sulfate  in  such  an 
amount  as  to  maintain  the  ratio  of  MgO  to  CaO  =  4  to  7,  in  ac- 
cordance to  Loew's  advocated  optimum  ratio. 

After  the  crop  of  1904  was  harvested,  the  pots  in  Series  F  were 
thoroughly  leached  in  order  to  remove  magnesium,  more  or  less 
of  which  was  expected  to  react  with  the  calcium  sulfate,  leaving 
the  harmless  calcium  carbonate. 

The  data  recorded  in  Table  26  show  a  distinct  and  persistent 
benefit  from  the  use  of  magnesium  carbonate  up  to  .8  per  cent  of 
the  soil,  while  with  1.2  per  cent  the  plants  are  very  seriously  injured 
and  with  1.6  per  cent  they  are  usually  so  nearly  killed  as  to  produce 
no  grain,  and  they  are  practically  all  killed  with  2  per  cent  of  mag- 
nesium carbonate. 

The  application  of  i  per  cent  of  magnesium  carbonate  would 
require  10  tons  per  acre  for  the  surface  6|  inches,  but  if  the  material 
were  applied  and  mixed  with  only  the  surface  inch  by  a  light  har- 
rowing, it  would  require  only  i|  tons  per  acre  for  i  per  cent. 
Since  pure  dolomite  would  contain  only  46  per  cent  of  magnesium 


LIMESTONE 


171 


TABLE  26.   ILLINOIS  POT-CULTURE  EXPERIMENTS 
Magnesium  Carbonate  in  Brown  Silt  Loam  Prairie  Soil 


POT 

"  ALKALI  "  APPLIED 

AMEND- 

ADDITIONAL 

YIELDS  OF  WHEAT  GRAIN, 
GRAMS  PER  POT 

No. 

MEN 

5 

Kind 

Cent 

1904 

1905 

1906 

1907 

1908  O. 

1908  R. 

SERIES  A:    MAGNESIUM  CARBONATE 

i 

None 

.O 

None 

None 

I5-23 

10.93 

11.50 

6.30 

8.60 

9.61 

2 

MgCOs 

•4 

None 

None 

21.  02 

10.97 

13.20 

9-35 

17.18 

19.18 

3 

MgCOs 

.8 

None 

None 

24.88 

12-57 

12.  60 

iQ-35 

8.16 

21.09 

4 

MgCOs 

1.2 

None 

None 

4-15 

9.02 

9.40 

14.00 

.00 

10.63 

5 

MgCO3 

1.6 

None 

None 

.00 

.00 

.10 

2.IO 

3-0° 

12.86 

6 

MgCOs 

2.0 

None 

None 

.00 

.00 

.00 

2.50 

.70 

2.72 

SERIES  C:    MAGNESIUM  CARBONATE  AND  CALCIUM  SULFATE 

i 

None 

.O 

None 

None 

11.22 

8.94 

12.20 

12.91 

8.00 

6.18 

2 

MgC03 

•4 

CaSO4 

None 

27.00 

12.02 

IO.OO 

8.79 

15.00 

16.32 

3 

MgCOs 

.8 

CaSO4 

None 

24.85 

*3-47 

I5-70 

8.42 

14.86 

21.15 

4 

MgC03 

1.2 

CaSO4 

None 

5-59 

11.25 

17.80 

IO.I8 

6.52 

22.50 

5 

MgCOs 

1.6 

CaSO4 

None 

.00 

2.03 

1.16 

8.58 

1.42 

11.98 

6 

MgCOs 

2.0 

CaSO4 

None 

.00 

.00 

•50 

6.68 

.62 

3-32 

SERIES  F :   MAGNESIUM  CARBONATE  AND  CALCIUM  SULFATE  —  LEACHED 


I 

None 

.0 

None 

None 

13.00 

8.51 

14.20 

6.67 

15.12 

17.40 

2 

MgC03 

•4 

CaSO4 

Leached 

17.12 

13.38 

11.40 

12.39 

12.72 

12.64 

3 

MgCOs 

.8 

CaSO4 

Leached 

22.35 

14.32 

8.30 

12.  60 

I3-50 

15.80 

4 

MgCOs 

1.2 

CaSO4 

Leached 

6.72 

14.18 

10.20 

16.66 

12.78 

14-57 

5 

MgC03 

1.6 

CaS04 

Leached 

3-73 

n-54 

II.  10 

10.75 

10.24 

I3-24 

6 

MgCOs 

2.O 

CaSO4 

Leached 

.00 

14-15 

10.70 

9-52 

10.22 

13.20 

1  Leached  after  1904. 

carbonate,  while  most  magnesian  limestones  contain  a  lower  per- 
centage, and  since  thorough  harrowing  or  disking  will  mix  the  ma- 
terial with  at  least  2  or  3  inches  of  soil,  there  is  no  likelihood  of 
any  but  beneficial  effects  from  initial  applications  of  5  or  6  tons 
to  the  acre,  and  subsequent  applications  of  2  tons  per  acre  every 
four  or  five  years  would  probably  never  produce  injury.  On  the 
other  hand,  it  is  highly  probable  .that  the  element  magnesium 


172       SYSTEMS    OF   PERMANENT   AGRICULTURE 

applied  in  dolomitic  limestone  may  produce  quite  as  much  benefit 
for  its  own  sake  as  will  the  element  potassium  on  most  soils  where  it 
proves  more  or  less  beneficial.  (The  limestones  in  Pennsylvania 
and  in  the  northern  parts  of  Ohio,  Indiana,  and  Illinois  are,  as  a 
rule,  more  or  less  magnesian,  containing,  as  an  average,  perhaps  30 
per  cent  of  magnesium  carbonate  and  60  per  cent  of  calcium  car- 
bonate, with  10  per  cent  of  impurities,  which  would  be  equivalent 
to  a  purity  of  95  per  cent  for  the  common  limestone.) 

As  an  experiment,  the  double  decomposition  and  leaching  proved 
a  success,  as  is  clearly  shown  in  Series  F,  pot  6  being  changed  from 
a  sterile  condition  to  as  productive  soil  as  any.  It  should  be  re- 
membered that  high  temperatures  may  occur  at  a  critical  period, 
and  consequently  seasonal  variations  are  marked  even  in  glass- 
house cultures.  Loew's  ratio  finds  little  support  from  these  data. 

Incidentally,  it  may  be  stated  that  during  the  progress  of  these 
experiments,  several  resistant  plants  have  developed,  wrhich 
explains  some  apparent  discrepancies  in  the  yields  of  wheat  from 
pots  near  the  border  line  of  injury;  and  consequently  the  seeds 
of  these  resistant  plants  have  been  used  in  part  throughout  one 
or  more  series.  In  1908,  one  half  of  each  pot  was  planted  with 
ordinary  (O.)  wheat,  and  the  other  half  with  the  resistant  (R.) 
strain,  and,  consequently,  double  the  weights  harvested  are  re- 
corded for  the  1908  yields. 

AMOUNT  OF  LIMESTONE  TO  APPLY 

From  the  information  thus  far  secured,  no  fixed  limits  can  be 
placed  upon  the  amounts  of  limestone  to  use  as  an  initial  applica- 
tion to  acid  soils.  One  ton  to  the  acre  is  more  than  enough  to 
destroy  the  acid  commonly  contained  in  the  plowed  soil,  provided 
the  limestone  is  sufficiently  fine  and  thoroughly  mixed  with  the 
soil;  but,  as  a  rule,  it  is  less  expensive  to  apply  more  limestone 
and  then  to  allow  the  mixing  to  go  on  more  slowly  by  the  neces- 
sary processes  of  plowing,  disking,  harrowing,  etc.,  in  the  regular 
farm  operations,  keeping  in  mind  also  that  the  heavier  the  appli- 
cation, the  longer  it  will  last. 

About  one  half  of  the  water  that  falls  in  rain  and  soaks  into  the 
soil  is  brought  back  to  the  surface  from  lower  depths  by  capillary 


LIMESTONE  173 

action  and  evaporated.  More  or  less  acidity  is  thus  brought  up 
from  the  acid  subsoil,  especially  in  time  of  drouth,  and  there  should 
be  sufficient  limestone  in  the  surface  to  destroy  this  acidity  as  it 
rises.  Quantitative  determinations  have  shown  that  to  correct 
the  total  acidity  contained  in  much  of  the  upland  soil  of  southern 
Illinois  to  a  depth  of  40  inches  would  require  more  than  10  tons 
of  limestone  per  acre. 

It  is  not  necessary  to  apply  such  amounts,  because  the  limestone 
does  not  descend  very  much  below  the  plowed  soil,  and  the  rise  of 
acidity  from  below  is  only  occasional  and  not  rapid. 

It  may  be  said,  however,  that  10  tons  of  ground  limestone  per 
acre  would  not  only  do  no  harm,  but  would  probably  produce 
somewhat  larger  crops  than  any  lighter  application.  As  much  as 
10  tons  per  acre  has  been  applied  on  an  experiment  field  in  southern 
Illinois,  and  the  crop  yields  on  that  field  have  been  larger  during 
the  last  three  years  than  on  any  other  experiment  field  in  that 
area.  Two  to  four  tons  per  acre,  however,  have  usually  produced 
much  benefit. 

The  author  has  used  2  to  3  tons  per  acre  of  magnesium  lime- 
stone on  his  own  southern  Illinois  farm  (gray  silt  loam  on  tight  clay), 
and  as  much  as  10  tons  per  acre  of  the  same  material  has  been 
used  on  another  farm  with  evident  benefit.  He  advises  an  appli- 
cation of  at  least  2  tons  of  ground  limestone  per  acre,  where  the 
addition  of  limestone  is  necessary,  believing  that  less  than  this  will 
not  give  satisfactory  results  in  practice.  Heavier  applications  will 
give  greater  profits  per  acre,  but  probably  less  profit  per  ton  of 
limestone  used. 

These  two  factors,  it  may  be  noted,  are  commonly  opposed  to 
each  other  in  many  farm  operations.  Thus,  farm  manure  gives  the 
greatest  profit  per  acre  in  heavy  applications,  but  the  greatest 
profit  per  ton  in  light  applications.  With  little  manure  and  much 
land  we  apply  the  manure  lightly,  but,  with  a  small  area  of  land 
and  large  supplies  of  manure,  we  apply  it  heavily.  So,  with  ground 
limestone:  If  one  must  cultivate  much  land  and  can  use  but  little 
limestone,  apply  2  tons  per  acre,  and  plan  to  apply  more  in 
later  years;  but,  if  one  cultivates  less  land  and  wishes  to  improve 
it  more  rapidly,  apply  4  to  10  tons  of  limestone  per  acre,  and 
it  will  give  more  marked  results  and  will  last  much  longer. 


174 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


The  amount  and  frequency  of  subsequent  applications  will  de- 
pend upon  the  rate  of  loss  by  leaching  and  by  removal  in  crops. 

The  soil  of  the  Rothamsted  Experiment  Station,  England,  is 
underlain  with  a  bed  of  calcium  carbonate,  in  the  form  of  chalk, 
at  a  depth  of  8  feet  or  more;  but,  nevertheless,  the  overlying  residual 
soil  material  is  normally  deficient  in  limestone  to  a  depth  of  several 
feet.  A  century  or  more  ago  certain  fields  were  given  heavy  appli- 
cations of  chalk,  dug  out  of  pits  excavated  for  the  purpose,  and  the 
fact  that  some  of  these  fields  still  contain  50  tons  of  calcium  car- 
bonate per  acre  in  the  plowed  soil  and  continue  to  produce  good 
crops,  with  fair  treatment,  is  proof  sufficient  that  there  is  no 
danger  of  applying  too  much  ground  limestone. 

During  a  period  of  40  years,  from  1865  to  1905,  large  numbers  of 
analyses  have  been  made  of  the  Rothamsted  soils.  During  that 
time,  according  to  Director  Hall  and  Doctor  Miller  (Proceedings  of 
the  Royal  Society,  1905,  Vol.  77),  there  have  been  the  following 
losses  of  calcium  carbonate  from  nine  different  plots  on  Broadbalk 
Field,  where  wheat  is  grown  every  year: 

TABLE   27.   LOSSES   OF   CALCIUM   CARBONATE   FROM   BROADBALK   FIELD, 
ROTHAMSTED,  FROM  1865  TO  1905 


PLOT 
No. 

SOIL  TREATMENT 

TONS  PER  ACRE 
IN  40  YEARS 

POUNDS  PER  ACRE 
PER  ANNUM 

2b 

Farm  manure-    

II.8 

CQO 

7 

Unmanured   

16  o 

800 

C 

Minerals    

176 

878 

6 

Minerals  and  single  ammonium  salts  . 

23-5 

1174 

7 

Minerals  and  double  ammonium  salts 

20.  2 

IOIO 

8 

Minerals  and  treble  ammonium  salts 

23-5 

1174 

9 

Minerals  and  single  nitrate  .... 

"•3 

564 

10 

Double  ammonium  salts       .... 

20.9 

1045 

ii 

Double   ammonium   salts   and   acid 

phosphate  

28.6 

14.20 

The  loss  of  calcium  carbonate  during  the  period  of  40  years 
ranges  from  11.3  to  28.6  tons  per  acre.  The  average  annual  loss 
where  ammonium  salts  have  been  applied  is  1170  pounds,  but  with 
no  ammonium  salts  the  average  loss  is  only  710  pounds  a  year,  or 
about  one  ton  per  acre  in  three  years. 


LIMESTONE 


From  eight  plots  on  Hoos  Field,  where  barley  is  grown  every 
year,  the  following  losses  of  calcium  carbonate  have  occurred: 

TABLE  28.   LOSSES  OF  CALCIUM  CARBONATE  FROM  Hoos  FIELD,  ROTHAMSTED, 
FROM  1865  TO  1905 


PLOT 
No. 

Son.  TREATMENT 

TONS  PER 
ACRE  IN 
40  YEARS 

POUNDS  PER 
ACRE  PER 
ANNUM 

Ol 

Unmanured      

22.7 

n8q 

O4 

Minerals      

14.  =! 

723 

Al 

Ammonium  salts  

IC..Q 

703 

A4 

Minerals  and  ammonium  salts    

is.o 

7  CO 

Ni 

Sodium  nitrate       

1^.4 

772 

N4 

Minerals  and  sodium  nitrate  

II.  I 

"^4 

Ci 

Rape  cake    

IS.O 

7">O 

7-2 

Farm  manure  

17.0 

848 

The  average  of  the  eight  plots  on  Hoos  Field  shows  for  40  years 
an  average  annual  loss  of  800  of  calcium  carbonate  per  acre.  The 
ammonium  salts  have  not  markedly  increased  the  average  loss  on 
this  field  above  that  from  the  nitrate  plots  or  the  untreated  land. 

The  investigations  reported  also  include  Agdell  Field  and  Little 
Hoos  Field,  both  of  which  have  lost  calcium  carbonate  in  about  the 
same  amount  as  Broadbalk  and  Hoos. 

Practice  based  upon  these  results  would  require  an  application 
of  two  tons  per  acre  of  ground  limestone  about  every  five  or  six 
years,  in  order  to  replace  the  regular  losses. 

The  loss  of  calcium  carbonate  from  soils  is  largely  due  to  leach- 
ing. The  soil  waters  contain  carbonic  acid  (H2COg)  formed  by  the 
absorption  of  carbon  dioxid  (CO2)  from  the  atmospheric  air  and 
from  the  soil  air.  This  carbonic  acid  has  power  to  react  with  cal- 
cium carbonate  and  form  calcium  bicarbonate,  .CaH2(CO3)2,  which 
is  soluble  in  water,  thus: 


H— O 

H— O\  / 

Ca^      >C=0  +  >C=0  =  Ca< 

TJ     r\s  \f 


>= 


O 


H— O' 


H— O 


=  O 


1 76        SYSTEMS    OF   PERMANENT   AGRICULTURE 

In  all  humid  regions  where  water  passes  through  the  soil,  there 
is  loss  of  calcium  carbonate,  leached  out  in  the  form  of  soluble 
bicarbonate.  The  "  lime  "  carried  in  solution  in  "  hard  "  waters 
from  surface  wells  appears  as  a  crust  or  scale  in  the  teakettle,  the 
soluble  bicarbonate  being  decomposed  by  heat  and  the  insoluble 
normal  carbonate  thus  precipitated.  Even  virgin  soils  in  old  soil 
formations  are  often  not  only  deficient  in  limestone,  but  they  are 
sometimes  found  to  be  exceedingly  acid,  and  thus  require  heavy 
applications  of  limestone  to  correct  or  neutralize  the  acids  in  the 
soil. 

Usually  these  soil  acids  exist  in  part,  at  least,  as  organic  acids 
(humic  acid  etc.),  but  it  is  very  evident  that  they  are  not  always 
entirely  organic,  because  the  acidity  often  markedly  increases  while 
the  organic  matter  decreases,  with  depth  of  soil,  as  will  be  seen 
from  Tables  15,  16,  and  17  (see  soil  types  330,  135,  and  335),  in 
which  the  measure  of  acidity  is  shown  by  the  "  limestone  required," 
and  the  organic  matter  is  indicated  roughly  by  the  nitrogen. 
Thus,  in  the  lower  Illinoisan  yellow  silt  loam,  limestone  required 
to  correct  the  acidity  increases  from  310  pounds  in  the  surface  to 
3315  pounds  in  the  subsurface,  and  to  7200  pounds  in  the  sub- 
soil, considering  2  million  pounds  of  each;  while  the  nitrogen  de- 
creases from  2150  pounds  in  the  surface  to  1085  pounds  in  the 
subsurface,  and  to  827  pounds  in  the  subsoil;  and,  as  a  matter  of 
fact,  the  organic  carbon  decreases  from  23,400  pounds  in  the  sur- 
face, to  9710  pounds  in  the  subsurface,  and  to  6190  pounds  in  the 
subsoil,  2  million  pounds  of  each  being  considered. 

Detmer  assigns  to  humic  and  ulmic  acids  the  molecular  formula 
C60H54O27,  and  to  their  salts  such  formulas  as  Ag8C60H46O27,  and 
Ca3(NH4)2C60H46O27.  These  would  correspond  to  Ca4C60H46O27. 
On  this  basis,  if  all  of  the  organic  carbon  in  the  subsoil  were  in  the 
form  of  humic  acid,  it  would  be  equal  to  less  than  one  half  of  the 
acidity  found.  These  computations  are  based  upon  the  average  of 
many  analyses  of  soil  samples  from  this  type.  Individual  samples 
show  as  high  as  six  times  as  much  acidity  as  could  be  accounted 
for  from  the  total  organic  carbon  if  in  the  form  of  humic  acid. 

Acid  silicates  .(see  acid  salts),  formed  from  polysilicates  (see 
under  silicon),  from  which  some  basic  elements  may  have  been 
removed  and  replaced  with  acid  hydrogen,  by  reaction  with  soluble 


LIMESTONE 


177 


organic  acids,  or  possibly  by  the  long-continued  weak  action  of 
drainage  waters  charged  with  carbonic  acid,  do  exist  in  the  soil, 
and  the  evidence  thus  far  secured  indicates  that  they  account  for 
most  of  the  acidity  of  soils  that  are  at  the  same  time  strongly  acid 
and  very  deficient  in  humus. 

Calcium  bicarbonate  may  be  formed  by  the  action  of  carbonic 
acid  on  silicates  containing  calcium,  even  though  no  limestone  is 
present.  It  is  well  known  that  plants  have  power  to  secure  calcium, 
as  plant  food,  from  acid  soils  containing  calcium  in  silicates  but 
not  containing  limestone. 

Of  course,  it  is  not  necessary  to  apply  limestone  to  soils  that 
already  contain  abundance  of  calcium  carbonate,  but  it  should  be 
applied  to  soils  that  show  acidity  in  the  top  soil  and  subsoil. 
Not  infrequently  slight  acidity  exists  in  the  surface,  and  sometimes 
in  the  subsurface  also,  where  the  subsoil  contains  very  large  amounts 
of  limestone.  From  present  information  we  cannot  strongly  advise 
the  application  of  limestone  to  such  soils,  although  it  would  cer- 
tainly do  no  harm,  and  for  some  crops  might  be  beneficial.  But 
where  the  subsoil  also  is  strongly  acid,  liberal  applications  of  lime- 
stone should  be  made.  While  a  small  amount  of  acidity  in  the  sur- 
face may  not  be  a  serious  injury  when  the  rainfall  is  abundant, 
there  is  apparently  in  humid  regions  some  rise  of  acidity  from 
strongly  acid  subsoils  in  times  of  partial  drouth,  corresponding 
somewhat  to  the  "rise  of  alkali  "  in  arid  regions,  where  the  water 
leaves  the  soil  only  by  evaporation  from  the  surface.  If,  however, 
the  subsoil  contains  abundance  of  limestone,  some  calcium  bi- 
carbonate will  be  brought  upward  into  the  subsurface  or  surface 
soil  with  the  capillary  rise  of  the  soil  moisture,  and  this  will  be  left 
as  normal  carbonate  when  the  water  evaporates,  and  may  serve  to 
reduce  the  acidity  of  the  subsurface  or  surface  soil,  at  critical 
times,  as  in  time  of  drouth. 

Clover  and  alfalfa  are  plants  that  are  very  sensitive  to  acid 
conditions  when  dependent  for  most  of  their  nitrogen  upon  the 
bacteria,  Pseudomonas  radicicola,  but  these  crops  are  grown  very 
successfully  upon  such  soils  as  the  brown  silt  loam  of  the  early 
Wisconsin  glaciation  and  the  brown  silt  loam, -yellow-gray  silt 
loam,  and  yellow  silt  loam,  of  the  late  Wisconsin;  whereas  they 
are  complete  failures  on  the  lower  Illinoisan  gray  silt  loam  prairie, 


178       SYSTEMS   OF   PERMANENT  AGRICULTURE 

and  very  unsatisfactory  crops  for  all  soils  with  strongly  acid  sub- 
soils, although,  as  already  stated,  such  crops  can  be  grown  for  a 
time  on  such  soils  if  liberally  fed  with  farm  manure  or  other  fer- 
tilizers. The  legume  plants,  themselves,  are  not  so  sensitive  to  acid 
conditions,  but,  rather,  the  bacteria  depended  upon  to  furnish 
nitrogen;  and  while  these  will  sometimes  live  and  even  form  tuber- 
cles, they  seem  to  develop  but  little  power  to  fix  nitrogen  under 
such  unfavorable  conditions. 

THE  TIME  TO  APPLY  LIMESTONE 

The  answer  to  this  question  can  be  no  more  definite  than  to  a 
similar  question  concerning  farm  manure.  We  should  consider 
the  matter  of  hauling  and  spreading  limestone  in  relation  to  the 
other  necessary  farm  work,  keeping  in  mind  conditions  of  weather, 
roads,  and  land.  It  is  applied  but  once  during  the  crop  rotation  and 
for  the  benefit  of  all  crops,  although  its  most  direct  benefit  is  for 
the  legumes,  the  other  crops  receiving  large  indirect  benefit  if  the 
legume  crops  are  returned  to  the  soil. 

It  is  sometimes  applied  in  winter  or  spring,  but,  as  a  rule,  it  is 
more  satisfactory  to  apply  it  during  the  summer  or  early  fall, 
when  the  land  is  dry,  the  roads  are  good,  and  the  days  are  long. 
It  is  not  best  to  apply  it  in  intimate  connection  with  phosphate, 
because  the  limestone  will  retard  the  availability  of  the  phosphorus, 
although  this  effect  is  temporary,  and  in  any  case  the  two  materials 
must  ultimately  become  mixed  if  applied  to  the  same  land.  The 
phosphate  may  well  be  applied  with  organic  matter  (manure  or 
clover),  mixed  with  the  surface  soil  by  disking,  and  then  plowed 
under,  and  the  limestone  may  then  be  applied  after  plowing  and 
well  mixed  with  the  surface  soil  in  the  preparation  of  the  seed  bed, 
where  wheat  and  clover  are  to  be  seeded,  or  where  corn  is  to  be 
followed  by  oats  and. clover,  the  oats  being  disked  in  without  re- 
plowing.  Thus  the  limestone  is  well  distributed  in  the  first  3  or  4 
inches  of  the  soil  where  the  atmospheric  nitrogen  enters  and  where 
the  nitrogen-fixing  bacteria  do  much  of  their  work,  while  the  phos- 
phate is  mixed  with  the  decaying  organic  matter  in  the  next  3  or  4 
inches  of  soil  where  the  plant  roots  feed  in  large  degree.  Another 
good  way  is  to  apply  the  phosphate  for  corn  and  the  limestone  for 
wheat  about  three  years  later. 


LIMESTONE  179 

METHODS  OF  APPLYING  LIMESTONE 

No  single  method  need  be  followed  in  applying  limestone  to  the 
land,  but  it  should  be  spread  as  evenly  as  practicable.  This  may  be 
done  by  hand  with  a  light  shovel,  either  from  the  wagon  or  from 
small  equal-sized  piles  placed  at  regular  intervals.  Thus,  a  pile  of 
100  pounds  every  33  feet  each  way  makes  two  tons  to  the  acre. 
It  can  easily  be  thrown  16  or  18  feet  with  a  shovel. 

A  spreader  made  for  the  purpose  of  applying  ground  limestone 
or  rock  phosphate  is  very  useful:  There  are  some  fairly  satisfactory 
machines  on  the  market  at  the  present  time.  Several  spreaders 
are  manufactured  that  serve  well  for  applying  ashes,  slacked  lime, 
or  other  light  materials,  but  most  of  them  are  not  suited  for  han- 
dling such  heavy  materials  as  limestone  and  rock  phosphate. 

The  directions  given  below  are  similar  to  those  published  by  the 
Ohio  Experiment  Station  for  a  "  home-made  "  spreader  which 
any  farmer  can  have  made,  and  which  is  more  satisfactory  for 
spreading  these  heavy  materials  than  some  of  the  machines  on  the 
market. 

Make  a  hopper  similar  to  that  o^an  ordinary  grain  drill,  measur- 
ing inside  8^  feet  or  n  feet  long  with  sides  about  21  inches  wide 
and  about  20  inches  apart  at  the  top.  The  sides  may  be  trussed 
with  -|-inch  iron  rods  running  from  the  bottom  at  the  middle  to 
the  top  at  the  ends  of  the  hopper.  Let  the  bottom  be  5  inches  wide 
in  the  clear,  and  cut  in  it  crosswise  a  row  of  diamond-shaped  holes, 
2  inches  wide,  2\  inches  long,  and  4  inches  apart  (6  inches  between 
centers).  Make  a  second  bottom  with  holes  in  it  of  the  same  size 
and  shape  as  those  of  the  main  bottom,  and  so  shaped  that  they 
will  register.  Let  this  second  bottom  slide  loosely  under  the  first, 
moving  upon  supports  made  by  leaving  a  space  for  it  above  bands 
of  strap  iron  12  inches  apart,  which  should  be  carried  from  one 
side  to  the  other  under  the  hopper  to  strengthen  it.  The  upper 
bottom  piece  may  be  of  about  8-inch  sheet  steel,  and  the  lower 
one  may  be  Of  smooth,  seasoned  hard  wood,  about  i  inch  thick 
and  7  inches  wide,  reenforced  with  strap  iron  if  necessary,  and 
well  oiled  or  painted.  To  this  under  strip,  attach  a  V-shaped  arm, 
extending  an  inch  in  front  of  the  hopper,  with  a  half-inch  hole  in 
the  point  of  the  V,  in  which  drop  the  end  of  a  strong  lever,  bolting 


i  So       SYSTEMS    OF   PERMANENT   AGRICULTURE 

the  lever  loosely  but  securely  to  the  side  of  the  hopper,  and  fasten 
to  the  top  of  the  hopper  a  guide  of  strap  iron,  in  which  the  lever 
may  move  freely  back  and  forth.  The  object  of  this  lever  is  to 
regulate  the  size  of  the  openings  by  moving  the  bottom  board. 
Make  a  frame  for  the  hopper,  with  a  tongue  to  it,  similar  to  the 
frame  of  an  ordinary  grain  drill. 

Get  a  pair  of  old  mowing-machine  wheels  with  strong  ratchets  in 
the  hubs,  and  with  pieces  of  round  axle  of  sufficient  length  to  pass 
through  the  frame  and  into  the  ends  of  the  hopper,  which  are  to 
be  welded  to  a  square  bar  of  iron  about  if  inches  in  diameter  and 
the  length  of  the  inside  of  the  hopper.  The  axles  should  be  fitted 
with  journals,  bolted  to  the  under  side  of  the  frame. 

Make  a  reel  to  work  inside  of  the  hopper  by  securing  to  the  axle, 
12  inches  apart,  short  arms  of  |-inch  by  i-inch  iron,  and  fastening 
to  these  arms  four  beaters  of  f-inch  square  iron,  about  an  inch 
shorter  than  the  inside  of  the  hopper,  the  reel  being  so  adjusted 
that  the  beaters  will  almost  scrape  the  bottom  of  the  hopper,  but 
will  revolve  freely  between  the  sides.  The  arms  may  be  made  of 
two  pairs  of  pieces,  bent  so  as  to  fit  around  the  axle  on  opposite 
sides,  and  secured  by  small  bolts  passing  through  the  ends  and 
through  the  beater,  which  is  held  between  them.  The  diameter  of 
the  completed  reel  is  about  5  inches,  and  it  serves  as  a  force  feed. 

Two  pieces  of  oilcloth  may  be  tacked  to  the  bottom  of  the 
hopper,  one  in  front  and  one  behind,  of  sufficient  width  to  reach 
nearly  to  the  ground,  in  order  to  reduce  the  annoyance  of  the  flying 
dust  to  man  and  team.  Another  piece  may  be  buttoned  across 
the  top  of  the  hopper  in  windy  weather,  if  desired;  but  the  dust  of 
limestone  or  of  natural  phosphate  is  certainly  no  worse  than  the 
dust  of  the  field. 

A  sort  of  second  force  feed  has  been  evolved  from  the  extensive 
experience  of  Illinois  farmers  in  building  home-made  machines: 
Two  pieces  of  sheet  steel,  each  about  6  inches  wide  and  the  length 
of  the  machine,  are  used  as  a  V-shape  bottom  for  the  hopper, 
forming  nearly  a  right  angle  at  the  lowest  point.  One  piece  is 
stationary  and  the  other  is  given  an  endwise  motion  back  and 
forth  by  means  of  a  small  wheel  with  a  heavy  rim  waving  in  and 
out  horizontally  and  running  through  a  slotted  piece  firmly 
attached  to  the  movable  sheet  steel.  Two  very  small  wheels 


LIMESTONE  181 

forming  the  sides  of  the  slot  serve  to  reduce  the  friction,  and  a 
lever  is  arranged  to  throw  this  mechanism  out  of  gear.  One  of  the 
pieces  of  sheet  steel  is  provided  with  an  adjustment  by  means  of 
which  a  crack  is  opened  of  any  desired  width,  the  entire  length  of 
the  bottom.  Thus  the  stone  falls,  not  through  holes  or  in  streaks, 
but  in  a  perfect  broadcast.  Several  of  these  home-made  machines 
are  in  use.  The  draft  is  more  than  with  the  reel  alone,  but  they 
are  undoubtedly  more  satisfactory  than  anything  on  the  market. 
The  cash  expense  for  such  a  machine,  aside  from  the  mower 
wheels  with  axle  and  ratchets,  has  varied  from  less  than  $10  to 
more  than  $20,  depending  on  cost  of  material  and  labor.  Farmers 
with  some  mechanical  skill  hire  only  the  necessary  blacksmithing. 

HINTS    ON   SPREADING    LIMESTONE    (AND    PHOSPHATE) 

In  hauling  and  spreading  limestone  it  is  of  first  importance  to 
save  time  and  labor.  As  a  rule,  it  is  more  economical  to  purchase 
both  limestone  and  raw  phosphate  in  bulk,  and  have  it  shipped 
in  paper-lined  box  cars.  Wetting  will  do  no  harm  except  to  give 
trouble  in  spreading.  Bags  are  expensive  and  easily  damaged, 
and  with  tight  wagon  boxes  the  use  of  bags  is  wholly  unnecessary. 
As  a  rule,  the  plan  should  be  to  haul  the  limestone  direct  from 
the  car  to  the  field,  and  spread  it  at  once.  Only  two  days  are 
allowed  to  unload  a  car,  although  an  extra  day's  car  service  costs 
only  one  dollar. 

With  a  haul  of  two  miles  or  less,  and  with  two  men,  one  boy,  and 
two  teams,  with  three  wagons  and  one  spreader,  30  tons  of  ground 
limestone  can  be  taken  from  the  car  and  spread  over  10  to  15  acres 
of  land  in  two  or  three  days,  provided  the  roads  and  other  condi- 
tions are  favorable. 

One  man  is  kept  in  the  car  loading  the  limestone  into  a  wagon. 
The  boy  with  one  team  hauls  the  loaded  wagon  to  the  field,  leaves 
it  there,  and  takes  an  empty  wagon  back  to  the  car,  hitching  at 
once  to  the  loaded  wagon  and  leaving  the  empty  wagon  to  be  loaded. 
The  other  man  and  team  remain  in  the  field  with  the  spreader, 
spreading  one  load  while  the  boy  is  gone  for  the  next.  If  an  extra 
team  is  at  hand,  the  man  at  the  car  may  drive  to  meet  the  empty 
wagon  and  thus  save  some  time. 


182       SYSTEMS    OF   PERMANENT  AGRICULTURE 

When  spreading  across  a  forty-acre  field,  the  loaded  wagon 
should  either  be  hauled  to  the  middle  line  of  the  field,  or  half  of  the 
loads  should  be  hauled  to  one  side  and  the  other  half  to  the  oppo- 
site side  of  the  field,  using  an  extra  wagon.  The  spreader  hopper 
should  hold  at  least  1000  pounds  on  the  half-rod  machines,  or  1333 
pounds  on  the  n-foot  machines,  so  that  by  driving  80  rods,  the 
load  will  amount  to  at  least  two  tons  per  acre.  Starting  from  the 
middle  of  the  field,  one  hopperful  will  spread  to  the  side  (40  rods) 
and  back,  when  the  spreader  must  be  backed  up  to  the  wagon  and 
refilled.  Four  such  drives  (320  rods)  with  the  half-rod  machine,  or 
three  drives  (240  rods)  with  the  n-foot  machine,  will  spread  a 
two-ton  load  over  an  acre. 

If  the  roads  are  good,  two  tons  can  be  hauled  at  a  load  with  a 
good  team  and  wagon.  If  necessary  to  draw  the  loaded  wagon  to 
the  middle  line  of  the  field,  a  four-horse  team  is  provided  by  adding 
the  spreader  team. 

For  making  applications  from  one  half  ton  to  two  or  three  tons 
per  acre  of  limestone  or  rock  phosphate,  an  arrangement  of  this 
sort  is  very  satisfactory.  For  heavier  applications  one  can  go  over 
the  ground  twice,  or  it  can  be  spread  by  hand.  For  longer  dis- 
tances, one  or  more  additional  teams  are  needed  on  the  road. 

Where  manure  is  to  be  spread,  rock  phosphate  may  well  be  spread 
with  it.  The  phosphate  may  be  sprinkled  over  the  manure  from 
day  to  day  as  it  is  being  made  in  the  stall  or  covered  feeding  shed, 
or  the  manure  spreader  may  be  partly  filled  with  manure,  phosphate 
then  being  sprinkled  on  sufficient  for  the  load,  the  load  com- 
pleted, and  then  spread  on  the  land.  It  should  be  kept  in  mind, 
however,  that,  if  any  leaching  occurs  after  the  phosphate  is  mixed 
with  the  manure  and  before  the  manure  is  spread  on  the  land,  some 
loss  may  ensue  of  the  added  phosphate;  while  if  the  phosphate  is 
taken  directly  from  the  car  and  spread  on  the  land  where  manure 
has  been  or  is  to  be  applied,  it  can  later  be  plowed  under  with  the 
manure  with  no  danger  of  loss  of  phosphate. 

NOTE.  Limestone  is  soluble  in  soil  water  containing  carbonic  acid,  and  if 
ground  to  pass  a  sieve  with  about  10  meshes  to  the  linear  inch,  it  is  sufficiently 
fine,  provided  the  product  contains  all  of  the  finer  material.  Fineness  correlates 
with  loss  by  leaching  as  well  as  with  "  availability,"  while  the  coarser  particles 
are  more  durable  and  serve  as  centers  of  alkalinity.  (See  pages  174,  198,  561.) 


CHAPTER  XIII 

PHOSPHORUS 

PHOSPHORUS  is  the  only  element  that  must  be  purchased  and 
returned  to  the  most  common  soils  of  the  United  States.  Phos- 
phorus is  the  key  to  permanent  agriculture  on  these  lands.  To  main- 
tain or  increase  the  amount  of  phosphorus  in  the  soil  makes  pos- 
sible the  growth  of  clover  (or  other  legumes)  and  the  consequent 
addition  of  nitrogen  from  the  inexhaustible  supply  in  the  air; 
and,  with  the  addition  of  decaying  organic  matter  in  the  residues 
of  clover  and  other  crops  and  in  manure  made  in  large  part  from 
clover  hay  and  pasture  and  from  the  larger  crops  of  corn  and  other 
grains  which  clover  helps  to  produce,  comes  the  possibility  of 
liberating  from  the  immense  supplies  in  the  soil  sufficient  potas- 
sium, magnesium,  and  other  essential  abundant  elements,  supple- 
mented by  the  amounts  returned  in  manure  and  crop  residues, 
for  the  production  of  large  crops  at  least  for  thousands  of  years; 
whereas,  if  the  supply  of  phosphorus  in  the  soil  is  steadily  de- 
creased in  the  future,  in  accordance  with  the  past  and  present  most 
common  farm  practice,  then  poverty  is  the  only  future  for  the 
people  who  till  the  common  agricultural  lands  of  the  United  States. 

And  this  does  not  refer  to  the  far-distant  future  only,  for  the 
turning  point  is  already  past  on  most  farms  in  our  older  states  and 
on  many  farms  in  the  corn  belt ;  and  lands  that  have  passed  their 
prime  with  sixty  years  of  cultivation  will  decrease  rapidly  in  pro- 
ductive power  and  value  during  another  sixty  years  of  similar 
exhaustive  farm  practice. 

The  world's  supply  of  phosphorus  exists  in  three  principal 
sources:  First  are  the  supplies  in  the  various  soils,  concerning 
which  the  reader  of  the  preceding  pages  will  have  sufficient  posi- 
tive knowledge  for  intelligent  thought. 

Second  are  the  natural  beds  of  calcium  phosphate,  varying  in 
purity  from  a  few  per  cent,  to  as  high  as  80  per  cent,  of  tricalcium 
phosphate,  Ca3(PO4)2. 

183 


1 84       SYSTEMS    OF   PERMANENT   AGRICULTURE 

Third  are  the  extensive  deposits  of  phosphatic  iron  ores  con- 
taining more  or  less  ferric  phosphate,  FePO4,  the  phosphorus  being 
recovered  in  the  slag  produced  in  the  conversion  of  pig  iron  into 
steel. 

About  three  fourths  of  the  phosphorus  taken  from  the  soil  by 
crops  of  corn,  wheat,  or  other  cereals,  is  deposited  in  the  grain  or 
seed,  about  one  fourth  remaining  in  the  straw  or  stalks.  If  the 
grain  is  sold,  three  fourths  of  the  phosphorus  required  for  the  crop 
is  sold  with  it;  and,  likewise,  when  grain  is  bought  and  brought  to 
the  farm,  a  like  proportion  of  phosphorus  is  brought  with  it. 

When  crops  are  fed  to  animals,  as  a  general  average  about 
three  fourths  of  the  phosphorus,  three  fourths  of  the  nitrogen, 
and  practically  all  of  the  potassium  are  returned  in  the  manurial 
excrements.  Thus,  if  sufficient  grain  is  bought  and  fed,  and  if  the 
manure  is  saved  and  applied  to  the  land,  the  soil  can  be  made  richer 
in  phosphorus  year  by  year,  and  in  most  sections  some  instances 
can  be  found  of  farmers  who  succeed  in  maintaining  or  increasing 
the  fertility  of  their  soil  by  this  practice.  If  they  have  the  neces- 
sary knowledge  and  skill  and  material  equipment  and  sufficient 
capital,  they  may  feed  stock  for  the  open  market,  or  if  this  is  not 
profitable,  they  may  produce  pure-bred  stock  to  sell  at  higher  prices 
for  breeding  purposes.  In  any  case,  live-stock  farming  can  never 
be  permanently  profitable  to  a  large  proportion  of  the  farmers 
in  a  great  agricultural  country,  because  the  world  cannot  live  on 
meat  and  dairy  products  only,  and  the  relative  supply  and  demand 
always  compels  the  sale  of  much  grain  from  most  farms.  Conse- 
quently, this  system  of  adding  phosphorus  to  one  farm  by  taking 
it  from  other  farms  must  be  of  limited  application;  and  live-stock 
farmers  who  feed  only  the  produce  from  their  own  land  gradually 
reduce  the  phosphorus  of  the  soil  at  least  by  the  amount  sold  in 
the  animal  products. 

A  still  more  limited  supply  of  phosphorus  is  secured  for  use  in 
soil  improvement  by  utilizing  the  bone  meal  prepared  by  the  pack- 
ing houses.  This,  of  course,  also  comes  from  the  soil  originally. 
It  is  made  chiefly  from  bone  scraps  which  have  no  value  for  other 
uses.  The  best  bone  is  worth  several  times  as  much  for  the  manu- 
facture of  buttons,  cutlery,  toilet  articles,  etc.,  as  for  fertilizer 
purposes.  Probably  not  more  than  one  tenth  of  all  the  phos- 


PHOSPHORUS  185 

phorus  shipped  off  from  American  farms  in  animal  products  is 
returned  to  the  soil  in  bone  fertilizers.  The  mineral  matter  in  bone 
consists  chiefly  of  tricalcium  phosphate,  with  a  small  amount  of 
calcium  carbonate.  There  is  practiced  more  or  less  adulteration 
of  bone  fertilizers  by  admixture  of  raw  rock  phosphate  or  acid 
phosphate. 

There  are  three  principal  forms  of  bone  meal'offered  for  sale — 
(i)  raw  bone,  (2)  steamed  bone,  and  (3)  acidulated  bone. 

Raw  bone  meal.  Raw  bone  meal  contains  about  9  per  cent  of 
phosphorus,  4  per  cent  of  nitrogen,  and  much  organic  matter, 
including  more  or  less  fat,  which  tends  to  retard  decomposition. 
The  most  common  application  of  bone  or  other  ordinary  commercial 
fertilizer  is  200  pounds  per  acre.  Since  9  per  cent  means  9  pounds 
per  hundred,  this  application  would  amount  to  18  pounds  of 
phosphorus  per  acre,  or  one  pound  more  than  is  contained  in 
100  bushels  of  corn.  Since  200  pounds  is  one  tenth  of  a  ton,  raw 
bone  meal  contains  about  180  pounds  of  phosphorus  per  ton. 

Hence,  the  rule:  To  convert  per  cent  into  pounds  per  ton, 
double  the  per  cent  and  add  one  cipher.  It  is  always  advisable  to 
memorize  pounds  per  ton  and  to  think  in  those  amounts,  rather 
than  in  per  cent.  At  10  cents  a  pound  for  phosphorus  and  15 
cents  for  nitrogen,  a  ton  of  raw  bone  meal  costs  about  $30,  which  is 
$18  for  the  phosphorus  and  $12  for  the  nitrogen. 

Nearly  i|  tons  of  raw  bones  are  required  to  make  one  ton  of 
steamed  bones,  the  loss  in  weight  consisting  of  fat,  flesh,  glue,  and 
other  organic  matters  rich  in  nitrogen. 

Steamed  bone  meal.  Steamed  bone  meal  contains  from  12 
to  14  per  cent  of  phosphorus,  and  it  should  average  at  least  12^ 
per  cent,  or  250  pounds  of  phosphorus  per  ton,  costing  $25  at 
10  cents  a  pound  for  the  element  phosphorus.  Thus,  200  pounds 
of  steamed  bone  per  acre  supplies  25  pounds  of  phosphorus,  or 
two  pounds  more  than  is  required  for  a  hundred-bushel  crop  of 
corn  (grain  and  stalks).  By  steaming  bones  the  nitrogen  is  largely 
removed  in  the  organic  matter,  only  about  .8  per  cent,  or  16  pounds 
per  ton,  being  found  in  good  steamed  bone,  an  amount  within  the 
legal  limits  of  error  in  some  fertilizer  laws,  and  too  small  to  justify 
consideration  in  the  purchase  price,  especially  when  nitrogen  can 
be  secured  from  the  inexhaustible  supply  in  the  air  by  using  leg- 


1 86       SYSTEMS   OF   PERMANENT   AGRICULTURE 

umes  in  crop  rotations.  To  supply  sufficient  nitrogen  for  a  hun- 
dred-bushel crop  of  corn  would  require  9  tons  of  steamed  bone 
meal,  costing  about  $225. 

The  phosphorus  in  raw  bone  and  steamed  bone  exists  in  the  form 
of  the  insoluble  tricalcium  phosphate,  but  because  of  the  porosity 
and  fine  division  of  the  bone  particles  and  the  presence  of  decom- 
posing organic  matter  in  intimate  contact  with  the  extensive  sur- 
face within  the  pores,  phosphorus  is  liberated  quite  readily  from 
bone  meal,  steamed  bone  being  more  active  because  of  the  removal 
of  the  fat  and  because  it  is  usually  more  finely  ground  than  raw 
bone. 

Acidulated  bone  meal.  Acidulated  bone  meal  ("  acid  bone ") 
is  made  by  adding  to  a  ton  of  bone  meal  sufficient  sulfuric  acid  to 
convert  a  part  of  the  insoluble  tricalcium  phosphate  into  the  sol- 
uble monocalcium  phosphate,  or  at  least  into  the  more  readily 
available  dicalcium  phosphate.  The  bone  meal  thus  treated  is  said 
to  be  mildly  acidulated.  As  an  average,  it  contains  about  140 
pounds  of  phosphorus  and  40  pounds  of  nitrogen  per  ton.  Much 
of  the  so-called  "  dissolved  bone  "  sold  in  the  fertilizer  trade  is  made 
from  phosphate  rock,  and  this  is  no  detriment  to  the  product  so 
far  as  the  soluble  portion  is  concerned,  but  the  insoluble  portion 
is  more  rapidly  available  if  derived  from  bone  than  from  rock. 
In  the  acidulated  and  most  readily  available  form,  phosphorus 
sells  at  about  12  cents  a  pound. 

Other  bone  products  include  bone  black,  dissolved  bone  black, 
and  bone  ash.  Tankage  from  the  packing  houses  varies  from 
nearly  pure  bone  to  a  high  percentage  of  nitrogenous  organic 
matter,  including  dried  blood,  meat,  and  mixed  offal.  Some  further 
data  will  be  found  under  nitrogen  fertilizers. 

Three  principal  kinds  of  phosphorus  fertilizer  are  derived  from 
phosphate  rock.  These  are  (i)  the  fine-ground  natural  rock, 
(2)  acid  phosphate,  and  (3)  double  superphosphate. 

Natural  phosphates.  Natural  phosphate  beds  are  widely  dis- 
tributed over  the  earth,  some  of  the  most  important  deposits  being 
in  Tennessee,  South  Carolina,  Florida,  and  Canada,  also  in  France, 
Belgium,  Norway,  Spain,  and  North  Africa.  The  present  annual 
production  of  the  world  amounts  to  about  three  million  tons,  of 
which  two  million  tons  are  produced  in  the  United  States,  about 


PHOSPHORUS  187 

one  million  for  home  consumption,  and  an  equal  amount  for 
exportation,  chiefly  to  Great  Britain,  Germany,  and  other  parts 
of  Europe. 

It  is  estimated  that  the  total  phosphate  deposits  of  the  world 
thus  far  discovered  will  still  furnish 'somewhere  from  200  million 
to  500  million  tons  of  high-grade  phosphate  rock.  Some  phosphate 
deposits  have  recently  been  found  in  Wyoming,  Idaho,  and  Utah, 
and  doubtless  still  other  extensive  deposits  will  be  discovered  in 
various  parts  of  the  earth;  but,  nevertheless,  the  world's  total 
supply  of  high-grade  phosphate  is  apparently  very  limited  when 
measured  by  crop  requirements,  as  evidenced  by  the  enormous 
shipment  of  phosphate  from  America  to  Europe,  despite  the  exten- 
sive and  long-continued  search  by  geologists  for  any  undiscovered 
European  deposits.  (See  also  Appendix.) 

Facts  worthy  of  careful  consideration  are  that  the  Chilian  gov- 
ernment derives  a  large  revenue  from  export  duties  on  sodium 
nitrate,  from  the  world's  greatest  natural  deposits  of  combined 
nitrogen,  an  element  which  the  Chilian  landowners  can  always 
secure,  however,  from  the  inexhaustible  atmospheric  supply; 
whereas,  from  the  United  States  we  are  exporting  half  of  our  total 
production  of  phosphates  with  no  restrictions,  although  we  are 
thus  shipping  away  from  our  lands  the  only  element  we  shall  ever 
need  to  purchase  in  order  to  maintain  the  fertility  of  our  own  soils. 
The  laws  of  Norway  greatly  restrict  the  exportation  of  phosphate 
from  that  country. 

To  restore  to  the  soils  of  the  United  States  the  phosphorus 
removed  by  the  corn  crop  alone,  would  require  the  annual  applica- 
tion of  our  total  annual  production  of  phosphate  rock,  counting 
23  pounds  of  phosphorus  for  a  hundred-bushel  crop  of  corn,  and 
2\  billion  bushels  as  the  average  corn  crop  of  the  United  States. 

The  Florida  phosphates  are  classed  chiefly  as  hard  rock  and  soft 
rock,  the  South  Carolina  phosphates  as  land  rock  and  river  rock; 
and  the  Tennessee  phosphates  as  brown  rock  and  blue  rock.  The 
quality  is  usually  expressed  as  percentage  of  purity;  that  is, 
percentage  of  tricalcium  phosphate. 

The  South  Carolina  land  rock  is  the  lowest  in  phosphorus,  averag- 
ing less  than  50  per  cent  calcium  phosphate,  or  less  than  10  per  cent 
of  phosphorus.  The  South  Carolina  river  rock  and  the  Florida 


1 88       SYSTEMS   OF   PERMANENT  AGRICULTURE 

soft  rock  average  50  to  60  per  cent  pure;  while  the  Florida  hard 
rock  and  the  Tennessee  brown  rock  contain  from  60  to  75  per  cent 
of  calcium  phosphate.  The  Tennessee  blue  rock  varies  from  less 
than  50  to  more  than  70  per  cent,  or  from  200  to  300  pounds  of 
phosphorus  per  ton  of  rock.  The  Florida  soft  rock  contains  chiefly 
phosphates  of  iron  and  aluminum,  while  in  the  other  rocks  the 
phosphorus  is  largely  in  the  form  of  tricalcium  phosphate. 

Aside  from  the  deposits  of  high-grade  phosphate,  containing 
45  or  50  to  75  or  80  per  cent  of  calcium  phosphate,  there  are  known 
to  exist  very  much  more  extensive  deposits  of  lower  grade  phos- 
phates and  phosphatic  limestones  containing  from  less  than  10 
per  cent  to  40  per  cent  or  more  of  calcium  phosphate,  correspond- 
ing to  from  2  to  8  per  cent  of  phosphorus,  or  from  40  to  160  pounds 
of  phosphorus  per  ton  of  rock.  At  present,  these  deposits  have  no 
market  value,  because,  if  the  phosphate  costs  $4.00  per  ton  fine- 
ground  and  on  board  cars  at  the  mine,  and  if  the  freight  charges 
are  $3.00  per  ton,  the  freight  on  two  tons  of  low-grade  rock  would 
amount  to  $6.00;  while  the  delivered  cost  of  one  ton  of  high-grade 
rock  supplying  the  same  amount  of  phosphorus  would  be  only 
$7.00,  leaving  but  50  cents  a  ton  for  the  low-grade  rock,  which  would 
barely  pay  for  the  expense  of  easy  quarrying  and  grinding. 

As  the  supplies  of  high-grade  phosphate  become  exhausted  and 
prices  advance,  the  lower  grades  will  no  doubt  be  utilized  in  this 
country  as  they  are  in  Europe,  where  35  to  40  per  cent  Belgian 
phosphate  is  now  one  of  the  chief  commercial  grades. 

About  62^  per  cent  calcium  phosphate,  or  \2\  per  cent  of  phos- 
phorus, is  the  average  grade  of  the  fine-ground  natural  rock  phos- 
phate now  used  in  Illinois,  and  to  some  extent  in  other  states,  for 
direct  application  to  the  soil  in  intimate  connection  with  abundance 
of  decaying  organic  matter,  as  farm  manure,  clover,  or  other  green 
manures.  In  this  form  the  element  phosphorus  costs  the  farmer 
about  3  cents  a  pound. 

The  information  thus  far  secured  amply  justifies  the  adoption 
of  a  system  of  farming  in  which  fine-ground  natural  phosphate 
rock  should  be  applied  at  the  rate  of  1000  to  2000  pounds  per  acre 
every  three  to  six  years,  for  three  or  four  successive  crop  rotations, 
after  which  the  application  may  be  reduced  one  half,  or  to  200 
pounds  per  acre  for  each  year  in  the  rotation,  which  would  still 


PHOSPHORUS 


insure  a  small  increase  rather  than  a  decrease  in  the  future1 
years. 

More  specific  data  concerning  the  use  of  raw  rock  phosphate, 
the  results  of  the  most  careful  experiments,  and  the  comparative 
value  of  different  forms  of  phosphorus  are  more  fully  discussed 
in  the  following  pages,  after  some  consideration  of  organic  matter. 

Acid  phosphate.  Acid  phosphate  is  the  name  of  a  manufactured 
product,  not  of  a  chemical  compound. 

Chemically,  there  are  two  acid  phosphates  of  calcium,  (i)  the 
monocalcium  phosphate,  CaH4(PO4)2,  and  (2)  the  dicalcium  phos- 
phate, Ca2H2(PO4)2.  These  chemical  compounds,  together  with 
tricalcium  phosphate  and  tetracalcium  phosphate,  phosphoric  acid, 
phosphorus  pentoxid,  and  phosphorus,  itself,  form  a  very  impor- 
tant and  interesting  series.  For  the  sake  of  simplicity  and  uni- 
formity, two  atoms  of  phosphorus  are  given  in  each  case,  this  being 
necessary  in  some  cases: 


NAME 

FORMULA 

MOLEC- 
ULAR 
WEIGHT 

PHOS- 
PHORUS 
(Per  Cent) 

Phosphorus    

P2 

62 

IOO.OO 

Phosphorus  pentoxid    .     .     .     . 

P2O5 

142 

4"?.  66 

Phosphoric  acid  

H6(PO4)2 

1  06 

31.63 

Monocalcium  phosphate  .... 
Dicalcium  phosphate   

CaH4(PO4)2 
Ca2H2(PO4), 

234 

272 

26.50 

22.43 

Tricalcium  phosphate  

Cas(PO4)2 

3IO 

20.00 

Tetracalcium  phosphate   .... 

Ca3(CaO)(P04)2 

366 

16.94 

Of  these  substances,  tricalcium  phosphate  is  the  only  one  that 
occurs  in  nature.  The  element  phosphorus  takes  fire  when  exposed 
to  the  air,  two  atoms  of  phosphorus  uniting  with  five  atoms  of 
oxygen  to  form  phosphorus  pentoxid,  sometimes  called  phosphoric 
oxid.  This  compound  is  the  most  powerful  dehydrating  agent 
known  in  chemistry,  having  power  to  abstract  water  from  many 
other  substances.  It  unites  with  water  to  form  true  phosphoric 
acid,  H3PO4,  or  H6(PO4)2.  This  is  one  of  the  strong  acids,  and  if  it 
comes  in  contact  with  calcium  carbonate,  for  example,  it  takes  up 
one,  two,  and,  finally,  three  bivalent  atoms  of  calcium  in  place  of 
the  univalent  hydrogen  atoms,  and  thus  forms  acid  monocalcium 


I  go       SYSTEMS   OF   PERMANENT  AGRICULTURE 

phosphate,  acid  dicalcium  phosphate,  or  the  neutral  tricalcium 
phosphate,  respectively,  carbonic  acid  being  liberated,  which 
promptly  decomposes  into  water  and  the  gas,  carbon  dioxid. 

Tetracalcium  phosphate  is  thought  by  some  to  be  the  compound 
in  which  phosphorus  exists  in  basic  slag  phosphate,  being  essen- 
tially tricalcium  phosphate  loosely  united  with  the  CaO  group 
(see  under  basic  slag  phosphate). 

In  the  manufacture  of  commercial  acid  phosphate,  the  phosphorus 
material  most  commonly  used  in  mixed  commercial  fertilizers,  one 
ton  of  ground  raw  rock  phosphate  is  treated  with  about  one  ton  of 
sulfuric  acid,  and  the  resulting  material  consists  chiefly  of  mono- 
calcium  phosphate  and  calcium  sulfate  (land-plaster),  together 
with  all  of  the  impurities  contained  in  the  original  materials,  and 
this  mixture  is  the  ordinary  acid-phosphate  fertilizer: 

Ca3(PO4)2  +  2  H2SO4  =  CaH4(PO4)2  +  2  CaSO4. 

This  equation  shows  only  the  general  reaction  between  the 
chemical  compounds,  tricalcium  phosphate  and  sulfuric  acid,  but 
impurities  are  always  present,  and  both  the  impurities  and  the 
calcium  sulfate  are  included  in  acid  phosphate,  in  which  the  phos- 
phorus is  held  chiefly  in  the  water-soluble  compound,  monocalcium 
phosphate.  The  reaction  may  be  expressed  in  two  equations,  the 
two  molecules  of  sulfuric  acid  being  added  separately,  thus  showing 
dicalcium  phosphate  as  an  intermediate  product.  Small  amounts 
of  both  dicalcium  phosphate  and  tricalcium  phosphate  usually 
remain  in  acid  phosphate,  and  a  considerable  part  of  the  sulfuric 
acid  used  reacts  with  impurities  which  consist  chiefly  of  silicates 
of  the  abundant  metals,  aluminum,  iron,  calcium,  magnesium, 
potassium,  and  sodium.  Sometimes  calcium  carbonate  is  among 
the  impurities.  As  a  rule,  about  one  fourth  of  acid  phosphate 
consists  of  phosphates  (chiefly  monocalcium  phosphate),  while 
three  fourths  consist  of  calcium  sulfate  and  impurities. 

The  readily  available  phosphorus  in  acid  phosphate  has  a  market 
value  of  about  12  cents  a  pound.  This  includes  the  phosphorus 
soluble  in  water  and  also  that  dissolved  by  ammonium  citrate 
solution,  which  is  sometimes  called  the  "  citrate-soluble  "  or  the 
"  reverted."  The  term  reverted  is  properly  applied  to  dicalcium 


PHOSPHORUS  191 

phosphate  formed  from  monocalcium  phosphate  by  reaction  with 
tricalcium  phosphate: 

CaH4(P04)2  +  Ca3(P04)2  =  2  Ca^PO,),. 

On  long  standing,  this  sort  of  reaction  evidently  takes  place  if  an 
excess  of  tricalcium  phosphate  was  left  in  the  original  product,  and 
consequently  the  percentage  of  water-soluble  phosphorus  may  be 
greater  in  fresh  acid  phosphate  than  in  that  which  has  been  stored 
for  some  time,  the  dicalcium  phosphate,  or  "  reverted,"  being  sol- 
uble in  citrate  solution,  but  not  in  water. 

If  the  raw  phosphate  rock  contains  12  per  cent  of  phosphorus, 
the  acid  phosphate  made  from  it  will  contain  about  6  per  cent  of 
phosphorus.  The  most  common  grade  is  known  as  14  per  cent  acid 
phosphate,  which  the  fertilizer  agent  would  say  means  that  the 
acid  phosphate  con  tains  14  per  cent  of  "  phosphoric  acid,"  by  which, 
however,  is  meant  not  14  per  cent  of  true  phosphoric  acid,  H3PO4, 
but  14  per  cent  of  phosphorus  pentoxid,  P2O5,  which  is  equivalent 
to  6.1  per  cent  of  the  element  phosphorus,  corresponding  to  122 
pounds  of  phosphorus  per  ton  of  acid  phosphate,  which  sells  at 
about  $15  a  ton. 

Where  250  pounds  of  phosphorus  cost  $7.50  in  fine-ground 
natural  rock  phosphate,  the  same  amount  of  phosphorus  will 
usually  cost  $30  in  the  two  tons  of  acid  phosphate.1 

Double  superphosphate.  Double  superphosphate  consists  chiefly 
of  monocalcium  phosphate,  CaH4(PO4)2,  and  a  moderate  amount  of 
impurities.  It  is  richer  in  phosphorus  than  any  other  fertilizer 
material.  It  is  made  (i)  by  treating  low-grade  phosphate  rock 
with  an  excess  of  sulfuric  acid,  by  which  true  liquid  phosphoric 
acid  is  liberated.  This  is  leached  out  of  the  mass,  and  (2)  this  true 
phosphoric  acid  is  applied  to  high-grade  phosphate  rock,  thus: 

(1)  Ca3(P04)2  +  3  H2S04  =  H6(P04)2  +  3  CaSO4; 

(2)  Ca3(P04)2  +  2  H6(P04)2  =  3  CaH4(P04)2. 

1  Both  acidulated  bone  and  acid  phosphate  are  sometimes  called  superphos- 
phate; and  in  England  "super"  (meaning  literally  over  or  higher)  is  the  common 
term  for  acid  phosphate,  somewhat  as  photographers  use  the  term  "hypo"  (mean- 
ing under  or  lower)  for  sodium  thiosulfate,  formerly  incorrectly  called  hyposulfite 
of  soda. 


SYSTEMS   OF   PERMANENT   AGRICULTURE 

By  this  means  the  impurities  of  the  low-grade  phosphate  and 
the  calcium  sulfate  formed  in  the  first  reaction  are  left  behind,  and 
the  monocalcium  phosphate  is  then  formed  as  a  condensation  prod- 
uct, with  only  the  impurities  of  the  high-grade  phosphate  and  a 
small  amount  of  calcium  sulfate  made  from  the  excess  of  sulfuric 
acid  which  is  carried  with  the  phosphoric  acid.  In  practice,  double 
superphosphate  is  made  to  contain  about  20  per  cent  of  the  ele- 
ment phosphorus,  corresponding  to  about  75  per  cent  of  mono- 
calcium  phosphate,  and  to  400  pounds  of  phosphorus  per  ton  of 
product.  This  material  is  not  made  in  the  United  States,  but  is 
produced  to  a  considerable  extent  in  Germany.  It  has  advantage 
over  ordinary  acid  phosphate  in  long-distance  shipping,  and  it  also 
permits  the  use  of  phosphate  rock  containing  more  iron  and  alumi- 
num than  can  be  used  for  the  manufacture  of  common  acid  phos- 
phate on  account  of  the  deliquescent  properties  of  the  products. 

Slag  phosphate.  Basic  slag  phosphate  results  as  a  by-product 
when  pig  iron,  made  from  phosphatic  iron  ores  and  thus  contain- 
ing considerable  phosphorus,  is  converted  into  steel  by  the  basic 
process  in  which  an  excess  of  lime  is  used.  By  proper  methods  a 
slag  is  produced  which  may  contain  about  8  per  cent  of  phosphorus, 
or  160  pounds  per  ton.  It  is  commonly  held  that  the  phosphorus 
is  in  the  form  of  tetracalcium  phosphate,  Ca4O(PO4)2,  whose  struc- 
tural composition  might  be  represented  thus: 

Tetracalcium  Tricalcium  Phosphoric 

phosphate  phosphate  acid 


Ca—  O-)P=O 


/ 
>°  Ca< 

H 


Ca 


H—  cr 

Whether  these  formulas  express  the  relationship  of  tetracalcium 
phosphate  to  tricalcium  phosphate  and  to  phosphoric  acid,  is  not 
fully  known,  and  it  is  even  questioned  if  the  phosphorus  in  basic 


PHOSPHORUS  193 

slag  exists  in  the  form  of  tetracalcium  phosphate.  However,  an 
excess  of  calcium  oxid  is  present,  and  the  phosphorus  in  slag  under 
suitable  conditions  can  be  made  available.  No  doubt,  the  lime 
produces  some  benefit  for  its  own  sake  on  certain  classes  of  soil. 
In  value,  the  phosphorus  is  rated  at  10  cents  a  pound,  the  same  as 
in  bone  meal. 

The  iron  ores  from  the  Lake  Superior  region,  which  are  used  in 
the  Illinois  Steel  Works,  contain  too  small  an  amount  of  phosphorus 
to  give  value  to  the  slag  produced,  but  some  phosphorus-bearing 
ores  are  used  in  Pennsylvania,  and  slag  phosphate  has  been  pro- 
duced and  used  in  that  state  to  a  limited  extent  for  several  years. 

In  Europe  very  large  quantities  of  slag  phosphate  are  produced 
and  sold  under  the  name  of  Thomas  slag,  although  Jacob  Reese, 
who  for  many  years  controlled  the  production  in  Pennsylvania, 
claimed  priority  over  the  European  discovery. 

The  conditions  under  which  the  different  forms  of  phosphorus 
should  be  used  are  discussed  in  the  following  pages. 


CHAPTER  XIV 

ORGANIC   MATTER   AND    NITROGEN 

THE  organic  matter  of  the  soil  may  be  considered  in  two  classes, 
active  and  inactive,  although  no  very  sharp  line  can  be  drawn 
between  them. 

The  most  active  organic  matter  consists  of  such  substances  as 
decaying  plant  roots  and  crop  residues,  green  manures  and  animal 
manures,  incorporated  with  the  soil.  These  products  decay  rapidly 
in  the  soil  and  in  the  process  of  decomposition  liberate  not  only 
plant  food  which  they  contain,  including  nitrogen,  phosphorus, 
and  potassium,  but  they  also  set  free  other  decomposition  products, 
such  as  carbonic  acid,  nitric  acid,  and  organic  acids,  which  have 
power  to  dissolve  more  or  less  additional  plant  food  from  the 
mineral  part  of  the  soil. 

The  inactive,  or  less  active,  organic  matter  consists  of  the  more 
resistant  organic  residue  that  remains  after  several  years  and  that 
decomposes  very  slowly.  If  present  in  large  quantity,  its  gradual 
decomposition  may  still  supply  sufficient  nitrogen  to  meet  the 
needs  of  good  crops,  although  its  power  to  liberate  mineral  plant 
food  from  the  soil  may  not  provide  adequate  supplies  of  available 
phosphorus,  potassium,  etc. 

Thus,  we  find  that  one  soil  may  at  the  same  time  be  richer  in 
organic  matter  and  less  productive  than  another  soil,  even  though 
the  two  soils  are  alike  in  other  respects.  Three  tons  per  acre  of 
fresh,  actively  decaying  organic  matter  may  be  more  effective 
for  a  year  or  two  than  thirty  tons  of  old  and  less  active  humus. 

The  term  humus  is  not  synonymous  with  organic  matter. 
Humus  includes  only  that  part  of  the  organic  matter  that  has 
passed  the  most  active  stage  of  decomposition  and  completely  lost 
the  physical  structure  of  the  materials  from  which  it  is  made,  and 
has  thus  become,  as  a  rule,  thoroughly  incorporated  with  the  soil 
mass. 

194 


ORGANIC   MATTER   AND    NITROGEN  19$ 

It  is  the  decay  of  organic  matter,  and  not  the  mere  presence  of  it, 
that  gives  "  life  "  to  the  soil.  Partially  decayed  peat  produces  no 
such  effect  upon  the  productive  power  of  the  soil  as  follows  the 
use  of  farm  manure  or  clover  residues. 


DECAY  OF  ORGANIC  MATTER 

A  matter  that  has  led  to  much  confusion  and  misunderstanding 
is  the  common  talk  of  "  available  plant  food,"  as  distinct  from  the 
total  supply,  whereas  there  is  no  line  of  distinction.  The  question 
as  to  the  amount  of  available  plant  food  contained  in  the  soil  at 
any  given  time  is  very  insignificant  in  comparison  with  the  ques- 
tion how  to  make  plant  food  available.  The  plant  food  removed 
from  the  soil  by  a  crop  is  not  available  when  the  crop  is  planted, 
but  it  must  be  made  available  during  the  growing  season. 

Plant  food  is  made  available  by  chemical  and  biochemical 
processes,  of  which  ammonification  and  nitrification  are  among 
those  best  understood. 

For  the  exact  information  we  now  have  regarding  these  processes, 
we  are  indebted  to  the  researches  of  Pasteur  and  Schlosing  and 
Miintz  of  France,  Winogradsky  of  Russia,  Warington  of  England, 
and  others.  The  nitrogen  in  the  soil  is  almost  entirely  in  organic 
compounds;  that  is,  the  nitrogen  is  united  or  combined  with 
other  elements,  notably  carbon,  hydrogen,  and  oxygen,  with 
small  amounts  of  phosphorus,  and  sulfur,  in  the  form  of  partially 
decayed  organic  matter;  but  plants  cannot  use  these  insoluble 
organic  compounds  of  nitrogen  occurring  in  the  soil. 

There  are  at  least  three  different  kinds  of  microscopic  organisms 
(called  bacteria),  and  also  three  different  steps,  or  stages,  involved 
in  the  process  of  nitrification,  the  nitrogen  being  changed  from  the 
organic  compounds,  first  into  the  ammonia  l  form  (NH3) ,  second 
into  the  nitrite  form,  as  Ca(NO2)2,  and  third,  into  the  nitrate 
form,  as  Ca(NO3)2.  During  the  process  the  nitrogen  is  separated 
from  the  carbon  and  other  elements  composing  the  insoluble  or- 
ganic matter,  and  is  united  or  combined  with  oxygen  and  some  alka- 
line element  to  form  the  soluble  nitrate,  such  as  calcium  nitrate, 

1  Technically  this  first  step  (ammonification)  is  preliminary  to,  and  not  a  part 
of,  nitrification  proper. 


196        SYSTEMS    OF   PERMANENT  AGRICULTURE 

which  is  one  of  the  most  suitable  compounds  of  nitrogen  for  plant 
food. 

This,  then,  is  the  general  process  of  nitrification  (including  am- 
monification  and  nitrification  proper) ,  in  which  the  ammonifying 
and  nitrifying  bacteria  transform  or  transfer  the  nitrogen  from 
insoluble  organic  compounds  into  soluble  nitrate  compounds  in 
which  it  may  serve  as  available  plant  food.  Each  specific  class  of 
bacteria  performs  a  distinct  function.  Thus,  the  ammonifying  bac- 
teria serve  only  to  convert  organic  nitrogen  into  ammonia  nitrogen; 
the  nitrite  bacteria  (also  called  nitrous  bacteria)  serve  only  to 
convert  ammonia  nitrogen  from  ammonia  or  ammonium  salts 
into  nitrous  acid  (HNO2)  or  nitrites;  and  the  nitrate  bacteria 
(also  called  nitric  bacteria)  serve  only  to  convert  nitrous  acid  or 
nitrites  into  nitric  acid  (HNO3)  or  nitrates. 

While  we  may  assume  that  the  nitrogen  passes  through  the  forms 
of  nitrous  and  nitric  acid,  those  acids  are  never  present  in  detectable 
quantities,  the  presence  of  a  salifiable  base  being  essential  for  the 
progress  of  these  biochemical  reactions.  The  final  product  is  al- 
ways a  nitrate,  except  under  artificial  conditions,  when  nitrites 
may  be  obtained  in  quantity  in  the  absence  of  the  nitrate  bacteria. 
Under  the  natural  conditions  existing  in  normal  soils,  even  nitrites 
can  scarcely  be  detected,  because  of  the  quickness  with  which  they 
are  converted  into  nitrates. 

The  nitrate  that  is  formed  may  be  calcium  nitrate,  magnesium 
nitrate,  potassium  nitrate,  sodium  nitrate,  or  even  ammonium 
nitrate,  depending  upon  which  base  is  present  in  the  most  suitable 
form.  In  the  nitrification  of  ammonium  carbonate,  (NH4)2CO3, 
the  reaction  will  stop  when*  only  one  half  completed  if  no  other 
base  is  present,  the  final  product  being  ammonium  nitrate, 
NH4NO8. 

(NH4)2  CO3  +  3  O  =  NH4NO2  +  CO2  +  2  H2O. 
NH4NO2  +     O  =  NH4NO3. 

To  continue  the  process  beyond  this  point  would  require  the 
formation  of  appreciable  amounts  of  free  nitric  acid,  of  which  the 
bacteria  seem  incapable.  In  the  production  of  lactic  acid  in 
the  souring  of  milk,  the  lactic  bacteria  are  capable  of  continuing  the 


ORGANIC   MATTER  AND  •  NITROGEN  197 

process  until  the  solution  contains  about  .7  per  cent  of  free  lactic 
acid,  beyond  which  they  become  inactive;  but,  if  the  free  lactic 
acid  is  neutralized  by  the  addition  of  some  base,  the  bacteria  again 
become  active. 

In  the  process  of  nitrification  there  is  required,  not  only  the 
presence  of  calcium  or  some  other  alkaline  element  or  group,  in 
suitable  form  (as  in  carbonates) ,  but  also  a  good  supply  of  the  ele- 
ment oxygen;  for  calcium  nitrate  contains  but  one  atom  of  calcium 
(Ca)  with  two  atoms  of  nitrogen  (N)2,  and  six  atoms  of  oxygen 
(O3)2,  in  each  molecule,  as  indicated  in  the  formula  Ca(NO3)2. 
Magnesium  nitrate,  Mg(NO3)2,  potassium  nitrate,  KNO3,  and  all 
other  nitrates  also  contain  oxygen.  The  supply  of  oxygen  for  the 
formation  of  nitrates  in  the  process  of  nitrification  comes  from  the 
air,  and,  aside  from  the  killing  of  weeds,  one  of  the  most  important 
effects  of  cultivation,  or  tillage,  is  that  it  permits  the  air  more 
freely  to  enter  the  soil,  and  thus  promotes  nitrification. 

Another  absolute  requirement  for  the  process  of  nitrification  is 
the  presence  of  phosphorus  and  probably  of  other  mineral  food 
supplies  necessary  to  the  growth  and  multiplication  of  the  bacteria 
themselves.  It  is  known  that  without  phosphorus  there  can  be 
neither  growth  nor  life.  These  minute  forms  of  plant  life  do  not 
utilize  the  carbon  dioxid  of  the  air  by  means  of  the  sun's  energy; 
but  they  derive  energy  from  the  oxidation  of  the  nitrogen  com- 
pounds, and  by  means  of  this  energy  they  are  able  even  to  decom- 
pose carbonates,  if  necessary,  and  to  derive  their  supply  of  carbon 
from  this  source  for  the  formation  of  their  own  organic  bodies; 
but  for  all  of  this  the  mineral  plant  food  must  be  supplied.  (As  a 
rule,  the  carbohydrates  furnish  the  necessary  carbon  for  bacterial 
growth.) 

An  important  consideration  in  this  general  connection  is  the 
fact  that  in  the  conversion  of  sufficient  organic  nitrogen  into  nitrate 
nitrogen  for  a  hundred-bushel  crop  of  corn,  the  nitric  acid,  if 
formed,  would  be  alone  sufficient  to  convert  seven  times  as  much 
insoluble  tricalcium  phosphate  into  soluble  monocalcium  phosphate 
as  would  be  required  to  supply  the  phosphorus  for  the  same  crop. 
While  this  specific  reaction  could  not  occur  in  quantity,  because 
the  acid  monocalcium  phosphate  would  prevent  nitrification,  the 
suggestion  is  of  interest  in  that  it  affords  a  quantitative  comparison 


ig8       SYSTEMS   OF   PERMANENT  AGRICULTURE 

between  one  of  the  decomposition  products  of  organic  matter  and 
the  process  of  making  insoluble  plant  food  available,  thus: 

Ca3(P04)2  +  4HN03  =  CaH4(P04)2  +  2  Ca(NO3)2. 

In  accordance  with  this  equation,  56  parts  of  nitrogen  are  equiva- 
lent to  62  parts  of  phosphorus  in  the  reaction;  whereas,  when 
measured  by  the  requirements  of  the  corn  crop,  56  parts  of  nitro- 
gen are  equivalent  to  less  than  9  parts  of  phosphorus,  or  only  one 
seventh  of  62. 

Even  though  the  nitric  acid  maybe  at  once  neutralized  by  reac- 
tion with  calcium  carbonate,  it  is  known  that  the  liberated  carbonic 
acid  exerts  an  influence  in  the  conversion  of  insoluble  phosphates 
and  potassium  salts  into  soluble  compounds. 

Of  course,  the  quantity  of  organic  acids  and  carbonic  acid  other- 
wise produced  in  the  decay  of  organic  matter  is  many  times  as 
great  as  that  of  nitric  acid.  (See  also  page  633.) 

Recent  investigations  of  Hall,  Miller,  and  Gimingham  (Pro- 
ceedings Royal  Society,  1908)  seem  to  prove  that  nitrification 
proper  does  not  occur  in  acid  soils,  and  that  crops  growing  on 
such  soils  must  take  up  their  supplies  of  nitrogen  in  the  form 
of  ammonium  salts,  formed  in  the  process  of  ammonificatioh. 
It  is  shown,  however,  that  there  may  be  a  small  amount  of  nitri- 
fication in  soils  that  are,  on  the  whole,  acid,  but  which  contain 
here  and  there  particles  of  calcium  carbonate  within  whose  limited 
sphere  of  influence  the  soil  is  alkaline  and  nitrification  takes  place. 

Under  certain  abnormal  conditions,  as  under  a  slime  or  scum 
from  sewage  which  prevents  access  of  air,  some  denitrification 
may  occur.  In  this  process  the  denitrifying  bacteria  may  even 
decompose  nitrates  in  order  to  secure  oxygen,  and  the  element 
nitrogen  may  be  liberated  as  free  gas.  Such  loss  may  readily  occur 
in  the  decay  of  manure  in  piles,  but  in  normal  soils  there  is  prac- 
tically no  denitrification. 

METHODS  OF  SUPPLYING  ORGANIC  MATTER 

There  are  three  general  methods  of  supplying  organic  matter 
to  the  soil  in  practical  agriculture: 


ORGANIC  MATTER  AND  NITROGEN 


199 


(1)  By  green  manures  and  crop  residues. 

(2)  By  accumulations  in  pasturing. 

(3)  By  applications  of  farm  manure. 

So  much  has  been  said  and  written  regarding  the  value  of  farm 
manure  that  it  is  common  talk  that  the  manurial  value  of  the  food 
is  almost  wholly  recovered  in  the  manure;  and  there  is  even  a  vague 
notion  in  the  minds  of  some  that  the  manure  is  worth  more  for 
soil  improvement  than  is  the  food  from  which  the  manure  is  made; 
while  it  is  very  generally  believed  that  pasturing  land  increases  the 
fertility  of  the  soil. 

The  fact  is  that  the  most  important  and  least  appreciated  method 
of  maintaining  or  increasing  the  supply  of  organic  matter  in  the 
soil  is  by  the  use  of  green  manures  and  crop  residues.  This  is  best 
understood  by  considering  the  digestibility  of  common  food  stuffs 
and  by  applying  mathematics  to  the  data  (see  Table  29). 

TABLE  29.  AVERAGE  DIGESTIBILITY  OF  SOME  COMMON  FOOD  STUFFS 


FOOD  STUFFS 

PER  CENT  DIGESTED 
OF  TOTAL  IN  FOOD 

DRY  MATTER  OF  FOOD 
RECOVERED  IN  MANURE 

Dry  Matter 

Nitrogen 

Per  Cent 

Pounds 
per  Ton 

Pasture  grasses      

71 

66 
67 

61 
61 

60 

48 

43 
60 

63 
79 
64 

70 

Qi 
61 

70 
67 

81 

57 
62 

74 

3° 
ii 

45 

42 

52 
49 

78 
76 

79 

29 

34 

33 

39 
39 
40 

52 

57 
40 

37 

21 
36 

3° 
9 
39 

58o 
680 
660 

780 
780 
800 

IO4O 
II4O 
800 

740 
42O 
720 

6oO 

180 

780 

Red  clover,  green  

Alfalfa,  green    

Mixed  meadow  hay    

Red  clover  hay      

Alfalfa  hay   

Oat  straw     

Wheat  straw      

Corn  stover  

Shock  corn   

Corn-and-cob  meal     

Corn  ensilage    

Oats    

Corn    .... 

Wheat  bran  

200       SYSTEMS   OF   PERMANENT   AGRICULTURE 

Thus,  when  pasture  grasses  containing  one  ton  of  dry  matter 
are  eaten,  only  580  pounds  of  the  dry  matter  consumed  will  be  re- 
turned to  the  land  in  the  droppings;  and  the  manure  made  from 
one  ton  of  dry  clover  hay  contains  only  780  pounds  of  dry  matter 
instead  of  the  2000  pounds  taken  from  the  field.  In  other  words, 
a  ton  of  clover  plowed  under  will  add  nearly  three  times  as  much 
organic  matter  to  the  soil  as  can  possibly  be  recovered  in  the  ma- 
nure if  the  clover  is  fed.  In  the  case  of  oat  straw,  about  one  half 
is  digested  and  one  half  recovered  in  the  manure,  while  only  one 
tenth  of  the  dry  matter  of  corn  is  found  in  the  manure. 

It  must  be  kept  in  mind,  furthermore,  that  to  return  even  these 
proportions  of  organic  matter  to  the  land  requires  that  the  manure 
shall  be  applied  to  the  soil  before  losses  occur  by  fermentation  and 
decay. 

The  Maryland  Experiment  Station  allowed  80  tons  of  manure 
to  lie  in  an  uncovered  pile  exposed  to  the  weather  for  one  year, 
during  which  time  the  amount  was  reduced  to  27  tons. 

Professor  Shutt,  Chief  Chemist  for  the  Experiment  Stations  of 
the  Dominion  of  Canada,  exposed  two  tons  of  manure  containing 
1938  pounds  of  organic  matter,  from  April  29  to  August  29,  four 
months,  during  which  time  the  organic  matter  was  reduced  by 
fermentation  and  decay  to  655  pounds.  During  the  same  time  the 
nitrogen  was  reduced  from  48.1  pounds  to  27.7  pounds. 

In  ordinary  farm  practice  more  or  less  loss  of  organic  matter  is 
almost  certain  to  occur  unless  the  manure  is  applied  to  the  soil 
within  a  day  or  two  after  it  is  produced. 

Because  the  nitrogen  of  the  soil  is  contained  in  the  organic  matter 
and  must  be  applied  in  that  form  in  general  farming,  and  because 
the  figures  are  available,  the  per  cent  of  nitrogen  digested  is  shown 
in  Table  29  for  the  common  food  stuffs  named.  The  fact  that  62 
per  cent  of  the  nitrogen  in  red  clover  hay  is  digested  means  that 
only  38  per  cent  of  the  nitrogen  in  the  food  consumed  will  be 
recovered  in  the  solid  excrement.  If  the  food  ration  consists  of 
equal  parts  of  corn  and  clover  hay,  the  solid  excrement  will  contain 
31  per  cent,  or  less  than  one  third,  of  the  nitrogen  in  the  food. 
Of  the  remaining  69  per  cent,  about  one  third  will  be  retained  by 
the  animal  (or  secreted  in  milk)  and  two  thirds  excreted  in  the 
liquid  manure,  as  a  general  average  in  live-stock  farming  for  animal 


ORGANIC   MATTER  AND   NITROGEN 


2OI 


products.  Mature  work  animals  excrete  practically  as  much 
nitrogen  as  they  consume.  These  facts  certainly  emphasize  the 
importance  of  saving  all  liquid  manure  and  the  danger  of  loss 
of  nitrogen  in  that  form. 

In  a  series  of  digestion  experiments  (not  yet  published)  con- 
ducted by  the  Illinois  Experiment  Station,  with  six  milk  cows,  dur- 
ing a  period  of  1 5  days,  the  average  daily  consumption  of  food  per 
cow  was  19.67  pounds  of  dry  matter  contained  in  a  ration  of  clover 
hay,  corn  silage,  and  mixed  concentrates,  including  corn,  oats, 
wheat  bran,  gluten  meal,  and  linseed  meal.  The  total  dry  matter 
recovered  in  the  dung  and  urine  amounted  to  8.1 1  pounds,  or  41.23 
per  cent.  (With  heavy  feeding  the  digestibility  is  appreciably 
less  than  with  lighter  feeding.) 

Of  the  nitrogen  consumed,  80.32  per  cent  was  recovered  in  the 
dung  and  urine,  and  20.12  per  cent  in  the  milk,  indicating  a  slight 
loss  from  the  animal  bodies. 

Of  the  phosphorus  consumed,  73.34  per  cent  was  recovered  in  the 
manures  and  22.28  per  cent  in  the  milk,  only  4.38  per  cent  being 
retained  by  the  animals. 

Of  the  potassium  taken  in  the  food,  76.02  per  cent  was  recovered 
in  the  manures  and  13.69  per  cent  in  the  milk,  the  balance,  10.29 
per  cent,  probably  having  been  largely  excreted  through  the  skin. 
The  experiments  were  conducted  the  last  half  of  June.  (Consider- 
able amounts  of  commercial  potassium  salts  were  once  regularly 
obtained  from  the  washing  of  sheep  wool.)  Table  30  shows  these 
results  in  more  detail  for  ready  comparison: 

TABLE  30.   PLANT  FOOD  RECOVERED  FROM  FOOD  CONSUMED  BY  MILK  Cows 
Illinois  Experiments:    Average  of  90  Days 


PLANT-FOOD  ELEMENTS 

RECOVERED 
IN  MILK 

RECOVERED 
IN  DUNG 

RECOVERED 
IN  URINE 

NOT  RE- 
COVERED IN 
TOTAL  MA- 
NURES 

Nitrogen,  per  cent      

20.12 
22.28 
13.69 

35-56 

72.33 
16.70 

44.76 
I.OI 
59-32 

19.68 
26.66 
23.98 

Phosphorus,  per  cent      

Potassium,  per  cent    

As  an  average  of  the  best  three  cows,  the  plant  food  not  recovered 
in  the  total  solid  and  liquid  manures  was  25.03  per  cent  of  the 


202       SYSTEMS    OF   PERMANENT   AGRICULTURE 


nitrogen,  28.07  per  cent  of  the  phosphorus,  and  28.45  Per  cen^  of 
the  potassium,  of  the  food  consumed,  the  differences  being  prac- 
tically accounted  for  by  the  larger  amounts  of  milk  produced  by  the 
best  cows.  However,  the  poorest  cow  of  the  six,  in  milk  produc- 
tion, digested,  during  the  three  successive  5-day  periods,  47.18 
per  cent,  44.77  per  cent,  and  52.54  per  cent,  respectively,  of  the 
total  phosphorus  consumed  in  the  food;  or,  as  an  average  of  the 
15-day  period,  only  52.94  per  cent  of  the  phosphorus  taken  in  the 
food  was  recovered  in  the  dung  and  urine  from  this  cow. 

The  Pennsylvania  Experiment  Station  (Annual  Report  for  1899- 
1900,  page  321)  reports  digestion  experiments  with  two  milk  cows 
during  a  period  of  50  days,  with  the  results  shown  in  Table  31. 
The  rations  fed  were  three  fifths  mixed  clover  and  timothy  hay, 
and  two  fifths  concentrates,  including  corn  meal,  buckwheat 
middlings,  cotton-seed  meal,  and  linseed  meal. 

TABLE  31.   PLANT  FOOD  RECOVERED  FROM  FOOD  CONSUMED  BY 

MILK  Cows 
Per  Cow  for  50  Days:  Average  for  2  Cows:  Pennsylvania  Experiments 


NOT     RECOV- 

PLANT-FOOD ELEMENTS 

CONSUMED 
IN  50  DAYS 

RECOVERED 
IN  MILK 

RECOVERED 
IN  DUNG 

RECOVERED 
IN  URINE 

ERED   IN 

TOTAL 

MANURES 

Nitrogen,  pounds    .     . 

67.96 

IJ-39 

21.46 

36.07 

10.43 

Phosphorus,  pounds    . 

9-73 

2.06 

6-75 

•13 

2.85 

Potassium,  pounds 

37-68 

3-76 

5-93 

28.38 

3-37 

Nitrogen,  per  cent  .     . 

TOO 

16.76 

31-58 

53-06 

I5-36 

Phosphorus,  per  cent  . 

100 

21.17 

69-37 

i-34 

29.29 

Potassium,  per  cent     . 

100 

9.98 

15-74 

75-32 

8.94 

In  the  Pennsylvania  experiments  both  the  nitrogen  and  potas- 
sium are  slightly  more  than  accounted  for,  but  8.12  per  cent  of  the 
phosphorus  in  the  food  consumed  was  retained  by  the  animals, 
probably  in  part  for  the  formation  of  bones  in  unborn  calves. 

As  an  average  of  both  the  Pennsylvania  and  Illinois  experiments, 
only  one  third  (exactly  33.57  per  cent)  of  the  nitrogen  consumed 
was  recovered  in  the  dung,  and  nearly  one  half  (48.91  per  cent)  was 
excreted  in  the  urine.  These  facts  are  worth  remembering,  and 
also  that  28  per  cent  of  the  phosphorus  consumed  was  not  recov- 
ered in  the  total  manurial  excrements. 


ORGANIC   MATTER  AND   NITROGEN 


203 


Pennsylvania  Bulletin  63  reports  an  experiment  covering  two 
months,  with  four  steers,  two  fed  on  a  cement  floor  with  the  manure 
kept  tramped  under  their  feet,  and  two  on  an  earth  floor  from  which 
the  manure  was  piled  into  an  adjoining  stall  and  kept  under 
cover.  If  we  assume  no  loss  from  the  litter  used,  the  following 
percentages  were  recovered  from  the  food  consumed: 

PERCENTAGES  RECOVERED  OF  PLANT  FOOD  IN  FEED 


METHOD  OF  KEEPING  MANURE 

NITROGEN 

PHOSPHORUS 

POTASSIUM 

On  cement  floor,  tramped  .  . 
On  earth  floor,  piled  .  .  . 

Average  per  cent  recovered 

84.8 

54-o 

8l-3 
69.0 

91-5 
71.0 

69.40 

75-15 

81.25 

Of  the  total  dry  matter  used  for  feed  and  bedding,  40.35  and 
31.03,  or,  as  an  average,  35.69  per  cent  was  recovered  in  the  manure. 

In  Table  32  are  given  data  (in  part  estimated)  from  an  experi- 
ment by  the  Ohio  Station  (Bulletin  183)  in  which  28  steers  were 
fed  on  a  cement  floor  from  December  i,  1904,  to  June  i,  1905,  a 
period  of  six  months,  or  182  days,  during  which  time  the  average 
weight  of  the  steers  increased  from  872  to  1230  pounds. 

At  best,  these  results  can  be  considered  only  as  approximations, 
except  as  to  the  composition  of  the  manure  and  the  phosphorus 
added  in  the  raw  rock,  but  they  are  of  interest  and  of  some  value  as 
indicating  what  can  be  accomplished  under  the  conditions. 

The  amounts  of  feed  and  bedding  used  were  accurately  weighed, 
but  their  plant-food  content  was  computed  from  accepted  averages 
from  each  material.  "The  steers  were  turned  out  of  the  stable 
once  a  day  to  get  water,  and  were  allowed  to  run  in  the  yards  from 
one  to  two  or  three  hours,  consequently  some  manure  was  left  in 
the  yards."  One  would  assume  from  this  that  one  tenth  or  more  of 
the  excrements  were  voided  in  the  yards. 

An  experiment  with  100  sheep  (averaging  84  pounds  each)  for  a 
feeding  period  of  112  days  was  conducted  by  the  Ohio  Station,  in 
which  more  definite  data  were  secured.  Of  the  feed,  26,936  pounds 
consisted  of  hays  which  were  analyzed;  while  accepted  averages 
were  used  only  for  the  standard  concentrates,  including  20,057 
pounds  of  corn,  905  pounds  of  cotton-seed  meal;  and  905  pounds 


204       SYSTEMS   OF   PERMANENT   AGRICULTURE 


TABLE  32.   RECORD  OF  Six  MONTHS'  FEEDING  OF  28  STEERS  ON 

CEMENT  FLOOR 
Ohio  Experiment  Station 


MATERIALS 

TOTAL 
AMOUNT 
(Pounds) 

DRY 
MATTER 
(Pounds) 

NITROGEN 
(Pounds) 

PHOSPHORUS 
(Pounds) 

POTASSIUM 
(Pounds) 

Wheat  bran   .... 
Corn  meal      .... 
Linseed  meal      .     .     . 
Cotton-seed  meal     .     . 
Corn  silage    .... 
Corn  stover   .... 
Mixed  hay     .... 
Total  feed      .... 

9448 
48128 
5593 
5097 
63231 
4896 
31814 

8324 
40909 
5083 
4685 
15808 
4406 
26946 

252-3 
875-9 
304.0 
346.1 
177.0 

5°-9 
448.6 

1  2O.  I 
148.2 
40.9 
64.6 
30.6 
6.2 
37-8 

126.2 
159.8 

63-7 
36.8 
194.2 
56.8 
409-3 

106161 

2454.8 

448.4 

1046.8 

Straw  bedding    .     .     . 
Raw  rock  phosphate    . 

39033 

4753 

35I31 

4753 

230-3 

2O.6 

564.6 

165.2 

Total  supplied     

146045 

2685.1 

1033-6 

1212 

Total  manure  ....     255203 

49698 

2006.0 

799-0 

1064 

PERCENTAGES  RECOVERED 


From  total  supplied   

•2A.O 

74.7 

77.  "? 

87.8 

With  phosphate  excluded    .     .     . 

31.8 

74-7 

50.0 

87.8 

Corrected  for  loss  in  yards       .     . 

35-3 

83.0 

55-6 

97.6 

of  linseed  meal;  and  for  3020  pounds  of  oat  straw  used  for 
bedding.  It  is  understood  that  the  sheep  were  kept  confined  in 
the  stables  during  the  entire  time. 

Eight  different  analyses  were  made  of  the  manure,  and  the  Ohio 
Station  computes  that,  of  the  total  plant  food  contained  in  the  feed 
and  bedding,  64  per  cent  of  the  nitrogen,  79  per  cent  of  the  phos- 
phorus, and  97  per  cent  of  the  potassium,  were  recovered  in  the 
manure. 

Wood,  of  the  University  of  Cambridge,  England,  reports  an 
experiment  with  four  heifers  to  determine  losses  in  making  and 
storing  farm  manure  (Journal  of  Agricultural  Science,  April,  1907). 

The  experimental  feeding  began  on  January  31,  1906,  and  ended 
on  April  25,  1906,  a  period  of  84  days.  During  this  time  two  of  the 
animals  consumed  13,720  pounds  of  mangels  (containing  1784 


ORGANIC   MATTER   AND   NITROGEN 


205 


pounds  of  dry  matter),  1176  pounds  of  hay,  and  used  up  1963 
pounds  of  straw  as  food  and  litter.  The  other  two  animals  in  an 
adjoining  stall  consumed  exactly  the  same  amounts  of  mangels 
and  hay,  100  pounds  less  straw,  and,  in  addition,  672  pounds  of 
oil  cake  made  from  hulled  cotton  seed. 

The  stalls  in  Which  the  animals  were  housed  during  the  experi- 
ment were  bricked  up  to  the  highest  level  reached  by  the  accumu- 
lated manure.  The  floors  were  not  cemented,  but  were  made  of 
clay  which  was  well  rammed,  and  through  which,  according  to 
Wood's  statement,  "  there  could  be  little  leakage  of  soluble  con- 
stituents." 

The  manure  was  kept  tramped  under  the  feet  of  the  animals, 
sampled  for  analysis  at  the  end  of  the  feeding  period  without 
disturbing  the  mass,  then  left  in  the  compact  condition  for  six 
months  (till  November  6,  1906),  when  it  was  sampled  and  weighed 
(8075  pounds  from  lot  i  and  8106  from  lot  2)  and  applied  to  the 
soil.  Following  are  the  essential  results: 

LOT  i.   (CAKE  NOT  FED) 


CONSTITUENTS 

DRY 

MATTER 

NITROGEN 

PHOS- 
PHORUS 

POTASSIUM 

In  total  feed  and  bedding,  pounds  .     . 

4421.0 

47-9 

5-5 

93-  1 

Percentage  found  '  in  fresh  manure     . 

58.6 

75-2 

67-5 

86.4 

Percentage  applied  to  the  soil     .     .     . 

42.4 

64.6 

67-5 

72.8 

LOT  2.   (CAKE  FED) 


In  total  feed  and  bedding,  pounds  .     . 
Percentage  found  l  in  fresh  manure     . 
Percentage  applied  to  the  soil     .     .     . 

4942.0 
60.0 
41.6 

9°-3 

78.5 
51.6 

14.8 
69-3 
69-3 

105.0 

71.1 

1  Assuming  no  loss  of  phosphorus  during  storage. 

Wood  computes  that  the  following  percentages  from  the  oil 
cake  fed  were  recovered  and  applied  to  the  soil: 

Dry  matter  .     .     .     .  29  per  cent. 

Nitrogen       37  per  cent. 

Phosphorus  ....  70  per  cent. 

Potassium 52  per  cent. 


206       SYSTEMS   OF   PERMANENT   AGRICULTURE 


As  a  general  average  for  dairy  farming,  cattle  feeding,  and  sheep 
feeding,  it  is  shown  that  practically  one  third  of  the  organic  matter, 
three  fourths  of  the  nitrogen,  and  three  fourths  of  the  phosphorus 
contained  in  the  feed  and  bedding  are  recovered  in  the  total 
manures.  Nearly  all  of  the  potassium  may  be  recovered  except 
that  sold  in  milk.  (Some  potassium  may  be  excreted  through  the 
skin,  especially  in  hot  weather,  but  even  this  is  washed  off  in  the 
pastures  by  summer  rains.) 

Emmet  and  Grindley  have  reported  the  -following  suggestive 
data  from  digestion  experiments  with  swine  (Journal  American 
Chemical  Society  (1909),  31,  577): 

COEFFICIENTS  OF   DIGESTIBILITY   OF   THE  CONSTITUENTS  IN  THE   FEEDS 

CONSUMED 
Per  Cent  Digested 


FOOD  RATION 

ANIMAL 

DRY 

SUBSTANCE 

ORGANIC 
MATTER 

PROTEIN 
(Nitrogen) 

PHOS- 
PHORUS 

Ground  corn      

Pie  A 

87.1 

86.7 

80.6 

64  7 

Ground  corn      

PigB 

86.5 

86.2 

76.9 

65-4 

Ground  corn  and  middlings 
Ground  corn  and  middlings 

Pig  A 
PigB 

87.3 
86.8 

87.6 

87.2 

84.4 
82.4 

74.6 

77-7 

Average  of  four       .... 

86.9 

86.9 

8l.2 

70.6 

It  is  common  knowledge  among  farmers  that  swine  fed  largely 
on  grain  produce  but  little  solid  manure;  and  in  these  experiments 
only  about  13  per  cent  of  the  organic  matter,  20  per  cent  of  the 
nitrogen,  and  30  per  cent  of  the  phosphorus  were  recovered  in  the 
solid  excrement.  However,  the  existing  data  are  not  sufficient  to 
justify  the  adoption  of  these  determinations  as  representing  the 
average  digestibility  by  swine  of  the  phosphorus  contained  in  the 
grain  rations.  That  the  normal  coefficient  is  high,  is  evidenced  by 
the  fact  that,  unlike  most  animals,  swine  normally  excrete  very 
appreciable  amounts  of  phosphorus  in  the  urine. 

The  production,  composition,  care,  and  value  of  farm  manure  are 
discussed  in  a  later  chapter. 


ORGANIC   MATTER   AND   NITROGEN  207 

THE  FIXATION  OF  FREE  NITROGEN 

As  already  stated,  the  nitrogen  naturally  in  the  soil  is  contained 
essentially  in  the  organic  matter.  Any  process  which  tends  to 
decompose  or  destroy  this  organic  matter,  such  as  nitrification  or 
other  forms  of  oxidation,  will  also  tend  to  reduce  the  total  stock  of 
nitrogen  in  the  soil,  whether  removed  by  cropping  or  lost  by  leach- 
ing. Because  of  this  fact,  the  matter  of  restoring  nitrogen  to  the 
soil  becomes  of  very  great  importance.  Of  course,  a  part  of  the 
nitrogen  removed  in  crops  may  be  returned  in  the  manure  produced 
on  the  farm;  and  nitrogen  may  also  be  bought  in  the  markets  in 
such  forms  as  dried  blood  (14  per  cent),  sodium  nitrate  (15!-  per 
cent) ,  and  ammonium  sulf ate  (20  per  cent) ;  but  when  we  bear  in 
mind  that  such  commercial  nitrogen  costs  from  1.5  to  20  cents  a 
pound,  and  that  one  bushel  of  corn  contains  about  one  pound  of 
nitrogen,  it  will  be  seen  at  once  that  the  purchase  of  nitrogen 
cannot  be  considered  practicable  in  general  farming,  although  in 
market  gardening,  and  in  some  other  kinds  of  intensive  agriculture, 
commercial  nitrogen  can  often  be  used  with  very  marked  profit. 

Considering  all  of  these  facts,  and  the  additional  facts  that  there 
are  about  seventy-five  million  pounds  of  atmospheric  nitrogen 
resting  upon  every  acre  of  land,  and  that  it  is  possible  to  obtain 
unlimited  quantities  of  nitrogen  from  the  air  for  the  use  of  farm 
crops,  and  at  small  cost,  the  inevitable  conclusion  is,  that  the  inex- 
haustible supply  of  nitrogen  in  the  air  is  the  store  from  which  we 
must  draw  to  maintain  a  sufficient  amount  of  this  element  in  the 
soil  for  the  most  profitable  crop  yields. 

It  is  often  stated  that  legume  plants,  such  as  clover,  have  power 
to  obtain  free  nitrogen  from  the  air.  This  is  not  strictly  true. 
Red  clover,  for  example,  has  no  power  in  itself  to  get  nitrogen  from 
the  air.  ,It  is  true,  however,  that  certain  microscopic  organisms  * 
which  commonly  live  in  tubercles  upon  the  roots  of  the  clover  plant 
do  have  the  power  to  take  up  free  nitrogen  and  cause  it  to  unite 
with  other  elements  to  form  compounds  suitable  for  plant  food. 

1  Among  the  scientists  who  were  prominent  in  making  these  discoveries  regard- 
ing the  action  of  bacteria  in  the  fixation  of  free  nitrogen  were  Hellriegel,  Willfarth, 
and  Nobbe  in  Germany,  Atwater  in  America,  Lawes  and  Gilbert  in  England,  and. 
Boussingault  and  Ville  in  France. 


208       SYSTEMS   OF   PERMANENT   AGRICULTURE 

The  clover  plant  then  draws  upon  this  combined  nitrogen  in  the 
root  tubercles,  and  makes  use  of  it  in  its  own  growth,  both  in  the 
tops  and  in  the  roots  of  the  plant. 

These  nitrogen-fixing  bacteria  live  in  tubercles  upon  the  roots  of 
various  legume  plants,  such  as  red  clover,  white  clover,  alfalfa, 
sweet  clover,  cowpeas,  soy  beans,  vetch,  field  peas,  garden  peas, 
field  and  garden  beans,  etc.  The  tubercles  vary  in  size  from  smaller 
than  a  pinhead  to  larger  than  a  pea,  varying  somewhat  with  the 
different  kinds  of  plants,  being  especially  small  upon  some  of  the 
clovers,  and  large  upon  cowpeas  and  soy  beans.  The  tubercles  are, 
of  course,  easily  seen  with  the  eye,  but  the  tubercle  is  only  the  home 
of  the  bacteria,  somewhat  as  the  ball  upon  the  willow  twig  is  the 
home  of  the  insects  within.  The  bacteria  themselves  are  far  too 
small  to  be  seen  with  the  unaided  eye,  although  they  can  be  seen 
by  means  of  the  powerful  microscope.  Several  million  bacteria 
may  inhabit  a  single  tubercle.  It  is  not  necessary  to  see  the 
bacteria,  because  if  we  find  the  tubercles  upon  the  roots  of  the  plant, 
we  know  that  the  bacteria  are  present  within,  otherwise  the  tubercle 
would  not  be  formed.1 

It  has  also  been  demonstrated  that,  as  a  rule,  there  are  different 
modifications  of  nitrogen-fixing  bacteria  for  markedly  different 
species  of  legume  plants.  Thus,  we  have  one  kind  of  bacteria  for 
red  clover,  another  for  cowpeas,  another  for  soy  beans,  and  still  a 
different  kind  for  alfalfa. 

There  are  some  noteworthy  exceptions  to  this  rule.  Thus,  the 
bacteria  of  alfalfa  (Medicago  saliva)  and  of  common  sweet  clover 
(Mellilotus  alba)  are  interchangeable,  and  apparently  identical, 
as  are  also  the  bacteria  of  cowpeas  (Vigna  unguicidata)  and  the 
widely  distributed  native  partridge  pea  (Cassia  chamaecrista) , 
relationships  of  much  importance  in  connection  with  soil  inocula- 
tion for  alfalfa  and  cowpeas.  There  is  evidence  that,  by  a  compara- 
tively long  process  of  breeding,  or  evolution,  the  bacteria  which 
naturally  live  upon  one  kind  of  legume  may  gradually  develop  the 
power  to  live  upon  a  distinctly  different  legume  to  which  they  were 
not  at  first  adapted.  This  change  which  has  been  brought  about 

1  A  few  plants  form  starchy  nonbacterial  tubers,  which  may  be  of  large  size, 
like  the  potato  and  artichoke,  or  of  smaller  size,  as  on  the  rootstalks  of  nut  grass 
(Cy per  us  rotunda). 


ORGANIC   MATTER  AND   NITROGEN  209 

with  some  certainty  in  artificial  cultures,  and  which  very  possibly 
occurs  to  some  extent  in  farm  manure  from  legume  hay,  may  fur- 
nish bacteria  with  feeble  action  for  a  time,  but  ultimately,  no  doubt, 
with  full  power.  Of  course,  this  process  of  forcing  bacteria  to  live 
upon  a  legume  to  which  they  are  not  naturally  adapted  has  little 
or  no  practical  value,  because  it  is  unnecessary,  if  there  is  a  species 
of  bacteria  which  naturally  live  upon  the  same  legume.  On  the 
other  hand,  if,  by  any  such  process  of  breeding,  or  evolution,  a 
species  of  nitrogen-fixing  bacteria  could  be  developed  which  could 
live  on  a  nonleguminous  plant,  as  corn,  for  example,  it  would  be 
of  incalculable  value.  As  yet,  the  efforts  of  bacteriologists,  working 
on  this  problem,  have  given  only  negative  results,  so  far  as  known 
to  the  author. 

Attention  is  called  to  the  fact  that  there  are  numerous  instances 
where  two  different  kinds  of  plants  live  together  in  intimate  part- 
nership relation.  If  only  one  of  the  two  plants  receives  benefit 
from  this  relationship  or  association,  then  the  plant  receiving  the 
benefit  is  called  a  parasite.  Thus  the  mistletoe  is  a  parasite  upon 
the  elm  or  gum  or  other  tree  on  which  it  lives.  The  mistletoe 
draws  its  nourishment  from  the  tree.  The  tree  is  injured  rather 
than  benefited  by  the  mistletoe.  Dodder  is  also  a  parasitic  plant, 
living  upon  other  plants,  except  during  the  early  part  of  its  growth. 
Ticks  and  lice  are  common  examples  of  animal  parasites,  living 
upon  other  animals. 

In  some  cases  a  relationship  exists  which  is  not  parasitic,  but 
symbiotic.  The  term  symbiosis,  which  is  commonly  used  by 
biologists  to  define  this  relationship,  means  living  together  in 
mutual  helpfulness.  The  association  of  bees  and  flowers  may 
serve  to  illustrate  this  mutual  helpfulness,  although  this  is  not  an 
example  of  intimate  symbiosis.  Thus,  the  bees  obtain  their  food 
from  the  flowers  and,  in  turn,  the  flowers,  many  of  them,  are  in- 
capable of  producing  seed  or  fruit  unless  the  pollen  is  carried  from 
the  male  flower  to  the  female  flower  by  bees  or  other  agencies.  It 
is  well  known  that  plant  lice  and  ants  are  mutually  helpful. 

Likewise,  the  association  of  nitrogen-fixing  bacteria  and  legume 
plants  is  a  relationship  of  mutual  helpfulness,  and  this  is  one  of 
the  best  illustrations  of  what  is  meant  by  symbiosis.  The  legume 
furnishes  a  home  for  the  bacteria  and  also  furnishes  in  its  juice  or 


210       SYSTEMS   OF   PERMANENT   AGRICULTURE 

sap  most  of  the  nourishment  upon  which  the  bacteria  live.  The 
bacteria,  on  the  other  hand,  take  nitrogen  from  the  air,  contained 
in  the  pores  of  the  soil,  and  cause  this  nitrogen  to  combine  with 
other  elements  in  suitable  form  for  plant  food,  which  is  afterward 
given  up  to  the  legume  for  its  own  nourishment. 

Another  illustration  of  remarkable  parasitism,  if  not,  indeed, 
one  of  true  symbiosis,  is  found  in  the  common  lichens  living  upon 
rocks  and  trees.  The  lichen  is  not  a  single  plant,  but  two  plants,  — 
one  an  alga,  which  lives  upon  the  wood  or  stone,  and  the  other  a 
fungus,  which  lives  upon  the  alga.  Algae  also  live  in  the  free  state 
separate  from  fungi,  and  the  present  opinion  of  botanists  seems  to 
be  that  when  the  two  are  associated  in  the  form  of  lichens,  this 
association  is  not  detrimental,  but  rather  beneficial,  to  the  alga, 
as  well  as  to  the  parasitic  fungus.  If  this  is  true,  then  it  is  another 
case  of  true  symbiosis.  (It  is  now  known  that  some  fungi  have 
power  to  feed  upon  atmospheric  nitrogen,  and  probably  those 
in  lichens  furnish  combined  nitrogen  to  the  algae  upon  which  they 
live.) 

In  the  symbiosis  of  legume  plants  and  nitrogen-fixing  bacteria 
we  have  a  partnership  or  relationship  of  immeasurable  value  to 
agriculture.  Here  is  a  class  of  plants  (legumes)  that  are  capable 
of  consuming  or  utilizing  nitrogen  in  quantities  larger  than  could 
possibly  be  obtained  from  ordinary  soils  for  any  considerable 
length  of  time.  They  have  no  power  in  themselves  of  taking 
nitrogen  from  the  atmosphere,  and  to  them  the  symbiotic  relation 
with  this  low  order  of  plants  (the  nitrogen-fixing  bacteria,  Pseu- 
domonas  radicicola),  is  especially  helpful,  and  for  the  best  results 
it  is  absolutely  necessary. 

INOCULATION  FOR  NITROGEN  FIXATION 

While  it  is  true  that  nitrogen-fixing  bacteria  are  essential  to  the 
most  'successful  growing  of  legumes,  it  is  also  true  that,  as  a  very 
general  rule,  the  proper  bacteria  for  the  ordinary  legumes  are 
already  present  in  the  most  common  soil,  especially  where  the 
particular  legume  has  been  grown  in  the  vicinity  for  several  years, 
or  where  manure  made  from  the  legume  has  been  applied.  This 
applies  especially  to  alfalfa  in  the  alfalfa  country  of  the  West,  to 


ORGANIC   MATTER   AND   NITROGEN  211 

cowpeas  in  the  cowpea  country  of  the  South,  and  to  the  clovers 
throughout  the  Central  and  Eastern  states.  Where  the  special 
legume  has  not  been  grown  successfully  in  the  vicinity;  or  even  on 
fields  where  the  legume  has  not  been  grown  for  many  years,  and 
where  neither  manuring,  overflow,  nor  dust  storms  have  brought 
the  bacteria  from  other  fields,  it  is  worth  while  to  consider  inocula- 
tion. 

The  bacteria  for  clover,  cowpea,  and  vetch  are  now  very  widely 
distributed  over  the  United  States  (in  part  because  of  the  par- 
tridge pea  and  wild  vetches);  but  for  alfalfa  (except  in  alfalfa 
regions)  and  for  soy  beans,  the  question  of  inoculation  should 
always  be  considered.  For  inoculating  alfalfa,  either  alfalfa  soil  or 
sweet-clover  soil  can  be  used,  care  being  taken  to  use  only  well- 
infected  soil,  collected  where  the  plants  have  been  growing  for 
several  years,  well  provided  with  root  tubercles. 

The  accumulated  practical  experience  of  the  past  twenty  years, 
and  the  data  thus  far  reported  from  many  comparative  experi- 
ments, combine  to  prove  that  the  simplest  and  surest  and  most 
economical  method  of  inoculation  is  by  means  of  well-infected 
natural  soil,  collected  where  the  plants  are  thrifty  and  free  from 
noxious  weed  seeds,  although  the  danger  of  carrying  weed  seeds  or 
plant  diseases  by  overflow,  by  wind  storms,  and  in  purchased  ma- 
nures and  farm  seeds  is  probably  a  hundred  times  greater  than  by 
using  infected  soil  for  inoculation.  The  amount  of  soil  used  varies 
from  100  pounds  to  a  wagon  load  to  the  acre.  It  may  be  applied 
broadcast  with  some  degree  of  uniformity,  and  it  should  be  mixed 
with  the  surface  soil  without  delay,  as  by  harrowing  or  disking, 
because  exposure  to  the  sunlight  tends  to  destroy  the  bacteria. 

Successful  seed  inoculation  can  be  performed  with  fresh,  properly 
prepared  artificial  cultures,  but,  as  a  rule,  this  method  has  proved 
unsatisfactory.  Some  years  ago  German  promoters  undertook  to 
establish  the  business  of  selling  nitrogen  bacteria  for  seed  inocu- 
lation, and  more  recently  American  promoters  have  widely  ad- 
vertised similar  products,  but  failure  is  the  most  common  report 
from  their  use. 

For  large  seeds,  such  as  soy  beans,  a  very  satisfactory  method 
of  inoculation,  suggested  by  the  Illinois  Experiment  Station,  is  to 
thoroughly  moisten  the  seed  with  a  10  per  cent  solution  of  glue, 


212        SYSTEMS   OF   PERMANENT   AGRICULTURE 

immediately  sift  over  them  sufficient  dry,  pulverized,  infected  soil 
to  absorb  all  of  the  moisture,  thus  furnishing  a  coating  of  infected 
soil  for  every  seed.  The  seed  should  be  shoveled  over  a  few  times, 
then  screened,  and  planted  within  a  day,,  or  spread  out  to  dry, 
after  which  they  may  be  kept  as  long  as  though  not  covered  with 
dust.  The  coat  of  thoroughly  infected  soil  provides  a  much  better 
inoculation  than  is  common  from  the  use  of  artificial  cultures, 
and  it  does  not  interfere  with  drilling  the  seed  immediately  after 
treatment.  If  this  method  is  used  for  inoculating  small  seeds,  such 
as  alfalfa,  greater  care  must  be  taken  to  screen  them  afterward  to 
prevent  clusters  of  seeds  from  remaining  glued  together. 

If  seeds  are  moistened,  they  should  either  be  planted  very  soon 
thereafter  or  spread  out  and  thoroughly  dried,  otherwise  they  are 
likely  to  mold  and  lose  vitality.  Infected  soil  should  never  be  long 
exposed  to  bright  sunshine,  which  is  very  destructive  to  all  forms 
of  bacteria. 

There  has  been  much  discussion  during  recent  years  concerning 
the  development  of  unusually  virile  bacteria,  but  even  if  it  were 
possible  to  develop  and  maintain  in  the  soil  bacteria  of  greater 
nitrogen-fixing  power,  it  is  a  question  whether  the  discovery  would 
have  great  practical  value  (especially  after  the  first  year) ,  for  the 
simple  reason  that  bacteria  multiply  with  such  tremendous  rapid- 
ity that  we  may  soon  have  many  times  the  number  of  bacteria  that 
are  really  needed  to  do  the  work.  In  other  words,  the  increase  "in 
numbers  may  result  in  just  as  great  efficiency  as  would  result  from 
any  increased  power  of  the  individual  bacteria.  One  who  carefully 
studies  the  formation  of  root  tubercles  on  plants  growing  on  soils 
in  varying  conditions  or  degrees  of  infection  will  observe  that  on 
plants  sparsely  infected  the  individual  tubercles  or  clusters  develop 
to  enormous  size,  comparatively  speaking;  while  in  well-infected 
soils  the  individual  tubercles  are  much  smaller,  and  clusters  scarcely 
form.  It  is  also  observed  that  the  marked  effect  on  the  growth, 
color,  and  composition  of  the  plant  is  produced  even  though  only 
a  half-dozen  large  tubercles  form  on  the  roots.  It  is  very  evident 
that  the  relationship  between  the  bacteria  and  the  host  plant  is 
such  that  if  the  soil  is  sparsely  infected,  so  that  the  roots  come  in 
contact  with  but  few  bacteria,  and  but  few  tubercles  are  started, 
those  few  tubercles  will  be  so  enlarged,  either  in  individuals  or  as 


ORGANIC   MATTER   AND   NITROGEN  213 

clusters,  that  the  multiplication  and  activity  of  the  bacteria  are 
sufficient  to  meet  the  needs  of  the  host  plant  so  far  as  nitrogen  is 
concerned.  Of  course,  as  soon  as  the  soil  becomes  well  infected,  the 
plant  roots  come  in  contact  with  large  numbers  of  bacteria,  and 
many  tubercles  are  formed,  but  most  of  them  remain  smallj  and 
no  large  clusters  are  formed,  because  the  bacteria  in  the  large  num- 
ber of  small  tubercles  are  apparently  capable  of  furnishing  all  the 
nitrogen  needed  by  the  host  plant.  If  the  other  elements  were 
provided  in  greater  abundance,  the  tubercles  would  undoubtedly 
become  enlarged,  as  much  as  necessary  to  supply  the  nitrogen 
needed  to  balance  the  supply  of  the  other  plant-food  elements  util- 
ized by  the  plant. 

NITROGEN  FROM  SOIL  AND  AIR 

Experiments  or  demonstrations  almost  without  number  have 
been  performed  to  determine  the  amounts  of  nitrogen  taken  from 
the  air  by  various  legume  plants  when  grown  in  sand  cultures 
essentially  free  of  combined  nitrogen,  but  there  are  much  less  data 
concerning  the  relative  amounts  of  nitrogen  taken  from  the  soil 
and  from  the  air  by  legume  crops  grown  on  normal  cultivated  land. 

There  are  two  methods  by  which  such  information  can  be  se- 
cured with  a  fair  degree  of  satisfaction.  One  of  these  is  to  deter- 
mine the  amounts  of  nitrogen  in  infected  plants  and  in  similar 
plants  not  infected,  grown  on  the  same  type  of  soil;  and  the  other 
is  to  compare  the  total  nitrogen  content  of  a  nonleguminous  crop 
with  that  of  a  crop  of  infected  legume  plants,  grown  at  the  same 
time  on  similar  soil.  Though  not  strictly  exact,  these  methods 
furnish  practically  correct  information. 

In  Table  33  are  shown  the  results  of  a  field  experiment  to  de- 
termine the  amount  of  nitrogen  taken  from  the  air  by  alfalfa  when 
grown  on  the  common  corn-belt  prairie  land  (Illinois  Bulletin 
76). 

The  difference  between  the  amount  of  nitrogen  contained  in  the 
crop  from  the  inoculated  soil,  on  the  one  hand,  and  in  the  crop  from 
the  uninoculated  soil,  on  the  other  hand,  represents  the  amount  of 
nitrogen  secured  by  the  bacteria.  In  no  case  will  this  give  too  much 
credit  to  the  bacteria;  but,  if  any  unavoidable  cross  inoculation 


214 


TABLE  33.   FIXATION  OF  NITROGEN  BY  ALFALFA  IN  FIELD  CULTURE 
Illinois  Experiments  on  Common  Prairie  Land 


PLOT 
No. 

TREATMENT  APPLIED 

DRY 

MATTER 
IN  CROPS 
(Pounds) 

NITROGEN 
IN  DRY 
MATTER 
(Per  Cent) 

NITROGEN 
IN  CROPS 
(Pounds) 

NITROGEN 

FIXED    BY 

BACTERIA 
(Pounds) 

ia 
ib 

20, 
2b 

3« 

3& 

None 

1180 

2300 

1300 
2570 

1740 
3290 

I.8S 
2.70 

2.O2 

2.65 

2.03 
2.71 

2I.8l 
62.04 

26.20 

68.02 

35-4° 
89.05 

Bacteria  

40.23 

Lime  . 

Lime,  bacteria  

41.82 

Lime,  phosphorus      .... 
Lime,  phosphorus,  bacteria 

53-65 

occurred  during  the  progress  of  the  experiment,  these  amounts 
might  understate  the  effect  of  the  bacteria.  It  is  very  probable, 
however,  that  the  increased  root  development,  induced  by  remov- 
ing the  nitrogen  limit  in  plant  growth,  would  make  it  possible  for 
the  infected  plants  to  secure  somewhat  more  soil  nitrogen  than 
otherwise.  (Note  the  effect  of  phosphorus  in  the  record.)  How- 
ever, this,  too,  should  perhaps  be  placed  to  the  credit  of  the  bac- 
teria, even  though  it  is  not  atmospheric  nitrogen,  because  if  such 
nitrogen  existed  in  the  soil  solution,  it  would  soon  have  been  lost 
in  drainage  waters  if  not  taken  up  by  the  enlarged  root  system  of 
the  growing  crop. 

Slightly  more  than  one  third  of  the  total  nitrogen  contained 
in  the  crop  from  the  inoculated  unfertilized  plot  was  secured  from 
the  soil,  with  larger  proportions  and  larger  actual  amounts  for  the 
other  plots. 

It  should  be  borne  in  mind  that  nitrogen  is  required  for  root 
growth  as  well  as  for  growth  above  ground,  and  that  three  other 
crops  of  alfalfa  were  cut  from  these  plots  during  the  season,  this 
cutting  having  been  made  on  May  28.  Evident  cross  inoculation 
occurred  before  a  second  cutting  was  obtained;  but  the  data  given 
in  Table  33  indicate  that  plot.ifr  secured  about  172  pounds  of 
nitrogen  from  the  air  during  the  season,  the  yield  of  air-dry  hay 
having  been  2563  pounds  for  the  first  cutting  and  10,980  for  the 


ORGANIC   MATTER  AND    NITROGEN  215 

season.  The  value  of  this  "  gathered  "  nitrogen  amounts  to  $25.80 l 
per  acre  at  15  cents  a  pound.  Similarly,  plot  36,  yielding  3625 
pounds  of  air-dry  hay  in  the  first  cutting  and  17,060  per  acre  for 
the  season,  "gathered"  252  pounds  of  nitrogen  from  the  air, 
worth  $37.80  at  15  cents  a  pound. 

The  Illinois  Station  also  conducted  a  series  of  pot  cultures  in- 
cluding 12  inoculated  pots  and  12  similar  uninoculated  pots,  the 
results  of  which  support  very  well  the  field  experiments  reported 
in  Table  33.  (See  Illinois  Bulletin  76.) 

The  Dominion  of  Canada  Experiment  Stations  (Report  for  1905) 
as  an  average  of  twenty-one  pot  cultures  increased  the  nitrogen 
content  of  the  soil  from  .0392  per  cent  to  .0457  by  growing  mam- 
moth clover  for  two  successive  seasons,  and  turning  it  all  back  into 
the  soil.  This  amounted  to  179  pounds'  increase  of  nitrogen  per 
acre  to  a  depth  of  9  inches,  but  it  should  be  noted  that  the  soil  was 
extremely  poor  in  nitrogen,  containing  only  784  pounds  in  2  mil- 
lion at  the  beginning.  In  a  similar  plot  experiment  for  two  full 
seasons,  two  cuttings  of  mammoth  clover  and  all  residues  being 
returned  to  the  soil  each  season,  the  nitrogen  content  was  increased 
from  .0437  to  .0580  per  cent,  making  a  gain  of  175  pounds  per 
acre  to  a  depth  of  4  inches;  but  only  874  pounds  of  nitrogen  were 
contained  in  2  million  of  soil  at  the  beginning;  so  that  in  both  of 
these  experiments  the  results  are  not  very  different  than  would  be 
secured  in  sand  cultures.  The  clover  was  reseeded  each  year  and 
grown  without  a  nurse  crop.  The  average  annual  fixation  reported 
amounts  to  less  than  90  pounds  per  acre. 

In  another  experiment  by  the  Illinois  Station  (Bulletin  94) 
six  sets  of  immature  cowpea  plants  (10  plants  in  each  set)  were 
carefully  collected,  tops  and  roots.  Three  sets  were  infected,  the 
others  not  infected.  The  plants  were  taken  from  a  catch  crop 
grown  after  oats  had  been  harvested,  on  land  that  had  been  heavily 
cropped  with  corn  and  oats  until  nitrogen  had  become  a  limiting 
element,  especially  for  a  catch  crop  grown  after  oats.  As  a  general 
average,  the  infected  plants  contained  86  parts  of  nitrogen  in  the 
tops,  5  parts  in  the  roots,  and  9  parts  in  the  tubercles,  while  in 
direct  comparison  the  noninfected  plants  contained  25  parts  of 

1  "They  not  only  work  for  nothing  and  board  themselves,  but  they  pay  for  the 
privilege."  —  DAVENPORT. 


2i6       SYSTEMS   OF   PERMANENT  AGRICULTURE 


nitrogen  in  the  tops  and  2  parts  in  the  roots,  thus  indicating  that 
73  per  cent  of  the  nitrogen  contained  in  the  infected  plants  was 
secured  by  the  bacteria.  The  nitrogen  in  the  dry  matter  of  the 
infected  plants  varied  from  4.09  to  4.33  per  cent  in  the  tops, 
from  1.45  to  1.53  per  cent  in  the  roots,  and  from  5.76  to  6.05  per 
cent  in  the  tubercles;  while  the  nitrogen  in  the  dry  matter  of 
the  noninfected  plants  varied  from  2.32  to  2.69  per  cent  in  the 
tops,  and  amounted  to  .88  per  cent  (in  each  of  three  lots)  in  the 
roots.  From  an  experiment  with  soy  beans  by  the  Wisconsin 
Station  (Report  for  1907),  it  is  computed  that  only  14  per  cent  of 
the  nitrogen  contained  in  .well-infected  plants  was  secured  from  the 
air.  The  yield  of  dry  matter  was  practically  the  same,  but  the 
infected  plants  were  richer  in  nitrogen  and  protein,  and  thus  of 
better  quality.  "The  soy  beans  were  grown  on  low,  rich  soil  in 
these  experiments." 

The  Michigan  Station  (Bulletin  224)  reports  data  showing  that 
33  per  cent  of  the  nitrogen  in  soy  beans  was  secured  by  the  bacteria, 
on  well-infected  plants. 

As  an  average  of  20  untreated  plots  in  one  test,  and  of  16  plots 
treated  with  phosphorus  and  potassium  in  another  test,  both  over  a 
period  of  25  years,  in  a  four-year  rotation  of  corn,  oats,  wheat,  and 
hay  (mixed  clover  and  timothy),  the  Pennsylvania  Experiment 
Station  reports  the  following  yields  in  pounds  per  acre  per  annum : 

POUNDS  PER  ACRE 


TREATMENT 

CORN 

OATS 

WHEAT 

HAY 

Ears 

Stover 

Grain 

•Straw 

Grain 

Straw 

None   

2956 
3783 

IQSS 
2801 

J°33 
1279 

1403 
1762 

815 

1108 

1265 
1776 

2783 
4138 

Phosphorus,  potassium    . 

If  we  compute  the  nitrogen  in  the  three  uncultivated  crops  (see 
Table  23) ,  adopt  the  estimate  that  the  hay  was  three  fourths  clover 
and  one  fourth  timothy,  and  assume  the  soil  nitrogen  for  the  hay 
crops  to  be  as  indicated  by  a  curve  projected  from  the  amounts 
furnished  to  the  oats  and  wheat  crops,  then  the  clover  must  have 
secured  from  the  air  66  per  cent  of  its  nitrogen  when  grown  on 


ORGANIC   MATTER  AND   NITROGEN  217 

untreated  land,  and  64  per  cent  on  land  treated  with  phosphorus 
and  potassium,  the  average  annual  yields  of  nitrogen  per  acre 
being  29.1  pounds  for  oats,  25.9  for  wheat,  and  50.1  for  hay,  on 
untreated  land,  and  36.15  pounds  for  oats,  35.5  for  wheat,  and  75.5 
pounds  for  hay,  on  treated  land.  While  the  calculation  of  65  per 
cent  is  probably  near  the  truth  for  the  treated  land,  where  the 
nitrogen  is  likely  to  be  the  limiting  element  in  crop  production, 
the  marked  reduction  in  yield  of  nitrogen  between  the  oats  and  the 
wheat  crops  on  the  untreated  land  is  probably  not  a  true  index  of 
the  change  in  available  soil  nitrogen,  because  on  these  plots  phos- 
phorus is  certainly  the  limiting  element  for  wheat,  as  will  be  seen 
from  later  discussion. 

In  any  case,  we  are  safe  in  concluding  that  soil  which  will  fur- 
nish from  26  to  36  pounds  of  available  nitrogen  for  a  crop  of  oats 
or  wheat  will  also  furnish  approximately  as  much  for  the  hay  crops, 
whether  timothy  or  clover. 

Clover  and  other  legumes  take  available  nitrogen  from  the  soil 
in  preference  to  the  fixation  of  free  nitrogen  from  the  air,  the  latter 
being  drawn  upon  only  to  supplement  the  soil's  supply  and  thus 
balance  the  plant-food  ration.  In  other  words,  the  legumes  have  no 
nitrogen  limit  in  yielding  power  when  properly  infected,  but  with 
abundance  of  available  soil  nitrogen  constantly  provided  to  fully 
balance  other  essential  elements  or  factors,  there  is  little  or  no 
development  of  root  tubercles,  and  little  or  no  fixation  of  free  nitro- 
gen occurs. 

From  the  experimental  data  here  presented  or  referred  to,  and 
from  many  other  calculations  approximating  exactness,  the  con- 
clusion may  be  drawn  that  on  normally  productive  soils  at  least 
one  third  of  the  nitrogen  contained  in  legume  plants  is  taken  from 
the  soil,  not  more  than  two  thirds  being  secured  from  the  air. 
This  proportion  would  apply  to  the  nitrogen  content  of  the  roots 
as  well  as  to  the  tops;  so  that,  if  one  third  of  the  nitrogen  of  the 
entire  plant  is  in  the  roots  and  stubble,  and  two  thirds  in  the  crop 
harvested,  the  soil  would  neither  gain  nor  lose  in  nitrogen  because 
of  the  legume  crop  having  been  grown,  the  soil  having  furnished 
as  much  nitrogen  to  the  plant  as  remains  in  the  roots  and  stubble. 

When  grown  on  richer  soils,  such  legume  crops  leave  the  soil 
poorer  in  nitrogen;  but  on  poorer  soils,  furnishing  less  than  the 


218       SYSTEMS    OF   PERMANENT   AGRICULTURE 


normal  amount  of  available  nitrogen,  the  growing  of  such  legumes 
would  enrich  the  soil  in  proportion  to  its  poverty.  In  other  words, 
to  the  soil  that  hath  not,  shall  be  given;  but,  from  the  soil  that 
hath,  shall  be  taken  away. 

When  properly  infected,  legume  plants  have  power  to  make  nor- 
mal growth  and  full  development  on  soils  absolutely  devoid  of 
nitrogen,  if  available  mineral  plant  food,  limestone,  moisture, 
aeration,  and  all  other  essential  factors  are  provided  in  abundance 
or  perfection;  and  the  statement  sometimes  made  that  the  pres- 
ence of  soluble  nitrogen  is  necessary,  in  order  to  give  clover  a  start, 
is  not  correct,  as  witness  the  accompanying  illustrations  of  clover 
growing  in  purified  quartz  sand  void  of  nitrogen,  with  all  plant  food 


provided  except  nitrogen,  the  culture  on  the  right  marked  "  Bac- 
teria "  having  been  well  inoculated  with  the  clover  bacteria; 
while  the  middle  culture  was  started  in  exactly  the  same  manner, 
except  that  it  was  not  inoculated.  In  the  culture  on  the  left,  all 
plant  food  was  provided,  including  nitrogen. 

NITROGEN  IN  TOPS  AND  ROOTS  OF  LEGUMES 

From  data  already  given  it  will  be  seen  that  in  the  study  of 
immature  cowpeas  at  the  Illinois  Station,  the  infected  plants 
contained  only  14  per  cent  of  their  total  nitrogen  in  the  roots  with 
more  than  half  of  this  in  the  tubercles  themselves,  at  that  stage  of 
growth.  As  the  plants  approach  maturity,  the  tubercles  decay,  and 
only  the  shell,  or  outer  coat,  remains,  the  nitrogen  being  absorbed 
largely  by  the  host  plant,  but  in  some  part  evidently  by  companion 


ORGANIC   MATTER  AND   NITROGEN  219 

plants,  as  timothy  or  blue  grass,  whose  roots  may  come  in  contact 
with  the  decomposing  tubercles.  In  case  of  the  noninfected  cow- 
peas,  only  7  per  cent  of  the  nitrogen  was  found  in  the  roots  at  that 
stage  of  growth. 

Pot-culture  experiments  by  the  Dominion  of  Canada  Experiment 
Station,  with  plants  planted  May  20  and  harvested  August  4, 
showed  that  very  poorly  infected  horse  beans  contained  19  per 
cent  of  their  nitrogen  and  18  per  cent  of  their  organic  matter  in  the 
roots,  while  better  infected  plants  made  a  larger  yield  and  contained 
25  per  cent  of  their  nitrogen  and  also  25  per  cent  of  their  organic 
matter  in  the  roots;  whereas  well-infected  mammoth  red  clover 
contained  40  per  cent  of  its  nitrogen  and  35  per  cent  of  its  organic 
matter  in  the  roots. 

In  a  field  experiment  with  mammoth  clover,  seeded  with  barley 
in  the  spring  and  harvested  May  25  the  following  year,  the  Cana- 
dian Station  found,  per  acre,  123.8  pounds  of  nitrogen  in  the  tops 
and  48.5  pounds  in  the  roots,  to  a  depth  of  four  feet,  corresponding 
to  72  per  cent  in  the  tops  and  28  per  cent  in  the  roots. 

As  an  average  of  four  determinations  with  red  clover,  the  Con- 
necticut Station  found  28  per  cent  of  its  nitrogen,  35  per  cent  of 
its  phosphorus,  and  21  per  cent  of  its  potassium  in  the  roots  and 
stubble. 

As  an  average  of  two  determinations  by  the  Illinois  Station,  the 
red-clover  roots  found  in  the  surface  soil  (o  to  7  inches)  contained 
25  per  cent  of  the  total  nitrogen  of  the  plants,  while  only  one  per 
cent  of  the  total  was  contained  in  the  roots  in  the  subsurface  stra- 
tum (7  to  20  inches).  In  the  case  of  nearly  mature  cowpeas,  12 
per  cent  of  the  total  nitrogen  was  found  in  the  surface  roots  (o  to 
7  inches) ,  and  i  per  cent  in  the  subsurface  (7  to  20  inches) ;  and 
the  corresponding  figures  for  nearly  mature  soy  beans  were  8  per 
cent  and  i  per  cent. 

In  Table  34  are  recorded  the  data  from  an  Illinois  investigation 
of  sweet  clover,  in  which  determinations  were  made  of  the  total 
dry  matter  and  nitrogen;  (i)  in  the  tops  as  they  would  ordinarily  be 
cut  with  a  mower,  (2)  in  the  surface  residues,  consisting  of  stubble 
and  fallen  leaves  and  old  stems,  (3)  in  the  large  roots  in  the  plowed 
soil  to  a  depth  of  seven  inches,  (4)  in  the  smaller  roots  in  the 
plowed  soil,  and  (5)  in  the  roots  of  the  subsurface  stratum  from  7 


220        SYSTEMS   OF   PERMANENT   AGRICULTURE 


to  20  inches  in  depth.  The  investigation  was  made  when  the  sweet 
clover  was  full  grown  and  nearly  mature.  The  crop  was  started 
the  previous  season,  sweet  clover  being  a  biennial  plant. 

TABLE  34.   ILLINOIS  INVESTIGATIONS  OF  SWEET  CLOVER  (MELLILOTUS  ALBA) 


PARTS  OF  PLANT 

DEPTH 
(Inches) 

DRY  MATTER  PER  ACRE 

NITROGEN  PER  ACRE 

Pounds 

Per  Cent 
of  Total 

Pounds 

Per  Cent 

of  Total 

Tops  harvested  .     .     . 
Surface  residues      .     . 
Total  tops      .... 

9029 
1338 

174 
23 

10367 

8l 

197 

86 

Large  surface  roots 
Small  surface  roots 
Total  surface  roots 
Subsurface  roots     .     . 
Total  roots     .... 

o  to  7 
o  to  7 
o  to  7 
7  to  20 
o  to  20 

I568 
24I 

17 

5 

1809 
60  1 

14 

5 

22 
9 

10 

4 

2410 

J9 

31 

14 

Total  tops  and  roots       .... 

12777 

100 

228 

IOO 

It  will  be  seen  that  the  yield  of  sweet  clover  is  very  large,  amount- 
ing to  6.4  tons  of  total  dry  matter,  of  which,  however,  the  roots 
contain  only  1.2  tons  per  acre,  or  less  than  one  fifth  of  the  total. 
The  tops  of  sweet  clover  are  nearly  as  rich  in  nitrogen  as  full- 
grown  red  clover  (40  pounds  per  ton) ,  but  the  roots  contain  only 
one  seventh,  or  14  per  cent,  of  the  total  nitrogen.  Nearly  24  per 
cent  of  the  total  nitrogen  was  found  in  the  roots,  stubble,  and  sur- 
face residues  (largely  of  the  previous  season's  growth). 

The  sweet  clover  used  in  the  investigation  was  well  infected; 
but,  in  a  previous  experiment  on  the  same  soil  (brown  silt  loam 
prairie  of  the  early  Wisconsin  glaciation),  it  was  found  that  the 
yield  of  sweet  clover  was  almost  exactly  doubled  by  thorough 
inoculation,  and  the  percentage  of  nitrogen  in  the  infected  plants 
was  also  about  one  half  more  than  in  the  noninfected  plants, 
showing  that  on  this  soil  about  two  thirds  of  the  nitrogen  required 
for  this  large  crop  was  secured  from  the  air. 

While  sweet  clover  makes  a  fair  quality  of  hay,  if  cut  sufficiently 
early  in  its  growth,  and  is  also  used  for  pasture  with  some  success 


ORGANIC   MATTER  AND   NITROGEN 


221 


when  nothing  better  can  be  had,  it  is  not  to  be  compared  with 
red  clover  or  alfalfa  for  either  purpose,  but  it  does  give  promise 
of  great  value  as  a  green  manure  crop,  and  it  seems  appropriate 
to  emphasize  the  fact  that  the  6.4  tons  of  dry  matter  furnish  as 
much  humus-forming  material  and  as  much  nitrogen  as  would  be 
furnished  by  25  tons  of  average  farm  manure. 

In  the  Wisconsin  experiments  above  referred  to,  the  infected 
soy  beans  contained  in  their  roots  about  4  per  cent,  6  per  cent,  and 
5  per  cent,  of  their  nitrogen,  phosphorus,  and  potassium,  respec- 
tively; and  in  the  Michigan  experiments  the  corresponding  figures 
are  about  4  per  cent,  6  per  cent,  and  6  per  cent,  respectively. 

From  an  exhaustive  investigation  of  the  crimson-clover  plant 
(Trifolium  incarnatum) ,  Penny  (Delaware  Bulletin  67)  reports  the 
following  average  results'  for  fall-seeded  crops  harvested  about 
May  15,  when  nearly  in  full  bloom: 

TABLE  35.   COMPOSITION  OF  CRIMSON  CLOVER  IN  BLOOM 
Delaware  Experiments :  Pounds  per  Acre 


PARTS  OF  PLANT 

AIR-DRY 

MATTER 

NITROGEN 

PHOS- 
PHORUS 

POTASSIUM 

Tops,  pounds    .     

4CI2 

IO3 

76 

7O 

Roots,  pounds  

2O22 

41 

3-1 

IS 

Total,  pounds   

6S34 

144 

io.7 

8s 

PERCENTAGE  OF  TOTAL 


Tops,  per  cent  

60 

72 

71 

82 

Roots,  per  cent  '.  . 

21 

28 

20 

18 

The  proportions  were  found  to  vary  considerably,  but  this  gen- 
eral average  shows  the  crimson-clover  roots  (to  a  depth  of  24 
inches)  to  contain  less  than  one  third  of  the  organic  matter, 
nitrogen,  and  phosphorus,  and  less  than  one  fifth  of  the  potassium 
of  the  entire  plant.  It  was  found  that  77  per  cent  of  the  roots  were 
in  the  first  6  inches  of  soil,  and  1 3  per  cent  in  the  second  6  inches, 
7  per  cent  in  the  third,  and  3  per  cent  in  the  fourth  6  inches. 

In  Table  36  are  recorded  much  additional  information  concern- 


222 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


TABLE  36.   COMPOSITION  OF  PLANTS  (Tors  AND  ROOTS) 
Delaware  Experiment  Station :   Crops  seeded  July  22 


CROP,  AND 
DATE  OF 
HARVEST 

PARTS  OF  PLANT 

POUNDS  PER  ACRE  AND  PER  CENT 
IN  ROOTS 

Air-dry 
Matter 

Nitro- 
gen 

Phos- 
phorus 

Potas- 
sium 

Cowpeas 
Nov.  7 

Tops                       

3718 
301 

9 

65.2 
4-2 
.1 

7-2 
1.0 
.1 

39-2 
I.9 
.1 

Roots  o  to  8  inches  .  *  . 

Roots,  8  to  12  inches      .... 
Per  cent  in  roots    

8 

6 

13 

8 

Soy  beans 
Nov.  ii 

Tops             

6790 
717 
39 

130.9 
8.8 

•5 

I6-S 
1.0 

.0 

38.3 
1.4 
.1 

Roots  o  to  8  inches   

Roots,  8  to  12  inches      .... 
Per  cent  in  roots    

10 

6J 

5* 

4 

Vetch 
Nov.  19 

Tops   

3064 

584 
16 

108.0 

12.8 

•4 

9.8 

2.0 
.1 

65-i 

5-7 

.2 

Roots  o  to  8  inches   

Roots,  8  to  12  inches      ...     . 
Per  cent  in  roots 

17 

ii 

18 

8 

Crimson 
clover 
Nov.  20 

Tops   

5372 
38i 
32 

128.2 

5-7 
•5 

25-9 
.8 
.1 

69.7 
3-2 
•3 

Roots,  o  to  8  inches   

Roots,  8  to  12  inches      .... 
Per  cent  in  roots    

7 

6 

3* 

5 

Alfalfa 
Nov.  20 

TODS   . 

2267 
1972 
8 

54-8 
40.2 

.2 

5-7 
3-7 

.0 

26.7 

7-9 
.0 

Roots,  o  to  8  inches   

Roots,  8  to  12  inches      .... 
Per  cent  in  roots    

47 

42 

39 

23 

Red 
clover 
Nov.  22 

Tops   . 

2819 
1185 

27 

69.8 
32'5 

•7 

8-3 

4-3 
.1 

38.6 
8.0 

.2 

Roots,  o  to  8  inches   

Roots,  8  to  12  inches      .... 
Per  cent  in  roots    

3° 

32 

35 

18 

Cow-horn 
turnip 
Nov.  15 

Tops   

2565 
2902 

64.4 

44-7 

6.2 

5-1 

66.6 
Si.8 

Roots  

Per  cent  in  roots    

53 

4i 

45 

44 

Rape 
Nov.  1  6 

Tops   

5533 
864 

116.2 
13.2 

18.3 

2.2 

123.0 
10.9 

Roots,  o  to  8  inches   

Per  cent  in  roots    

*& 

IO 

II 

8 

ORGANIC   MATTER  AND   NITROGEN  223 

ing  the  composition  of  the  tops  and  roots  of  the  most  important 
field  legumes.  It  summarizes  a  series  of  investigations  by  Penny 
and  Close,  and  confirms  much  other  data  relating  to  these  crops 
and  bearing  directly  upon  the  problems  of  supplying  the  soil  with 
organic  matter  and  nitrogen. 

As  an  average  of  all  determinations,  it  is  safe  to  say  that  about 
one  third  of  the  nitrogen  of  the  red-clover  plant  is  contained  in  the 
roots  and  stubble,  and  that  the  growth  of  clover  above  ground 
contains,  before  rotting  or  leaching,  about  40  pounds  of  nitrogen 
to  the  ton  of  air-dry  substance. 

Alfalfa  contains  a  somewhat  larger  proportion  of  its  nitrogen  in 
the  roots,  at  least  during  the  first  year  of  its  growth;  and  possibly 
the  total  nitrogen  of  the  alfalfa  roots  would  average  one  half  as 
much  as  the  total  removed  in  the  crops,  even  when  the  plants  are 
several  years  old,  considering  the  entire  root  system,  which  com- 
monly reaches  a  depth  of  20  feet  or  more  with  old  plants.  Alfalfa 
hay  contains  50  pounds  of  nitrogen  per  ton. 

In  the  case  of  such  annuals  as  cowpeas  and  soy  beans,  not  more 
than  one  tenth  of  the  nitrogen  is  found  in  the  roots  and  stubble,  as 
a  rule.  The  crop  above  ground  contains  (when  thoroughly  air-dry) 
about  43  pounds  of  nitrogen  per  ton  for  cowpeas  and  about  53 
pounds  per  ton  for  soy  beans. 

Extensive  experiments  are  in  progress  in  Illinois  to  determine, 
under  actual  field  conditions,  what  systems  of  grain  farming  (with 
green  manures  and  crop  residues)  and  what  systems  of  independent 
live-stock  farming  will  increase  or  maintain  the  organic  matter 
and  nitrogen  of  the  soil;  but  these  are  investigations  that  require 
time,  and  but  few  results  have  as  yet  been  published. 

A  series  of  pot  cultures  has  been  reported  (Illinois  Bulletin 
115)  which  illustrates  the  fact  that  legume  green  manures  may 
take  the  place  of  commercial  nitrogen. 

The  soil  used  in  these  experiments  was  the  yellow  silt  loam  from 
the  unglaciated  area  of  southern  Illinois  (Pulaski  County),  which, 
as  will  be  seen  from  Table  15,  is  quite  deficient  in  nitrogen.  The 
field  from  which  this  soil  was  collected  had  been  under  cultivation 
for  about  75  years,  during  which  time  the  average  yield  of  wheat 
had  decreased  from  about  25  bushels  to  5  bushels  per  acre. 

In  the  pot-culture  experiments,  catch  crops  of  cowpeas  were 


224        SYSTEMS   OF   PERMANENT   AGRICULTURE 

planted  on  certain  pots  every  year  after  the  wheat  was  harvested, 
the  legumes  being  turned  under  before  sowing  wheat  for  the  next 
year. 

From  a  study  of  Table  98,  it  will  be  seen  that  practically  no  gain 
has  been  made  except  where  nitrogen  has  been  supplied,  either 
directly  in  commercial  form  or  indirectly  by  means  of  legume 
treatment.  It  should  be  borne  in  mind  that  no  legume  treatment 
preceded  the  1902  wheat  crop.  The  catch  crop  of  cowpeas  which 
was  planted  after  the  1902  wheat  crop  and  turned  under  later 
in  the  fall,  produced  a  marked  effect  upon  the  1903  wheat  crop. 
This  effect  became  more  marked  in  1904  and  1905,  when  every  pot 
receiving  legume  treatment  outyielded  the  pot  receiving  lime- 
nitrogen  treatment.  Previous  to  1905,  the  addition  of  phosphorus 
to  nitrogen  or  legume  treatment  always  increased  the  yield.  The 
addition  of  potassium  still  further  increased  the  yield  more  or 
less.  The  effect  of  both  phosphorus  and  potassium  has  been  less 
where  decaying  organic  matter  has  been  provided  in  the  legume 
treatment  than  where  the  nitrogen  has  been  supplied  in  commercial 
form  (dried  blood)  carrying  but  little  organic  matter. 

The  last  line  in  the  table  gives  the  yield  from  a  pot  of  virgin 
soil  collected  from  a  piece  of  unbroken  virgin  sod  land  adjoining 
the  cultivated  field  from  which  the  soil  in  all  the  other  pots  was 
taken. 

NITROGEN  FIXATION  BY  NONSYMBIOTIC  BACTERIA 

Aside  from  the  fixation  of  free  nitrogen  by  the  bacteria  living  in 
symbiotic  relationship  with  legume  plants,  there  are  at  least  three 
groups  of  bacteria  that  have  nitrogen-fixing  power  without  this 
relationship. 

First,  and  possibly  of  greatest  importance,  are  the  legume 
bacteria  themselves,  which  continue  to  fix  nitrogen  in  pure  cultures 
entirely  separated  from  legume  plants,  and  very  probably  also 
continue  thus  to  fix  some  nitrogen  in  the  soil,  even  after  the 
legume  plants  have  been  destroyed,  the  bacteria  drawing  their 
nutriment  from  the  decaying  organic  matter. 

Second,  is  the  anaerobic  group  of  bacteria  discovered  by  Wino- 
gradsky  in  1893,  and  called  Clostridium;  but  these  have  little 


ORGANIC   MATTER  AND   NITROGEN  225 

agricultural  significance,  because  they  develop  only  in  the  absence 
of  free  oxygen.  » 

Third,  is  the  azotobacter,  an  aerobic  group  described  by  Beijer- 
inck  in  1901,  of  which  Lipman  has  recently  found  some  additional 
species,  one  of  which  (Azotobacter  vinelandii)  appears  to  be  quite 
active  in  the  fixation  of  free  nitrogen  when  the  best  artificial  condi- 
tions are  provided.  (See  Lipman's  "  Bacteria  in  Relation  to  Coun- 
try Life,"  page  199.) 

Beijerinck  has  found,  "  as  a  result  of  improved  technique  for  the 
determination  and  study  of  the  distribution  of  the  organism,  that 
azotobacter  fixes  nitrogen,  and  that  there  is  a  distinct  relation 
between  the  distribution  of  this  organism  and  leguminous  plants." 
The  author  questions  if  there  may  not  be  a  relationship  between  the 
legume  bacteria  and  the  azotobacter.  (See  Experiment  Station 
Record,  1909,  Vol.  20,  page  920.) 

Whether  any  of  these  nonsymbiotic  bacteria  are  of  appreciable 
agricultural  importance  under  practical  conditions,  is  not  fully 
established.  It  is  known,  however,  that  a  supply  of  organic  matter 
is  essential  for  their  development,  and  the  organic  matter  of  the 
soil  which  must  be  decomposed  in  order  to  furnish  their  necessary 
supplies  of  carbonaceous  food  may  also  furnish  part  or  all  of  the 
nitrogen  which  they  require.  (See  also  pages  434-440.) 


CHAPTER  XV 

ROTATION    SYSTEMS    FOR   GRAIN   FARMING 

ABOUT  three  fourths  of  the  farmers  of  central  United  States  are 
so-called  grain  fanners.  There  has  always  been  a  large  proportion 
of  grain  farmers;  and,  furthermore,  there  always  will  be,  and  al- 
ways must  be,  for  the  world  does  not  live  by  meat  alone,  nor  even 
upon  meat  and  dairy  products;  bread  is  the  staff  of  life. 

Notwithstanding  these  well-known  facts,  whenever  the  grain 
farmer  of  central  United  States  has  asked  for  information  as  to 
how  he  could  maintain  the  fertility  of  his  soil,  the  reply  has  always 
been,  "  Become  a  live-stock  farmer."  While  this  may  or  may  not 
be  good  advice  for  the  individual  farmer,  it  is  certainly  not  good 
advice  for  all  the  farmers  of  the  state  or  nation. 

On  the  other  hand,  grain  farming  is  not  only  profitable,  —  and 
often  more  profitable  than  live-stock  farming,  —  but  there  are 
methods,  and  profitable,  practical  methods,  by  which  the  grain 
farmer  can  not  only  maintain  the  fertility  of  his  soil,  but  even  make 
it  more  productive  than  it  ever  was  even  in  its  virgin  state. 

Let  us  consider  the  simple  three-year  rotation:  (i)  corn,  (2) 
oats,  and  (3)  clover,  which  is  becoming  somewhat  common  in  the 
Illinois  corn  belt;  or  (i)  corn,  (2)  wheat,  and  (3)  clover,  the  most 
common  crop  rotation  of  Ohio.  Of  course,  as  many  fields  should 
be  provided  as  there  are  years  in  the  rotation,  so  that  every  crop 
may  be  represented  every  year. 

We  may  assume  yields  of  100  bushels  per  acre  of  corn  and  oats, 
50  bushels  of  wheat,  4  tons  of  clover,  and  4  bushels  of  clover  seed; 
or  these  yields  may  be  divided  by  two,  the  same  proportions  being 
maintained.  With  the  smaller  yields  the  corn,  oats,  and  clover 
seed  will  remove  86£  pounds  of  nitrogen;  while,  in  accordance  with 
the  average  data  thus  far  obtained,  we  may  count  that  the  clover 
secures  40  pounds  of  nitrogen  from  the  air  for  each  ton  of  hay  it 

226 


ROTATION   SYSTEMS   FOR   GRAIN   FARMING      227 

would  produce,  the  nitrogen  contained  in  the  roots  and  stubble 
being  no  more  than  that  furnished  by  the  ordinary  corn-belt  soil. 
If  the  two  regular  cuttings  would  make  two  tons  of  clover  hay; 
and  if  the  growth  of  clover  during  the  previous  season  (after  wheat 
or  oats  harvest)  and  during  the  autumn  (after  the  clover-seed 
harvest)  and  the  following  spring  (before  plowing  for  corn)  would 
make  another  half-ton  of  clover  hay,  or  two  and  one  half  tons  in 
all,  then  100  pounds  of  nitrogen  would  be  secured  from  the  air  to 
balance  the  86 \  or  89  pounds  removed  in  the  grain  and  seed. 
In  other  words,  from  13  to  15  per  cent  more  nitrogen  is  returned 
by  the  clover  than  is  removed  in  the  grain  and  seed. 

On  normal  soils  the  only  addition  to  this  system  that  is  neces- 
sary in  order  to  establish  a  permanent  agriculture  is  the  applica- 
tion of  20  pounds  of  phosphorus  for  the  lower  yields,  or  40  pounds 
for  the  larger  yields,  these  amounts  being  ample  to  replace  the 
phosphorus  removed  in  the  grain  and  seed  and  to  cover  all  possible 
loss  by  leaching.  For  the  smaller  yields,  200  pounds  per  acre  of 
steamed  bone  meal  or  200  pounds  of  raw  rock  phosphate  or  400 
pounds  of  acid  phosphate,  every  three  years,  will  be  more  than 
sufficient  to  maintain  the  phosphorus  content  of  the  soil;  and  twice 
these  quantities  would  be  ample  for  the  larger  yields  after  the 
productive  power  of  the  soil  has  been  raised  to  that  point.  To  do 
this  may  require  much  heavier  initial  applications  of  phosphorus, 
or  moderately  heavy  applications  for  the  first  four  or  five  rotations. 
Thus,  an  application  of  one  ton  of  good  rock  phosphate  (12^  per 
cent  phosphorus)  every  three  years  would  add  1250  pounds  of 
phosphorus  per  acre  in  15  years,  or  more  than  1000  pounds  above 
the  amount  removed  in  the  grain  or  seed  for  the  larger  yields  in 
the  rotation.  In  other  words,  the  phosphorus  content  of  the  aver- 
age Illinois  surface  soil  should  be  doubled  in  15  years  under  this 
system,  and  the  annual  cost  of  phosphorus  ($2.50)  would  be  no  more 
than  is  commonly  paid  by  farmers  in  the  Eastern  and  Southern 
states  for  so-called  "  complete "  fertilizers.  If  the  phosphorus 
applied  produced  increased  yields  of  7  bushels  of  corn  and  equiva- 
lent values  of  other  crops,  the  cost  would  be  covered  by  the  in- 
creased crops.  (See  actual  results  reported  in  later  pages.) 

This  system  requires  that  the  ears  of  corn  shall  be  husked  and 
the  stalks  returned  to  the  soil,  that  the  oat  straw  and  clover  straw 


228       SYSTEMS    OF   PERMANENT  AGRICULTURE 

shall  also  be  returned  to  the  land  after  threshing  out  the  grain  or 
seed,  and  that  the  regular  crop  of  clover  shall  be  mowed  and  left 
lying  on  the  land.  If  necessary,  to  prevent  too  rank  a  growth 
(which  might  smother  the  plants),  the  clover  may  be  mowed  twice 
before  the  seed  crop  is  allowed  to  grow. 

If  the  larger  yields  are  considered,  the  same  rotations  hold,  ex- 
cept that  the  richer  soil  would  very  possibly  furnish  a  larger  pro- 
portion of  the  nitrogen  required  by  the  clover  plant. 

With  some  modifications,  these  two  three-year  rotations  may  be 
combined  in  a  six-year  rotation  of  (i)  corn,  (2)  corn,  (3)  oats, 
(4)  clover,  (5)  wheat,  and  (6)  clover,  which  avoids  the  necessity 
of  seeding  wheat  on  the  corn  ground,  a  task  sometimes  difficult 
to  accomplish.  If  necessary,  this  may  be  reduced  to  a  five-year 
rotation,  either  by  omitting  one  corn  crop,  or  by  plowing  under  the 
clover  in  the  spring  of  the  fifth  year  as  late  as  practicable  for  corn. 
With  the  former  change  it  will  be  less  difficult,  and  with  the  latter 
more  difficult,  to  maintain  the  nitrogen,  than  with  the  six-year 
rotation. 

A  four-year  rotation,  which  the  author  prefers  for  the  general 
conditions  in  the  North  Central  states,  includes  the  four  crops, 
wheat,  corn,  oats  (or  barley),  and  clover,  in  the  order  given. 
Clover  should  also  be  seeded  on  the  young  wheat  in  the  early  spring, 
and  plowed  under  (after  disking,  if  necessary  to  insure  capillary 
connection)  as  late  as  practicable  the  next  spring  before  planting 
corn.  In  grain  farming  only  the  seed  crop  of  clover  is  removed 
from  the  land,  and  the  phosphate  is  plowed  under  with  the  clover 
residues  for  the  wheat.  All  of  the  threshed  straw  (from  wheat, 
oats,  and  clover)  is  hauled  from  the  threshing  directly  to  the  field, 
where  it  may  be  thrown  off  in  windrows,  and  soon  afterward  spread 
over  the  land  as  uniformly  as  necessary.  It  may  be  used  for  a  top 
dressing  for  wheat,  or  it  may  be  applied  in  moderate  amounts  to 
the  land  from  which  wheat  has  been  harvested,  where  the  young 
clover  is  growing  as  a  green  manure  for  the  following  corn  crop. 
Judgment  must  always  be  exercised  in  the  matter  of  applying 
large  amounts  of  straw,  or  of  plowing  under  heavy  crops,  or  applica- 
tions of  coarse  material,  which  may  do  damage  if  turned  under 
too  late  in  the  spring,  especially  if  the  season  is  dry  or  if  the  soil  is 
deficient  in  lime. 


ROTATION   SYSTEMS   FOR   GRAIN   FARMING      229 

For  southern  Illinois  and  other  Southern  states,  a  four-year  rota- 
tion of  (i)  corn,  (2)  cowpeas  (or  soy  beans),  (3)  wheat  (or  oats), 
and  (4)  clover  is  very  satisfactory;  and  a  three- year  rotation, 
in  which  it  is  more  difficult  to  maintain  the  nitrogen,  is  (i)  wheat, 
(2)  corn,  and  (3)  cowpeas;  or  (i)  cotton,  (2)  corn  and  cowpeas, 
and  (3)  oats  and  cowpeas,  in  either  of  which  soy  beans  may  be  sub- 
stituted, and  should  be  substituted  in  case  of  danger  from  cowpea 
wilt  or  other  disease;  and  similarly,  alsike  or  sweet  clover  may  be 
sometimes  substituted  for  red  clover  in  case  of  clover  sickness, 
which  is  more  fully  discussed  later  on.  In  these  rotations  consider- 
able use  can  be  made  of  legume  catch  crops.  Thus  red  clover  or 
sweet  clover  may  be  started  with  the  wheat  and  plowed  under  the 
following  spring  as  green  manure  for  corn,  or  cowpeas  can  be  grown 
after  the  wheat  is  harvested.  Clover  or  vetch  or  cowpeas  (or  a 
mixture  of  legumes)  can  be  seeded  in  the  corn  at  the  time  of  the 
last  cultivation  and  plowed  under  late  the  following  spring  before 
seeding  the  regular  cowpea  crop;  and,  where  cotton  is  to  follow, 
some  legume  catch  crop  could  be  seeded  after  the  regular  cowpea 
crop  is  harvested,  allowed  to  grow  during  the  late  fall,  winter,  and 
early  spring,  and  plowed  under  for  cotton. 

If  necessary,  not  only  the  cotton  stalks,  but  also  the  cotton  seed 
may  be  returned  to  the  land,  the  lint  of  itself  being  of  much  greater 
value  than  any  grain  crop.  (Two  bales  of  cotton,  or  1000  pounds 
of  lint,  worth  $100,  is  no  larger  crop,  comparatively,  than  100 
bushels  of  corn,  worth  $40,  as  a  ten-year  average  price  in  Illinois.) 

Any  one  who  is  familiar  with  agricultural  practice  can  estimate 
closely  the  probable  or  possible  crop  yields,  and  with  the  yields 
determined  and  with  the  disposition  of  the  crops,  catch  crops,  and 
crop  residues  decided  upon,  any  one  can  compute  very  closely 
from  the  data  given  in  Table  23  as  to  the  probable  maintenance 
of  the  nitrogen  supply. 

Two  factors  of  opposite  effect  —  (i)  the  loss  of  nitrogen,  espe- 
cially by  leaching,  and  (2)  the  addition  of  nitrogen  in  rain  and  by 
fixation  of  free  nitrogen  independent  of  legume  plants,  especially 
by  the  azotobacter  (factors  which  tend  to  counterbalance  each 
other)  —  are  discussed  on  another  page. 

From  all  of  the  facts  it  will  be  understood  that  there  is  just  as 
much  reason  and  as  much  satisfaction  in  computing  that  a  50- 


230       SYSTEMS    OF   PERMANENT   AGRICULTURE 

bushel  crop  of  corn  removes  from  the  soil  74  pounds  of  nitrogen  arid 
that  eight  tons  of  average  manure,  or  two  tons  of  clover,  plowed 
under  will  return  80  pounds  of  nitrogen  to  the  soil,  as  there  is  in 
estimating  the  quantity  of  corn  and  hay  that  will  be  required  to 
feed  a  car  load  of  steers  for  eight  months. 

The  average  American  grain  farmer  "  changes  "  his  crops  more 
or  less  by  occasionally  substituting  oats  or  barley  for  corn  or 
wheat.  He  rarely  even  plows  under  a  catch  crop  of  clover,  often 
burns  his  straw  and  corn  stalks,  and  makes  almost  no  effort  to 
restore  to  the  soil  the  fertility  removed  in  crops.  The  supply  of 
active  organic  matter  rapidly  decreases..  Consequently  the  land 
soon  reaches  a  condition  of  low  productiveness,  and  he  is  correctly 
termed  a  "  soil  robber."  He  knows  his  soil  is  running  down,  but 
he  hopes  it  will  last  as  long  as  he  does. 

The  average  live-stock  farmer  is  forced  to  keep  more  or  less  of 
his  land  in  meadow  and  pasture,  and  in  the  residues  and  grass 
and  clover  roots  supplies  some  fresh  organic  matter,  which,  as  it 
decays,  hastens  the  decomposition  of  the  old  humus  and  also  the 
liberation  of  mineral  elements  from  the  soil.  By  these  means  and 
by  the  better  avoidance  of  insect  injuries  and  plant  diseases,  he 
produces  larger  crops  when  corn  or  other  grains  are  grown,  which 
may  reduce  the  fertility  of  his  soil  even  more  rapidly  than  the 
smaller  crops  of  the  grain  farmer;  but  he  does  not  know  it,  and, 
as  he  makes  a  good  show  on  new,  rich  land  for  two  generations  or 
more,  he  is  incorrectly  held  up  as  a  "  soil  builder."  In  actual 
practice  most  of  the  farm  rarely,  if  ever,  receives  an  application  of 
manure.  "  Farm  manure  is  good  enough,  but  there's  not  enough 
of  it "  is  the  common  report  of  experienced  live-stock  farmers. 
This  inadequacy  of  the  manure  supply  is  due  not  only  to  the  large 
destruction  of  organic  matter  when  fed  to  animals,  but  also  in  part 
to  unavoidable  losses  of  manure  and  in  part  to  unnecessary  waste. 

In  planning  systems  of  permanent  agriculture  of  wide  applica- 
tion, a  distinction  should  be  kept  in  mind  between  the  ordinary 
live-stock  farmer,  who  markets  his  own  farm  produce  in  the  form 
of  meat,  wool,  or  dairy  products,  and  the  stock  breeder,  who  sells 
breeding  animals  at  higher  prices,  or  the  stock  feeder,  who  often 
buys  both  stock  and  feed  and  is  to  that  extent  not  a  farmer  but  a 
manufacturer. 


CHAPTER  XVI 

LIVE-STOCK   FARMING 

IF  a  four-year  rotation  is  practiced,  including  two  crops  of  corn, 
followed  by  oats,  with  clover  seeded  the  third  year,  and  clover  for 
hay  and  pasture  the  fourth  year,  and  all  crops  used  for  feed  and 
bedding,  the  nitrogen  balance  can  be  determined  by  simple  com- 
putations based  upon  facts  established  within  narrow  limits  by 
such  data  as  have  been  cited  in  the  preceding  pages.  We  may 
assume  5o-bushel  crops  of  corn  and  oats,  and  i^  tons  of  hay  in  the 
first  cutting,  with  i  ton  additional  for  all  previous  and  subsequent 
growth,  the  same  as  for  the  grain  system;  or  here,  too,  we  may 
double  the  assumed  yields  and  maintain  the  same  proportions. 
With  the  lower  yields  the  three  grain  crops  and  the  i^  tons  of 
clover  hay  would  contain  256  pounds  of  nitrogen.  Under  the 
most  careful  system  of  saving  manure,  three  fourths  of  this,  or  192 
pounds,  can  be  returned  directly  to  the  land,  and  to  this  may  be 
added  30  pounds  of  nitrogen  added  to  the  soil  in  the  manure  from 
the  one  ton  of  pastured  clover,  making  222  pounds  added  by  pastur- 
ing and  manuring.  If  we  consider  that  the  nitrogen  contained  in 
the  clover  hay  was  taken  from  the  air,  the  real  draft  upon  the  soil 
is  only  196  pounds.  In  this  system  about  13  per  cent  more  nitro- 
gen is  returned  in  the  manure  and  pasture  than  is  removed  from 
the  soil  by  the  three  grain  crops. 

If  the  rotation  is  extended  to  five  years  by  sowing  clover  and 
timothy  and  pasturing  the  fifth  year,  assuming  the  growth  to  be 
three  fourths  clover  the  fourth  year  and  the  pasture  herbage  to 
be  only  one  fourth  clover  the  fifth  year,  the  outcome  with  respect 
to  nitrogen  would  be  256  pounds  removed  from  the  soil  and  267 
pounds  returned  in  the  manure  and  pasture  droppings  during  the 
five  years,  if  we  disregard  the  strong  probability  that  timothy, 
growing  as  a  companion  crop,  secures  some  portion  of  its  nitrogen 
from  the  decaying  tubercles  of  the  clover  roots. 

231 


232 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


If  we  assume  that  three  fourths  of  the  produce  harvested  is  used 
for  feed  and  one  fourth  for  bedding,  and  that  one  third  of  the  or- 
ganic matter  consumed  by  animals  is  recovered  in  the  manure  or 
droppings,  then  the  four-year  rotation  under  live-stock  farming 
would  add  organic  matter  to  the  soil  at  the  rate  of  i^  tons  a  year, 
while  the  three-year  rotation  of  corn,  oats,  and  clover,  under  the 
grain  system,  would  add  organic  matter  at  the  rate  of  if  tons  a 
year. 

Thus,  it  will  be  seen  that  the  grain  system  under  a  three-year 
rotation  of  corn,  oats,  and  clover,  or  of  corn,  wheat,  and  clover,  or 
under  a  four-year  rotation  of  wheat  (and  clover),  corn,  oats  (or 
barley),  and  clover;  or  under  a  six-year  rotation  of  corn,  corn, 
oats,  clover,  wheat,  and  clover,  will  maintain  the  nitrogen  as  well, 
and  the  humus,  or  organic  matter,  somewhat  better,  than  the  live- 
stock system  under  the  four-year  rotation  of  corn,  corn,  oats,  and 
clover,  or  under  the  five-year  rotation  of  corn,  corn,  oats,  clover, 
and  timothy,  with  all  produce  either  harvested  or  pastured. 

Furthermore,  the  most  uncertain  feature  in  these  methods  is  in 
regard  to  saving  the  manure.  The  computations  here  given  pro- 
vide for  practically  no  loss  of  solid  or  liquid  excrement,  for  no  loss 
by  fermentation  or  fire-fanging,  which  may  occur  even  under 
cover,  and  for  no  loss  by  leaching  of  manure  exposed  to  the  weather 
in  the  open  barnyard.  It  is  common  knowledge  that  a  large  part 
of  the  value  of  manure  is  frequently  lost  before  it  is  applied  to  the 
land. 

The  author  has  diligently  inquired  at  many  farmers'  meetings 
for  several  years  for  a  man  who  had  applied  manure  made  from 
crops  grown  on  his  own  farm  to  all  of  the  cultivated  land  on  a  160- 
acre  farm,  —  not  to  all  during  one  year  or  during  one  rotation,  but 
even  during  all  the  time  he  had  farmed  the  land.  Very  few  men 
have  been  found  who  could  answer  that  all  of  their  cultivated 
land  had  been  thus  manured,  —  not  more  than  one  in  a  thousand. 

In  nearly  all  sections  of  the  country  a  farmer  can  be  found,  here 
and  there,  —  sometimes  one  in  ten,  and  sometimes  only  one  in  a 
hundred,  —  who  feeds  all  the  crops  he  raises  and  also  all  that  he 
can  buy  at  reasonably  low  prices  from  his  neighbors,  who  supple- 
ments all  this  with  more  or  less  purchased  bran  and  shorts,  oil 
meal,  cotton-seed  meal,  etc.,  and  who  is  thus  able  to  produce  sufn- 


LIVE-STOCK  FARMING  233 

cient  manure  of  good  quality  to  maintain  or  even  to  increase  the 
fertility  of  his  own  farm. 

In  specially  favored  localities,  a  few  farmers  haul  manure  from 
town,  or  even  ship  it  from  the  larger  cities,  especially  for  use  in 
market  gardening,  and  they,  too,  are  thus  enabled  to  enrich  their 
lands  at  the  expense  of  many  other  farms;  but  no  extensive  state 
or  nation  ever  has  or  ever  can  maintain  sufficient  live  stock;  even 
in  country  and  city  combined,  to  furnish  manure  with  which  to 
maintain  the  productive  power  of  all  the  farm  lands. 

Even  under  the  best  system  of  independent  live-stock  farming; 
that  is,  without  dependence  upon  the  purchase  of  supplementary 
food  stuffs  or  the  use  of  manure  from  town,  it  is  necessary  to  pur- 
chase and  apply  some  phosphorus  in  order  to  replace  that  sold  in 
the  animals  and  animal  products,  butter  and  cream  being  the  only 
important  farm  products  that  do  not  contain  appreciable  amounts 
of  phosphorus. 

In  order  to  increase  the  phosphorus  content  of  normal  soils, 
phosphorus  should  be  applied  in  live-stock  farming  the  same  as 
in  grain  farming,  but  to  merely  replace  that  sold  in  animal  products 
will  require  applications  of  only  one  half  as  much  phosphorus  as 
is  required  for  grain  farming,  assuming  that  all  of  the  grain  and 
clover  and  part  of  the  corn  stover  and  oat  straw  are  eaten  by  the 
live  stock.  Thus,  for  the  larger  yields,  the  loss  of  phosphorus 
would  be  about  20  pounds  per  acre  in  four  years  with  live-stock 
farming,  and  30  pounds  in  three  years  with  grain  farming,  as  can 
readily  be  determined  by  computation  from  the  data  given  in 
Table  23  and  the  results  of  the  digestion  and  feeding  experiments 
with  dairy  cows  by  the  Illinois  Station,  with  dairy  cows  and  steers 
at  the  Pennsylvania  Station,  and  with  sheep  at  the  Ohio  Station, 
from  which  we  must  conclude  that  as  an  average  at  least  one  fourth 
of  the  phosphorus  contained  in  the  feed  is  not  recovered  in  the 
manure. 

In  comparison  with  these  permanent  systems  of  agriculture,  it  is 
worth  while  to  compute  the  results  of  a  four-year  rotation  of  three 
crops  of  corn  and  one  of  oats,  seeded  with  clover  to  be  plowed  under 
the  next  spring,  assuming  that  the  corn  is  husked  and  the  stalks 
burned  (except  the  third  year,  when  the  stalks  are  disked  down  for 
oats),  that  the  oat  crop  is  all  removed,  and  that  the  total  growth 


234        SYSTEMS   OF   PERMANENT   AGRICULTURE 

of  clover  would  equal  one  ton  of  hay  per  acre.  This  will  be  recog- 
nized as  the  "  best  "  common  system  of  grain  farming  followed  in 
past  years  in  the  heart  of  the  corn  belt.  And  not  infrequently  the 
live-stock  farming  has  been  like  unto  it,  except  that  the  corn 
stalks  have  been  pastured  before  being  burned  or  disked  down, 
the  clover  has  been  pastured  the  first  fall,  cut  for  hay  the  next 
summer,  and  pastured  again  before  plowing  for  corn,  and  10  loads 
per  acre  of  rotted  and  leached  manure  have  been  applied  occa- 
sionally to  the  high  places,  where  the  land  is  getting  thin  and  where 
the  clover  fails  to  catch. 

Another  most  significant  fact  should  be  considered  in  this  com- 
parative study  of  grain  farming  and  live-stock  farming;  namely, 
that  1000  bushels  of  grain  has  at  least  five  times  as  much  food 
value  and  will  support  five  times  as  many  people  as  will  the  meat 
or  milk  that  can  be  made  from  it.  (Not  more  than  one  fifth  of  the 
nitrogen  consumed  in  the  food  of  animals  is  retained,  as  a  rule,  in 
the  milk  or  other  edible  animal  products,  and  the  proportion  saved 
of  carbonaceous  food  is  usually  still  less.) 

In  his  American  lectures  on  the  "  Agricultural  Investigations  at 
Rothamsted,  England,  during  a  Period  of  Fifty  Years,"  which 
were  published  as  Bulletin  22,  Office  of  Experiment  Stations, 
United  States  Department  of  Agriculture,  Sir  Henry  Gilbert 
"  summarizes  the  results  of  very  numerous  experiments  "  conducted 
at  Rothamsted  with  growing  and  fattening  cattle,  sheep,  and  swine. 
From  this  summary  we  obtain  the  following  data: 

DISPOSITION  OF  100  POUNDS  OF  DRY  SUBSTANCE  IN  FOOD  CONSUMED 
Summary  of  Rothamsted  Feeding  Experiments 


ANIMALS  USED  IN  EXPERIMENTS    .        . 

CATTLE 

SHEEP 

SWINE 

Dry  substance  found  in  animal  increase,  pounds   .     . 

6.2 

8.0 

I7.6 

Dry  substance  found  in  excrements,  pounds  .     .     .     . 

36.5 

31.9 

I6.7 

Dry  substance  destroyed  by  the  animal,  pounds  .     .     . 

57-3 

60.  i 

65-7 

Average  per  cent  of  fat  in  the  fat  animal       .... 

3° 

33 

44 

Thus,  a  large  proportion  of  the  food  digested  is  destroyed  by 
the  animal  and  must  be  exhaled  or  thrown  off  as  carbon  dioxid, 
water,  urea,  etc.  Of  the  small  percentage  of  the  food  that  is 


LIVE-STOCK   FARMING  235 

actually  retained  in  the  animal  tissues,  only  one  half  to  two 
thirds  may  serve  as  human  food,  after  discarding  the  offal  and  non- 
edible  parts.  On  the  other  hand,  the  carbohydrates  of  the  food 
contribute  largely  to  the  formation  of  animal  fat,  the  energy  value 
of  which  is  about  2^  times  that  of  carbohydrates;  so  that,  in  case 
of  fat  swine,  the  edible  food  produced  is  equivalent  to  about  20 
per  cent  of  the  dry  substance  in  the  ration  consumed  by  the  ani- 
mal; while,  in  the  production  of  fat  cattle,  less  than  10  per  cent  of 
the  dry  matter  in  the  ration  consumed  is  represented  in  the  human 
food  produced. 

These  data  do  not  answer  questions  as  to  the  comparative  value 
of  vegetable  and  animal  food  for  human  nutrition;  but  50  cents 
for  a  piece  of  steak,  with  10  cents  for  potatoes,  and  no  extra  charge 
for  bread,  must  roughly  represent  the  relative  cost  of  the  materials; 
and  perhaps  the  vegetarian  would  hold  that  the  steak  might  as 
well  be  replaced  by  peas  or  beans  costing  10  or  15  cents. 

With  all  of  these  facts  considered,  it  seems  evident  that  live- 
stock farming  must  and  should  continue  to  decrease,  except  on 
rough  lands  not  suited  to  cultivation,  in  semiarid  sections  where 
the  average  produce  is  not  worth  harvesting  otherwise,  or  in  espe- 
cially favored  sections  near  the  cities  where  dairy  farming  is 
profitable  and  may  easily  be  made  permanent  because  of  the  addi- 
tion of  manure  hauled  from  town  or  made  from  purchased  feeds. 

It  should  be  understood,  however,  that  America  still  produces  a 
large  surplus  of  grain  suitable  for  human  food,  and  for  some  years 
to  come  more  or  less  of  this,  especially  of  corn,  will  be  most  profit- 
ably marketed  through  the  production  of  live  stock.  For  the 
live-stock  farmer,  all  must  agree  with  the  following  statement 
from  Mumford's  "  Beef  Production"  (page  13): 

"When  we  remember  that  the  production  of  manure  of  the  looo-pound 
steer  for  a  six-months'  feeding  period  varies  from  three  to  four  tons,  we  can 
appreciate  what  a  factor  farmyard  manure  may  become  in  increasing  the 
revenues  of  the  farm,  and  that  profits  and  losses  in  cattle  feeding  should  not 
stop  with  a  consideration  of  the  cost  of  cattle  and  feed  and  their  selling 
price." 


CHAPTER   XVII 

THE  USE  OF  PHOSPHORUS   IN  DIFFERENT  FORMS 

HAVING  determined  how  to  correct  soil  acidity  (when  necessary) 
and  how  to  keep  the  soil  sweet,  by  means  of  ground  limestone; 
having  determined  how  to  maintain  or  increase  the  supply  of  or- 
ganic matter  and  nitrogen  in  the  soil,  by  means  of  farm  manure 
in  live-stock  farming,  or  by  means  of  legume  crops  and  catch  crops 
and  crop  residues  in  grain  farming,  or  by  a  combination  of  these  in 
mixed  or  diversified  farming,  which  is  sometimes  preferable  and 
more  profitable  than  either  alone;  and  having  determined  the 
absolute  necessity  of  maintaining  or  increasing  the  supply  of  phos- 
phorus in  the  soil  by  direct  applications  exceeding  the  amounts 
removed  in  crops  harvested,  —  the  next  most  important  question, 
and  the  only  remaining  exceedingly  important  question,  is,  What 
form  or  forms  of  phosphorus  shall  be  used? 

There  are  four  general  sources  of  phosphorus  for  use  in  soil 
improvement:  (i)  farm  manure,  (2)  bone  meal,  (3)  phosphate 
rock,  and  (4)  basic  slag  phosphate. 

The  first  two  are  themselves  farm  products,  and  at  the  best  only 
provide  that  the  phosphorus  taken  from  the  soil  shall  be  returned 
to  the  soil,  and  if  there  is  any  loss  whatever,  the  ultimate  effect, 
applied  to  the  state  or  country  as  a  whole,  must  be  a  reduction 
in  the  general  average  fertility  of  the  soil. 

To  supply  to  a  40-acre  field  1000  pounds  of  phosphorus  (25 
pounds  per  acre)  in  the  form  of  manure  made  from  purchased  corn, 
would  require  an  investment  of  more  than  $3000  at  40  cents  a 
bushel  for  corn.  While  the  purchase  of  grain  and  other  food  stuffs 
provides  a  method  by  which  soils  can  be  positively  enriched  in 
phosphorus,  and  while  there  is  usually  more  or  less  profit  from  feed- 
ing, so  that  the  phosphorus  thus  obtained  may  really  cost  nothing 
in  the  end,  nevertheless,  it  is  worth  while  to  keep  in  mind  that  this 
method  requires  large  capital,  special  equipment,  such  as  buildings, 

236 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS      237 

water  supply,  and  fences,  and  some  knowledge  and  skill  in  the  live- 
stock line,  including  business  ability  in  the  purchase  and  sale  of 
stock  and  animal  products,  in  addition  to  the  requirements  for  the 
production  of  crops. 

The  addition  of  phosphorus  in  farm  manures  is  undoubtedly 
one  of  the  best  methods  for  those  who  are  able  to  practice  it,  and 
by  use  of  liberal  proportions  of  grain  and  other  concentrates  rich 
in  phosphorus,  especially  bran  from  different  grains,  cake  or  meal 
from  various  seeds  from  which  the  oil  has  been  expressed,  very 
considerable  amounts  of  phosphorus  are  added.  It  is  important, 
however,  to  understand  and  to  keep  in  mind  that  average  farm 
manure  is  poor  in  phosphorus  in  comparison  with  its  content  of 
nitrogen  and  potassium,  especially  when  made  from  the  produce 
that  remains  after  part  of  the  grain  has  been  sold  from  the  farm, 
and  more  especially  when  used  in  connection  with  a  rotation  in- 
cluding legume  crops  and  on  soils  abundantly  supplied  with  po- 
tassium but  poor  in  phosphorus.  In  other  words,  under  such  con- 
ditions average  farm  manure  is  a  very  poorly  balanced  fertilizer, 
and  if  used  even  in  moderate  quantities  the  production  of  stalks 
or  straw  is  likely  to  be  excessive  in  comparison  with  the  yield  of 
grain;  and  the  small  grains  are  also  likely  to  lodge,  because  the 
unbalanced  ration  produces  weakness  even  in  straw  of  large  growth. 

Considering  the  more  concentrated  phosphorus  products,  there 
are  four  classes  to  be  kept  in  mind:  (i)  natural  bone,  (2)  natural 
rock  phosphate,  (3)  basic  slag  phosphate,  and  (4)  acid  phosphate. 

In  the  first  group  are  raw  bone  meal,  steamed  bone  meal,  bone 
tankage,  and  phosphatic  guanos.  In  the  second  group  are  the  va- 
rious natural  mineral  phosphates,  as  the  hard  and  soft  phosphates 
of  Florida,  the  land  rock  and  pebble  phosphate  of  South  Carolina, 
the  brown  and  blue  phosphates  of  Tennessee,  and  the  apatite  of 
Canada.  The  third  group  consists  of  basic  slag  only,  sometimes 
called  Thomas  phosphate.  The  fourth  group  includes  all  acidulated 
phosphates,  such  as  acidulated  bone  meal,  acidulated  bone  black, 
acidulated  bone  ash,  common  acid  phosphate,  and  double  super- 
phosphate. The  term  dissolved  is  often  used  for  acidulated  goods. 

Non-acidulated  bone  black  and  bone  ash  are  best  considered  as 
belonging  to  the  second  group  with  the  natural  mineral  phosphates- 

In  groups  i  and  2,  the  phosphorus  is  present  chiefly  in  the  same 


238        SYSTEMS   OF   PERMANENT   AGRICULTURE 

compound,  tricalcium  phosphate,  Ca3(PO4)2,  the  difference  be- 
tween these  two  groups  being  the  presence  of  more  or  less  organic 
matter  within  the  pores  of  the  bone,  while  the  products  in  group  2 
contain  little  or  no  organic  matter.  In  group  3  the  phosphorus 
is  contained  in  a  basic  or  alkaline  compound  or  mixture,  and  in 
group  4  the  phosphorus  exists  chiefly  in  monocalcium  phosphate, 
an  acid  salt.  This  form  of  phosphorus  is  soluble  in  water,  and  even 
the  dicalcium,  or  "  reverted,"  phosphate  is  soluble  in  very  weak 
solvents  (as  in  neutral  ammonium  citrate  solution) ;  while  all  prod- 
ucts in  groups  i,  2,  and  3,  are  known  as  insoluble  forms  of  phos- 
phorus. 

About  seventy  years  ago  Sir  John  Lawes,  independent  of  a 
suggestion  previously  made  by  Liebig,  treated  bone  meal  with 
sulfuric  acid  and  formed  an  acid  phosphate  that  proved  of  greater 
benefit  to  the  turnip  crop  grown  on  the  Rothamsted  soils  than 
the  crushed  bone  or  coarse  bone  meal  then  in  use;  and  in  1842 
a  patent  was  taken  out  by  him  for  treating  mineral  phosphates 
with  sulfuric  acid  in  order  to  increase  their  availability  in  crop 
production. 

Acidulated  bone  meal  has  been  much  used  as  a  fertilizer,  but 
gradually  its  use  has  given  way,  largely  because  the  most  success- 
ful and  influential  farmers  in  our  Eastern  states  have  insisted  that 
in  the  long  run  fine-ground  pure  raw  bone  meal  was  more  profit- 
able than  acidulated  bone.  It  is  always  recognized  that  the  acidu- 
lated bone  gave  the  best  results  the  first  year,  but,  on  the  basis  of 
equal  cost,  the  raw  bone  proved  much  more  durable,  and  hence, 
more  profitable  in  the  end,  especially  where  good  rotations  were 
practiced  and  some  effort  made  to  keep  the  soil  supplied  with 
organic  matter. 

In  more  recent  years  steamed  bone  meal  is  replacing  the  raw 
bone,  because,  as  a  rule,  it  gives  better  results,  due  in  part  to  its 
larger  phosphorus  content  and  in  part  to  the  fact  that  it  is  usually 
more  finely  ground  than  the  raw  bone.  There  are  still  to  be  found 
those  who  argue  that  "  if  one  wishes  to  benefit  himself,  he  should 
use  acidulated  phosphates,  but  if  he  wishes  to  benefit  his  grand- 
children, he  should  use  bone."  However,  the  farmers'  demand 
for  "  pure  raw  bone  "  and  for  "  steamed  bone  meal  "  continues  to 
increase,  and  this  steady  demand  is  based  upon  long- continued 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     239 

experience  in  the  practice  of  agriculture.  These  products  are 
everywhere  looked  upon  as  safe  fertilizers.  They  never  injure  the 
soil,  and  where  most  used  they  are  classed  with  farm  manure  in 
that  regard.  And  this  is  a  correct  view,  for  farm  manure  and  bone 
are  two  important  products  from  the  same  source.  In  other  words, 
from  the  fertility  standpoint,  animals  separate  crops  roughly 
into  manure  and  bone,  and  if  we  return  the  bone  with  the  manure, 
we  thus  return  practically  all  of  the  fertility  removed  by  the  crop, 
except  a  part  of  the  nitrogen,  which  it  is  not  necessary  to  return 
directly,  because  the  legumes  are  able  to  secure  it  from  the  air. 

Basic  slag  phosphate,  a  by-product  in  the  manufacture  of  steel 
from  pig  iron  containing  considerable  quantities  of  phosphorus, 
has  been  used  as  a  phosphorus  fertilizer  since  1882. 

Recent  investigations1  by  Director  Hall  of  Rothamsted  have  con- 
vinced him  that  the  typical  phosphorus  compound  in  basic  slag 
is  a  double  phosphate  and  silicate  of  calcium  of  the  composition 
Ca3(CaO)  (PO4)2CaSiO3,  but  the  more  common  teaching  has  been 
that  a  tetracalcium  phosphate,  Ca3(CaO)  (PO4)2,  exists  in  the  slag. 
In  any  case  the  slag  contains  very  considerable  proportions  of 
lime,  which  undoubtedly  greatly  assists  in  the  disintegration 
of  the  product  after  being  incorporated  with  the  soil,  thus  bringing 
the  phosphate  into  an  extremely  finely  divided  state.  The  presence 
of  lime  in  the  slag  is  of  itself  of  some  benefit  on  certain  soils,  al- 
though as  a  source  of  lime  it  is,  of  course,  very  expensive  and  very 
insignificant,  compared  to  ground  limestone. 

The  use  of  slag  phosphate  is  quite  likely  to  give  disappointing 
results  for  the  first  year  or  two,  resembling  natural  bone  in  this 
regard;  but  like  bone,  also,  it  gives  very  satisfactory  results  with 
continued  use,  and  no  prejudice  has  developed  regarding  its  use 
on  account  of  any  supposed  injury  to  the  soil. 

Herbert  Ingle,  in  his  "Manual  of  Agricultural  Chemistry," 
makes  the  following  significant  statements  (page  162): 

"Many  attempts  to  improve  basic  slag  as  a  manure  have  been  made,  some 
directed  to  the  removal  of  the  iron,  others  the  sulfur,  while  others  have  attempted 

1  This  statement  is  based  upon  the  information  given  by  Director  Hall  in  con- 
nection with  his  course  of  lectures  before  the  Graduate  School  of  Agriculture  of  the 
Association  of  American  Agricultural  Colleges  and  Experiment  Stations,  held  at 
Cornell  University,  July,  1908.  His  final  conclusions  should  not  be  assumed  in 
advance  of  publication  by  him. 


240       SYSTEMS   OF   PERMANENT   AGRICULTURE 

to  render  the  phosphorus 1  more  soluble,  by  treatment  with  sulfuric  acid.  Prac- 
tically all  these  attempts  have  been  abandoned,  and  the  only  process  through 
which  the  slag  is  passed  is  that  of  grinding.  This  must  be  thoroughly  done, 
for  it  is  found  that  the  availability  of  the  phosphorus  depends  very  largely  upon 
the  fineness  of  subdivision.  A  sample  should  contain  at  least  80  or  90  per  cent 
of  powder  which  passes  through  a  sieve  of  100  meshes  to  the  linear  inch,  i.e. 
10,000  to  the  square  inch.  Thomas  phosphate  has  given  excellent  results, 
especially  in  soil  somewhat  deficient  in  lime  and  rich  in  organic  matter." 

The  total  quantity  of  basic  slag  phosphate  now  used  in  Europe 
as  a  phosphorus  fertilizer  amounts  to  several  million  tons  a  year. 

Ground  natural  rock  phosphate  has  not  been  put  to  direct  use 
as  a  fertilizer  to  any  large  extent,  but  the  subject  merits  and  re- 
ceives a  thorough  consideration  in  the  following  pages.  Numerous 
trials  both  in  Europe  and  America  extending  over  only  one  or 
two  years,  without  addition  of  organic  matter,  and  in  direct  com- 
parison with  acid  phosphate  or  bone  meal  containing  an  amount 
of  phosphorus  equal  to  the  total  amount  in  the  raw  phosphate 
used,  have  not,  as  a  rule,  given  satisfactory  results,  and  in  conse- 
quence the  direct  use  of  this  material  has  been  discouraged  by 
some  investigators,  and  the  Association  of  German  Agricultural 
Experiment  Stations  has  even  passed  formal  resolutions  discourag- 
ing the  general  use  of  nonacidulated  rock  phosphate  (Landwirt- 
schaftlichen  Versuchs-Stationen,  67,  329). 

The  mineral  phosphates  differ  from  bone,  in  that  they  lack  the 
organic  matter  in  porous  structure;  and  they  differ  from  slag  in 
that  they  are  not  mixed  or  combined  with  caustic  lime  capable  of 
slacking  and  disintegrating  into  extremely  small  particles.  The 
fact  is,  however,  that  wherever  fine-ground  natural  rock  phosphate 
has  been  used  liberally ;  that  is,  somewhat  in  proportion  to  equiva- 
lent values  in  comparison  with  acid  phosphate,  and  in  connection 
with  decaying  matter,  it  has  given  satisfactory  results,  even  during 
the  first  rotation,  and,  with  continued  use,  it  proves  to  be  the  most 
economical  and  profitable  form  of  phosphorus  to  use  in  the  adop- 
tion of  systems  of  permanent  agriculture. 

In  the  study  of  this  extremely  important  question  it  is  well  to 
keep  in  mind  some  broad  fundamental  facts.  Thus,  the  phos- 

1  Substituted  for  "phosphoric  acid,"  both  here  and  in  several  other  quotations 
from  different  writers.  —  C.  G.  H. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     241 

phorus  contained  in  the  soil  is  not  in  the  form  of  acid  phosphate, 
but  largely,  at  least,  in  the  form  of  pulverized  or  disintegrated 
rock;  and  yet  it  is  the  common  experience  that  this  phosphorus 
can  be  made  available  by  large  use  of  clover  and  other  green  ma- 
nures. It  is  an  interesting  and  absolute  fact,  too,  that  phosphatic 
marls,  containing  phosphorus  in  the  ordinary  insoluble  mineral 
form,  have  been  much  used  for  centuries  for  direct  application 
to  the  land.  It  is  recorded  by  writers  that,  when  the  Romans 
first  invaded  Britain,  "  the  natives  were  found  using  phosphatic 
marls  to  obtain  better  crops." 

The  United  States  Bureau  of  Soils  states  that  millions  of  tons  of 
the  greensand  marl  of  New  Jersey  have  been  used  "  as  a  natural 
fertilizer";  and,  according  to  the  Bureau's  analysis  of  a  specimen 
"  collected  as  a  sample  to  show  the  amount  of  plant  food  in  ma- 
terial actually  used  as  a  fertilizer,"  this  marl  contains  less  than 
i  per  cent  (18  pounds  per  ton)  of  acid-soluble  potassium,  and  but 
little  more  calcium  and  magnesium  than  could  be  combined  in 
the  phosphates  present.  Evidently,  the  fertilizing  value  of  the 
marl  is  due  very  largely  to  its  phosphorus  content,  which  amounts 
to  28.6  pounds  per  ton.  In  comparison  it  may  be  noted  that  one 
ton  of  the  most  common  corn-belt  soil  contains  about  1.2  pounds 
of  phosphorus,  8  pounds  of  acid-soluble  potassium,  and  35  pounds 
of  total  potassium;  and  that  200  pounds  (the  average  application) 
of  the  most  common  "  complete  "  commercial  fertilizer  contain 
about  8|-  pounds  of  total  phosphorus  and  3^  pounds  of  potassium. 

An  analysis  by  the  Bureau  of  Soils  of  the  greensand  marl  of 
Prince  George  County,  Maryland,  shows  about  J  pound  of  phos- 
phorus and  42.6  pounds  of  acid-soluble  potassium,  in  one  ton. 
The  following  statements  are  quoted  from  the  Report  of  the  Bureau 
of  Soils  for  1901,  pages  186-187: 

"It  is  probable  that  the  New  Jersey  greensand  marls  would,  on  the  average, 
have  a  phosphorus  content  fifty  times  as  great  as  the  corresponding  marls  from 
Maryland." 

"In  the  Prince  George  area  this  greensand  marl,  which  occurs  along  the 
numerous  stream  cuttings  and  natural  cliffs,  has  only  been  used  to  a  slight 
extent  as  a  source  of  fertilizer.  ...  In  other  areas,  both  in  the  United  States 
and  foreign  countries,  the  greensand  marl  has  long  been  utilized  as  an  inex- 
pensive though  effective  medium  for  restoring  impoverished  soils. " 


242        SYSTEMS   OF   PERMANENT  AGRICULTURE 

There  are  several  points  especially  favorable  to  the  use  of  natural 
rock  phosphate  where  proper  conditions  can  be  provided: 

The  first  is  the  fact  that  phosphorus  in  fine-ground  raw  phos- 
phate can  be  obtained,  delivered  to  the  heart  of  the  corn  belt,  for 
about  3  cents  a  pound,  or  for  $7.50  for  a  ton  of  phosphate  contain- 
ing 250  pounds  of  phosphorus,  or  perhaps  $9.00  for  a  ton  contain- 
ing 300  pounds  of  phosphorus;  while  phosphorus  will  cost  about 
10  cents  a  pound  in  steamed  bone  meal,  12  cents  a  pound  in  acid 
phosphate,  and  about  30  cents  a  pound  in  ordinary  so-called  com- 
plete fertilizers.  In  the  adoption  of  systems  of  permanent  agri- 
culture, one  can  easily  afford  to  apply  to  the  soil,  in  natural  phos- 
phate, larger  quantities  of  phosphorus  than  are  removed  in  the 
largest  crops,  and  thus  provide  a  truly  permanent  system  with 
respect  to  phosphorus. 

The  second  point  is  that  lower  grades  of  phosphate  can  be  used 
for  direct  application  to  the  soil  than  can  be  utilized  in  the  manu- 
facture of  acid  phosphate.  For  acid-phosphate  manufacture  the 
raw  material  must  be  not  only  high  in  phosphorus,  but  it  must  be 
low  in  certain  forms  of  impurities,  such  as  iron  and  aluminum 
compounds,  which,  if  present,  require  much  larger  use  of  sulfuric 
acid  and  also  make  an  unsatisfactory  product;  but  phosphates  of 
moderate  phosphorus  content  and  even  with  considerable  iron  and 
aluminum  present,  which  have  hitherto  been  left  on  the  dump  piles 
as  worthless,  are  now  being  used  for  direct  application  to  the  land 
in  connection  with  liberal  amounts  of  farm  manure  or  clover  or 
other  forms  of  decaying  organic  matter.  Other  low-grade  phos- 
phates are  being  mined  and  ground  for  direct  use.  If  12^  per 
cent  phosphate  (62^  per  cent  tricalcium  phosphate)  is  worth  $7.50 
per  ton,  then  10  per  cent  phosphate  (50  per  cent  pure)  is  worth 
$6.00  a  ton;  and  even  8  per  cent  phosphate  (160  pounds  of  phos- 
phorus per  ton)  is  worth  $4.80  a  ton,  which  would  allow  $2.00  a 
ton  for  the  fine-ground  phosphate  on  board  cars  in  bulk  at  the  mine, 
and  $2.80  for  freight,  the  average  rate  from  theTennessee  phosphate 
district  to  southern  Illinois  points.  The  possibility  of  using  these 
low-grade  phosphates,  of  which  there  are  immense  deposits,  is  of 
enormous  importance  in  the  general  adoption  of  permanent  sys- 
tems of  soil  improvement. 

A  third  point  in  favor  of  raw  phosphate,  in  common  with  bone 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     243 

and  slag,  is  that  it  is  free  from  acidity  and  has  no  tendency  to  injure 
the  soil.  This  is  a  minor  advantage,  because,  if  acidity  develops 
from  the  continued  use  of  acid  phosphate  (and  it  does),  it  can  be 
corrected  at  small  expense  by  the  addition  of  any  form  of  lime. 

Another  point,  previously  mentioned,  of  fundamental  signifi- 
cance is  the  simple  fact  that  a  form  of  phosphorus  originally 
present  in  all  natural  soil  material  is  finely  divided  natural  rock 
phosphate,  and  through  all  agricultural  history  the  principal 
source  of  phosphorus  in  plant  growth  has  been  this  same  natural 
phosphate.  On  most  normal  soils  one  of  the  chief  benefits  of  farm 
manure  and  green  manures  is  undoubtedly  due  to  their  power  to 
liberate  phosphorus  from  these  insoluble  natural  phosphates  of 
the  original  soil. 

In  considering  culture  experiments,  whether  field  cultures  or 
pot  cultures,  three  points  should  be  kept  in  mind : 

(1)  What  are  the  limiting  factors  of  plant  growth  under  the 
conditions  of  the  experiment? 

(2)  Does  the  applied  fertilizer  increase  the  crop  yield  by  direct 
or  indirect  action? 

(3)  In  case  of  insoluble  fertilizers,  are  the  conditions  such  that 
the  plant  food  applied  will  be  made  available  to  the  crop? 

Thus,  an  experiment  to  determine  the  comparative  agricultural 
value  of  different  forms  of  phosphorus  cannot  be  expected  to  fur- 
nish satisfactory  evidence  if  conducted  on  a  soil  in  which  nitrogen 
is  the  element  that  limits  the  crop  yield;  or,  even  though  phos- 
phorus is  the  first  limiting  element,  the  results  cannot  be  conclu- 
sive if  the  nitrogen  limit  is  but  little  higher.  For  example,  if  the 
conditions  are  such  that  the  soil  will  furnish  phosphorus  for  only 
40  bushels  of  corn  per  acre,  and  sufficient  nitrogen  for  only  45  bush- 
els per  acre,  the  yield  cannot  be  increased  above  45  bushels  by  the 
addition  of  phosphorus  alone,  no  matter  what  form  is  applied  or 
how  much  becomes  available.  In  other  words,  one  phosphate 
fertilizer  might  supply  phosphorus  for  only  5  bushels,  and  another 
sufficient  for  25  bushels,  increase,  but  the  results  of  the  culture 
experiment  would  show  no  such  difference,  because  beyond  the 
45  bushels  the  yield  is  limited  by  a  second  entirely  different  factor. 

The  second  point  is  important  with  every  form  of  experiment. 
Thus,  a  student  reported  having  found  silver  in  an  unknown  solu- 


244 

tion  because  the  addition  of  hydrochloric  acid  produced. a  white 
precipitate.  The  Professor  asked:  "How  do  you  know  that  this 
precipitate  is  not  due  to  lead  or  mercury?  "  and  the  student  replied, 
"  Because  I  was  not  testing  for  lead  or  mercury  at  all." 

Similarly  one  may  apply  wood  ashes  to  ascertain  if  the  soil  is 
deficient  in  potassium,  or  he  may  turn  under  a  spring  growth  of 
clover  to  ascertain  if  the  soil  needs  more  nitrogen,  and  from  the 
increased  yield  he  may  think  both  of  these  elements  are  deficient; 
but  in  the  one  case  the  increase  may  be  due,  not  to  the  potassium 
as  plant  food,  but  to  the  basic  or  alkaline  properties  of  the  lime 
and  other  carbonates  in  correcting  soil  acidity,  and  in  the  other 
case  not  to  the  nitrogen  supplied,  but  to  the  liberation  of  phos- 
phorus from  the  meager  supply  in  the  soil  by  the  action  of  decaying 
organic  matter. 

It  is  never  safe  to  assume  that  the  action  of  soluble  fertilizers, 
such  as  sodium  nitrate,  acid  phosphate,  kainit,  or  other  potassium 
salts,  is  due  entirely  to  the  respective  plant-food  elements  for  which 
those  materials  are  valued,  especially  when  heavy  applications 
are  made,  as  must  be  done  with  sodium  nitrate  and  kainit  if  suffi- 
cient nitrogen  and  potassium  are  thus  provided  to  meet  the  needs 
of  good  crops,  more  than  900  pounds  of  sodium  nitrate  and  700 
pounds  of  kainit  being  required  for  a  hundred-bushel  crop  of  corn. 

About  400  pounds  of  acid  phosphate  would  be  required  for  such 
a  crop,  and  this  would  contain  more  manufactured  land-plaster 
(calcium  sulfate)  than  monocalcium  phosphate,  as  will  be  seen  by 
computation  from  the  reaction  expressed  by  the  equation: 

Ca3(PO4)2  +  2H2SO4  =  CaH4(PO4)2  +  2CaSO4. 

Dried  blood  and  steamed  bone  meal  are  among  the  most  trust- 
worthy materials  for  culture  experiments  to  determine  if  the  soil 
is  in  need  of  nitrogen  or  phosphorus,  and  potassium  sulfate  is 
probably  the  least  objectionable  form  of  potassium,  although  solu- 
tions of  such  soluble  salts  have  some  power  to  liberate  phosphorus 
contained  in,  or  applied  to,  the  soil,  and  by  this  indirect  action  to 
bring  about  more  or  less  increase  in  crop  yields  not  due  to  potas- 
sium as  plant  food.  Steamed  bone  meal  contains  a  small  amount 
of  organic  nitrogen,  but  even  if  it  were  all  made  available,  the 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     245 

amount  in  200  pounds  would  be  sufficient  to  increase  the  yield  of 
corn  by  one  bushel,  while  such  an  application  would  contain  more 
phosphorus  than  a  hundred-bushel  crop  of  corn. 

In  Tables  37,  38,  and  39  are  recorded  in  detail  the  results  of 
the  world's  most  important  and  complete  investigation  thus  far 
reported  concerning  the  use  and  comparative  value  of  raw  rock 
phosphate.  These  experiments  were  begun  by  the  Ohio  Agricul- 
tural Experiment  Station  in  1897,  and  through  the  kindness  of 
Director  Thorne  the  author  is  able  to  include  twelve  years'  data  in 
these  tables. 

In  these  experiments  a  three-year  rotation  of  corn,  wheat,  and 
clover  has  been  followed  on  three  separate  tracts  of  land,  so  that 
every  crop  may  be  represented  every  year.  One  plot  in  each  series 
receives  8  tons  per  acre  of  manure  "taken  from  the  open  barn- 
yard, where  it  has  been  accumulating  during  the  winter,"  and 
applied  to  the  clover  sod  in  the  spring,  to  be  plowed  under  for  corn. 
Another  plot  receives  at  the  correct  time  8  tons  per  acre  of  manure 
"  taken  from  box  stalls,  where  it  has  accumulated  under  the  feet 
of  animals  kept  continuously  in  the  stalls." 

Two  other  plots  in  each  series  receive  the  same  kind  and  quantity 
of  manure  with  each  ton  of  which  40  pounds  of  fine-ground  raw 
rock  phosphate  have  been  mixed,  and  two  other  plots  receive  ma- 
nure with  each  ton  of  which  40  pounds  of  acid  phosphate  have 
been  mixed. 

Every  third  plot  in  each  tract  or  series  receives  no  manure  or 
other  fertilizer. 

In  the  tables  are  reported  the  yields  of  corn,  wheat,  and  clover, 
the  experiment  having  been  started  in  1897  on  section  A,  and  in 
1898  on  sections  B  and  C.  Clover  failed  the  first  three  years,  and 
in  its  place  soy  beans  were  grown,  and  they  were  plowed  under. 
The  hay  crop  harvested  in  1907  was  soy  beans,  grown  because  of 
clover  failure. 

Chemical  analysis  and  the  results  of  other  field  experiments 
show  that  the  Wooster  soil  is  most  deficient  in  phosphorus,  with 
nitrogen  as  the  second  limiting  element. 

In  considering  the  data  given  in  Tables  37,  38,  and  39,  it  should 
be  kept  in  mind  that  each  table  gives  results  that  are  complete 
and  entirely  independent.  Thus,  by  using  three  different  tracts 


246       SYSTEMS   OF   PERMANENT   AGRICULTURE 

of  land,  the  experiment  was  conducted  in  triplicate;  and  even 
each  of  the  triplicate  tests  was  in  a  sense  duplicated  in  that  a  double 
comparison  is  made  between  the  two  forms  of  phosphorus,  the  test 
with  yard  manure  being  entirely  independent  of  the  test  with  stall 
manure. 

For  convenience  the  average  yield  of  each  crop  is  given  by  plots 
for  each  series  of  plots  separately.  Thus,  as  an  average  of  four  corn 
crops  in  Series  A,  plot  15  with  yard  manure  alone  produced  41.5 
bushels,  and  plot  2  with  yard  manure  and  raw  phosphate  produced 
54.9  bushels,  showing  by  direct  comparison  a  gain  of  13.5  bushels 
due  to  the  raw  phosphate.  Further  comparison  shows  average 
gains  of  2.1  bushels  of  wheat  and  .58  ton  of  clover  hay  by  raw 
phosphate  and  yard  manure  above  the  yields  made  where  un- 
treated manure  was  used. 

A  similar  comparison  shows  average  gains  of  5  bushels  of  corn, 
3.9  bushels  of  wheat,  and  .37  ton  of  hay  by  raw  phosphate  and  stall 
manure  above  the  yields  where  stall  manure  alone  was  used. 
Acid  phosphate  also  produced  marked  gains,  the  average  gross 
increase  being  somewhat  greater  than  with  the  raw  phosphate, 
but  the  net  profit  being  slightly  less  on  Series  A. 

Attention  is  called  to  the  fact  that  8  tons  of  manure  per  acre 
have  been  applied  every  three  years  to  all  manured  plots.  This 
does  not  do  full  justice  to  the  phosphate  plots,  because  these  plots 
have  yielded  as  an  average  about  one  fourth  more  produce  than 
the  plots  receiving  manure  alone,  and  from  this  increased  produce 
about  one  fourth  more  manure  can  be  made  in  regular  farm  prac- 
tice. Consequently,  after  the  first  rotation,  the  applications  of 
manure  should  be  larger  on  the  phosphate  plots  in  proportion  to 
the  produce  of  the  previous  rotation;  whereas,  to  apply  equal 
amounts  of  manure  to  plot  15  and  plot  2,  for  example,  means 
essentially  that  some  of  the  produce  from  plot  2  is  used  to  make 
part  of  the  manure  that  is  applied  to  plot  15. 

In  the  above  comparison  to  determine  the  effect  of  the  phos- 
phorus used,  the  yields  with  manure  alone  are  subtracted  directly 
from  the  yields  with  manure  and  phosphorus.  As  an  average  of 
many  tests,  this  direct  method  of  comparison  is  perhaps  as  good  as 
any  indirect  method,  but  where  a  small  number  of  tests  on  only  a 
few  fields  are  to  be  considered,  probably  an  indirect  method  of 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS    247 


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SOIL  TREATMENT  . 

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1899  Wheat,  bu. 
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250        SYSTEMS    OF   PERMANENT  AGRICULTURE 

comparison,  will,  as  a  rule,  give  more  trustworthy  results.  Thus, 
we  may  subtract  the  average  yields  of  the  adjoining  untreated 
plots,  14  and  17,  from  the  yields  of  the  manured  plots,  15  and  16, 
to  determine  the  increase  produced  by  manure  alone.  Then  we 
may  subtract  the  yield  either  of  plot  4  or  the  average  yield  of  the 
three  untreated  plots,  i,  4,  and  7,  from  the  yields  of  the  plots 
which  receive  both  manure  and  phosphorus,  to  determine  the  in- 
crease produced  by  manure  and  phosphorus  combined,  subtract- 
ing from  these  figures  the  increases  for  manure  alone,  to  determine 
the  effect  of  phosphorus.  Still  another  method  would  be  to  average 
all  of  the  untreated  plots  whose  results  are  in  satisfactory  agree- 
ment, and  discard  the  results  of  those  that  differ  so  widely  as  to 
be  clearly  abnormal.  By  this  method  probably  the  results  from 
plots  Ai,  67,  and  Ci  would  be  discarded. 

By  any  of  these  methods  of  comparison,  direct  or  indirect,  it 
will  be  found  that,  as  a  general  average  of  all  tests  on  all  series,  the 
raw  phosphate  has  produced  practically  the  same  gross  increase 
as  the  acid  phosphate,  although  the  acid  phosphate  applied  cost 
twice  as  much  as  the  raw  phosphate. 

Yet  another  indirect  method  of  comparison  can  be  made  and 
this  one  is  preferred  by  the  Ohio  Experiment  Station.  This  method 
assumes  that  naturally  the  land  varies  somewhat  uniformly  from 
one  untreated  plot  to  the  next  untreated  plot,  so  that  plot  15,  for 
example,  if  it  had  remained  unmanured,  would  have  produced  a 
yield  equal  to  the  sum  of  two  thirds  of  the  yield  of  plot  14  plus 
one  third  of  the  yield  of  plot  17,  and  that  this  computed  yield  for 
plot  15  (untreated),  subtracted  from  the  actual  yield  of  plot  15, 
gives  the  increase  produced  by  the  manure.  The  effect  of  the  ma- 
nure and  phosphate  is  computed  in  the  same  manner,  and  the 
difference  gives  the  effect  of  the  phosphorus. 

This  method  would  be  correct  if  the  assumption  upon  which  it  is 
based  were  correct;  but  considering  that  the  change  in  the  direc- 
tion of  such  a  curve  is  just  as  likely  to  occur  on  any  other  plot  as 
on  the  plots  that  happen  to  be  numbered  i,  3,  4,  7,  etc.,  its  appli- 
cation may  be  of  questionable  value.  However,  in  Tables  37, 
38,  and  39,  the  actual  yields  are  reported  for  the  twelve  years, 
and  from  these  any  one  can  make  his  own  deductions. 

The  total  value  of  the  three  crops,  based  upon  the  average  yields, 


USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     251 

is  given  for  each  series,  counting  35  cents  a  bushel  for  corn,  70 
cents  for  wheat,  and  $6.00  a  ton  for  hay.  These  prices  1  are  based 
upon  the  ten-year  average  farm  price  for  Illinois  as  reported  by  the 
United  States  Department  of  Agriculture  for  the  years  1899  to 
1908,  for  which  the  reported  averages  are  40.1  cents  a  bushel  for 
corn,  76.5  cents  for  wheat,  and  $9.32  a  ton  for  marketable  hay. 
The  differences  between  these  averages  and  the  prices  used  in  the 
tables  will  probably  cover  the  cost  of  husking  corn  and  threshing 
wheat,  stacking  and  baling  the  hay,  and  marketing  the  increase. 
The  value  of  the  increase  in  corn  stover  and  wheat  straw  may  per- 
haps cover  the  extra  cost  of  handling  (binding  twine,  etc.)  and 
occasional  losses  for  poor  quality  of  grain  and  hay.  The  prices 
used  are  intended  to  be  sufficiently  conservative  to  guard  against 
financial  exaggeration.  Other  prices  should  be  used  to  suit  local 
conditions. 

The  special  purpose  of  reducing  all  results  to  the  basis  of  value 
is  to  make  possible  a  more  simple  comparison.  From  these  total 
values  of  the  three  crops  by  plots,  the  gain  for  treatment  is  computed 
by  the  Ohio  method,  except  that  in  Series  C  the  results  from  plot  i 
are  discarded 2  as  being  plainly  abnormal  and  untrustworthy. 
A  comparison  of  the  value  of  crops  grown  on  plots  A2,  A3,  and  A5, 
on  plots  B2,  63,  and  65,  and  on  plots  C2,  €3,  and  €5,  plainly 
indicates  that  plot  C2  is  normal;  and  the  effect  of  manure  and 
phosphorus  on  plots  C2  and  03  is  determined  by  subtracting  the 
average  results  of  plots  C4  and  07. 

It.  will  be  noted  that  the  cost  of  raw  phosphate  is  reckoned  at 
$7.50  per  ton  and  the  cost  of  acid  phosphate  at  $15  per  ton,  or 
$1.20  for  320  pounds  of  raw  phosphate  and  $2.40  for  320  pounds 
of  acid  phosphate,  applied  with  the  8  tons  of  manure  every  three 
years. 

Three  important  facts  are  clearly  established  by  these  data: 
(i)  the  value  of  manure,  (2)  the  superiority  of  stall  manure  over 

1  Elsewhere  the  author  uses  30  cents  a  bushel  for  oats,  the  lo-year  average  price 
for  Illinois  being  32.2  cents;  40  cents  a  bushel  for  barley,  44.7  cents  being  the 
lo-year  average  price  for  Minnesota  and  Wisconsin,  leading  barley  states;  and  50 
cents  a  bushel  for  potatoes,  the  New  York  ro-year  average  farm  price  being  57.6 
cents. 

2  A  personal  communication  from  Director  Thorne  states  that  this  plot  occupies 
a  depression,  running  lengthwise  of  the  plot,  with  higher  land  on  each  side.  Evi- 


252 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


yard  manure,  and  (3)  the  value  of  phosphorus  when  applied  in 
connection  with  manure.  The  first  two  will  be  further  discussed 
under  the  subject  of  farm  manure. 

As  an  average  of  the  results  from  the  three  series  of  plots,  the 
value  of  the  increase  from  320  pounds  of  raw  phosphate  was  $10.19 
with  yard  manure  and  $10.23  with  stall  manure;  and  the  value  of 
the  increase  from  320  pounds  of  acid  phosphate  was  $11.77  w^h 
yard  manure  and  $12.01  with  stall  manure,  the  value  of  the  ma- 
nure alone  having  been  deducted  in  all  cases.  If  we  subtract  from 
these  gross  gains  the  cost  of  the  phosphorus,  we  have  average  net 
profits  of  $9.01  for  raw  phosphate  and  $9.49  for  acid  phosphate; 
or,  on  the  basis  of  money  invested,  we  have  net  profits  of  751  per 
cent  from  raw  phosphate  and  395  per  cent  from  acid  phosphate. 

With  double' the  investment  the  profit  per  acre  is  slightly  greater 
from  acid  phosphate;  but,  on  the  basis  of  money  invested,  the  profit 
from  raw  phosphate  is  almost  double  that  from  acid  phosphate. 

dently  more  or  less  surface  wash  has  accumulated  in  this  depression  in  times  past. 
(See  the  accompanying  contour  map  of  this  Ohio  field.) 


SECTION  A 


NORTH 
SECTION  B 


SECTION  C 


7     8    9    10 


.    11    12  13  14  15  16  17  18   19  20      11    12 


15   16  17  18  19  20 


TOPOGRAPHY  OF  LAND  :   OHIO  EXPERIMENT 
One-foot  contour  lines;  highest  land  at  south  end  of  section  C. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     253 

The  student  or  landowner  must  draw  his  own  conclusions  as  to 
which  is  the  better  basis  upon  which  to  compute  the  profit.  It 
should  be  kept  in  mind  that  320  pounds  of  raw  phosphate  contains 
40  pounds  of  phosphorus,  while  320  pounds  of  acid  phosphate  con- 
tains about  20  pounds  of  that  element,  so  that  the  raw  phosphate 
is  enriching  the  soil  in  phosphorus  twice  as  much  as  the  acid  phos- 
phate, while  the  removal  in  crops  is  practically  equal. 

An  examination  of  the  values  of  the  three  crops  by  plots  suggests 
that  the  use  of  the  data  from  plot  Ai  ($25.02)  is  unfavorable  to 
the  raw  phosphate  on  that  series,  because  of  the  lower  uniform 
values  from  plot  A4  ($20.61)  and  plot  Ay  ($20.03).  ,On  tne  other 
hand,  the  use  of  the  data  from  plot  By  is  favorable  to  the  acid 
phosphate,  by  the  Ohio  method  of  comparison. 

By  the  method  of  direct  comparison,  by  which  the  total  values 
from  plots  15  and  16  (manure  alone)  are  subtracted  from  the  total 
values  from  plots  2  and  3  and  from  plots  5  and  6,  respectively,  it 
will  be  seen  that  the  average  value  of  the  increase  is  $10.59  from 
320  pounds  of  raw  phosphate,  and  $10.61  from  320  pounds  of  acid 
phosphate,  the  net  profit  per  acre  being  $9.39  for  the  raw  phosphate 
and  $8.21  for  the  acid  phosphate;  or,  on  the  basis  of  money  in- 
vested, the  net  profit  is  783  per  cent  for  raw  phosphate  and  342 
per  cent  for  acid  phosphate.  For  convenient  reference,  the  aver- 
age actual  yields  and  values  are  summarized  in  the  accompanying 
tabular  statement. 

TABLE  396.   OHIO  EXPERIMENTS  WITH  MANURE,  RAW  ROCK  PHOSPHATE, 

AND  ACID  PHOSPHATE 
Average  of  Twelve  Years,  with  Duplicate  Tests  on  Each  Field 


SOIL  TREATMENT 

FIELD 

A 

FIELD 

B 

FIELD 

C 

AVERAGE 

CORN,  BUSHELS  PER  ACRE 


Manure  alone  

47.2 

6r6 

C7.2 

^4.7 

Manure  and  rock  phosphate  

^6.4 

60.  C 

<C8.2 

61.4 

Manure  and  acid  phosphate  

=J4.6 

70.8 

62.0 

6?.i 

WHEAT,  BUSHELS  PER  ACRE 


Manure  alone      

20.  4 

21.7 

17.2 

19.8 

Manure  and  rock  phosphate  

27.4 

3O.4 

24.6 

26.1 

Manure  and  acid  phosphate  

23.8 

20.4 

2^.1 

26.1 

TABLE  396.  OHIO  EXPERIMENTS  WITH  MANURE,  RAW  ROCK  PHOSPHATE, 
AND  ACID  PHOSPHATE  —  Continued 


SOIL  TREATMENT 

FIELD 

A 

FIELD 

B 

FIELD 

c 

AVERAGE 

CLOVER  HAY,  TONS  PER  ACRE 


Manure  alone                          

1.  00 

1.34 

87 

I  3O 

Manure  and  rock  phosphate  

2.47 

I.  no 

I  7Q 

2  (X 

Manure  and  acid  phosphate  

2.21. 

1.76 

1.  02 

I.Q7 

TOTAL  VALUE  OF  THE  THREE  CROPS  PER  ACRE 


Manure  alone                     

$42.60 

$4^  47 

$?r  6c; 

$41  27 

Manure  and  rock  phosphate       .... 
Manure  and  acid  phosphate  

50.86 

4Q.I2 

56.42 
^.76 

48.30 

^0.76 

51.86 

51.88 

Cost  of  rock  phosphate  for  the  three  crops $1.20 

Cost  of  acid  phosphate  for  the  three  crops 2.40 


It  is  worth  while  to  note  that  the  first  corn  crop  on  Series  C 
(Table  39)  was  not  benefited  by  raw  phosphate,  and  the  first  corn 
crop  on  Series  B  (Table  38)  was  increased  only  2.7  bushels,  as  an 
average,  by  raw  phosphate,  while  other  instances  appear  in  which 
phosphorus  produced  no  apparent  benefit,  as,  for  example,  with 
stall  manure  for  corn  in  1901  and  1906,  and  with  either  manure 
for  wheat  in  1907,  all  of  which  emphasizes  the  fact  that  one  field 
trial  with  one  crop  for  one  year  may  have  almost  no  value  in  de- 
termining the  effect  of  additions  of  phosphorus  to  the  soil. 

Director  Thorne  has  expressed  some  disappointment l  because 

1  Considering  its  source,  the  following  statement  by  Director  Thorne,  taken  by 
itself,  probably  constitutes  the  strongest  "evidence"  that  can  be  quoted  in  favor 
of  acid  phosphate  and  against  the  use  of  raw  rock  phosphate.  In  referring  to  the 
general  averages  of  all  results  secured  in  these  manure-phosphate  experiments 
from  1897  to  I9°7»  he  says  (Ohio  Agricultural  Experiment  Station  Circular  83, 
page  23) : 

"While  the  treatment  of  manure  has  in  every  case  increased  its  effectiveness,  the 
gain  per  acre  produced  by  reenforcing  the  manure  with  acid  phosphate  has  been  so 
much  greater  than  that  from  any  other  treatment  that  it  has  not  been  profitable 
to  use  anything  else,  even  though  the  other  materials  had  cost  nothing. " 

Of  course,  in  this  statement,  Director  Thorne  refers  not  to  profit  on  investment, 
but  to  profit  per  acre  regardless  of  the  amount  invested,  and  he  includes  the  data 


CHARLES  E.  THORNE,  DIRECTOR  OF  OHIO 
AGRICULTURAL  EXPERIMENT  STATION 


USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     255 

the  40  pounds  of  phosphorus  applied  in  raw  phosphate  has  not  pro- 
duced markedly  greater  benefit  than  the  20  pounds  in  acid  phos- 
phate, these  applications  having  been  repeated  in  connection  with 
manure  every  three  years  for  twelve  years.  This  is  an  important 
and  interesting  question.  It  may  be  best  considered  in  connection 
with  the  general  average  yields  recorded  in  Table  40,  which,  it  may 
be  observed,  includes  results  from  the  use  of  kainit,  gypsum,  and 
"  complete  "  fertilizers.  The  amounts  of  kainit  and  gypsum  used 
are  the  same  as  raw  phosphate  and  acid  phosphate;  namely,  320 
pounds  with  8  tons  of  manure  per  acre  every  three  years.  The  kainit 
costs  about  $15  per  ton  and  the  gypsum  about  $6  per  ton.  The 
footnotes  to  Table  40  give  further  data,  so  that  any  one  may  make 
his  own  computations  concerning  the  increase  in  yield  or  profit 
from  every  kind  of  treatment.  (See  also  page  299.) 

Attention  is  called  to  the  fact  that  plot  n  is  a  continuation  of 
plot  i,  and  on  Series  C  it  is  so  abnormal  that  its  influence  is  seen 
in  the  general  average  of  every  crop. 

By  computations  from  Tables  23  and  40  it  is  a  simple  matter 
to  construct  most  of  Table  41,  in  which  a  balance  is  shown  for  the 
elements  nitrogen  and  phosphorus  supplied  and  removed  in  these 
experiments  with  manure  and  phosphates. 

The  figures  given  in  Table  41  may  be  considered  as  approxi- 
mately correct,  but  the  amounts  of  nitrogen  furnished  by  the  soil 
and  by  the  clover  residues  are  roughly  estimated.  This  estimate 
is  based  upon  the  assumption  that  the  total  clover  tops,  aside  from 
the  clover  hay  harvested,  will  be  equivalent  to  one  half  of  the  regu- 
lar hay  crop.  These  residues  consist  of  (i)  the  first  season's  growth, 
chiefly  after  the  wheat  harvest;  (2)  the  fall  growth  the  second 
season ;  and  (3)  the  following  spring  growth  before  plowing  for 
corn.  These  estimates  are  added  to  Table  41,  not  as  well-established 
facts,  but  rather  as  suggesting  methods  of  study  that  deserve 
further  investigation.  To  one  familiar  with  field  conditions  it 
seems  certain  that  the  clover  is  given  at  least  all  credit  due  for 

from  plot  Ci  in  computing  the  increase  produced  by  the  raw  phosphate  by  the 
Ohio  method  of  comparison.  As  a  suitable  topic  for  a  debating  society,  the  author 
suggests  the  question: 

Shall  we  use  acid  phosphate  or  raw  rock  phosphate  in  systems  of  permanent 
agriculture?  (See  page  299  for  later  average  results.) 


256       SYSTEMS   OF  PERMANENT  AGRICULTURE 


TABLE  40.   CROP  YIELDS  PER  ACRE  IN  OHIO  EXPERIMENTS  WITH  MANURE, 
PHOSPHATES,  KAINIT,  GYPSUM,  AND  "COMPLETE"  FERTILIZERS 

Average  of  Three  Series 


PLOT1 

No. 

TREATMENT  APPLIED 

CORN, 
12  YEARS 

WHEAT, 
it  YEARS 

HAY,  8 
YEARS 
(Tons) 

Grain 
(Bu.) 

Stover 
(Tons) 

Grain 
(Bu.) 

Straw 
(Tons) 

I 
2 

3 

4 

5 
6 

7 
8 
9 
10 

None     

37-2 

59-4 
63-3 

31.0 

60.3 
64.4 

30.8 

54-6 
60.  i 

32-9 

I.  II 

1.66 

I.78 

1.00 

1.64 

1.74 

•99 

1.58 
i-75 

I.OO 

12.  1 

25.0 
26.4 

IO.4 

25-3 
26.2 

9-7 
21.3 
23-4 

10.3 

•74 

1-35 
1.44 

.61 

1.36 
1.44 

•58 
1.  2O 

i-35 
.60 

I.I9 

1.90 
2.19 

.89 

1.77 
2.17 

•85 

1.49 
1.94 

•95 

Yard  manure  and  raw  phosphate   .     . 
Stall  manure  and  raw  phosphate    .     . 

None     

Yard  Manure  and  Acid  phosphate     . 
Stall  manure  and  acid  phosphate   .     . 

None     

Yard  manure  and  kainit   

Stall  manure  and  kainit    

None     

ii 

12 
J3 

14 

15 

16 

i7 

18 
J9 

20 

None     

36.8 

58.0 
60.7 

31.6 

51-2 
58.2 

36.6 

43-i 
44-4 

34-1 

1.17 

1.68 

1.78 

I.  CO 

1.44 

1.65 
1-15 

1.29 

1.23 

I.OI 

I3-1 

23-4 
23-3 

9.9 

18.8 
20.4 

IO.2 

13-4 
14.9 

IO.O 

.81 

1.32 
I-3I 

•57 

i.  06 
1.14 

.62 

.78 
.88 

.62 

1.30 

1.63 
1.65 

•85 

1.28 
1.63 

I.OO 

1.36 
i-43 

I.IO 

Yard  manure  and  gypsum     .... 
Stall  manure  and  gypsum      .... 

None     

Yard  manure  alone  

Stall  manure  alone  

None     

"Complete"  fertilizer2      

"Complete"  fertilizer3      

None     

1  In  the  field,  plots  i  and  n,  2  and  12,  etc.,  lie  end-to-end,  plot  n  being  essen- 
tially a  continuation  of  plot  i,  etc. 

2  The  "complete"  fertilizer  applied  to  plot   18,  every  three  years,  contains  160 
pounds  sodium  nitrate,   80  pounds  acid  phosphate,   and  80  pounds  potassium 
chlorid. 

*  The  "complete"  fertilizer  applied  to  plot  19,  every  three  years,  consists  of  100 
pounds  of  slaughter-house  tankage  (containing  6  pounds  of  nitrogen  and  6  pounds 
of  phosphorus),  80  pounds  of  acid  phosphate,  and  10  pounds  of  potassium  chlorid. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS 


257 


TABLE  41.   BALANCE  SHEET  FOR  NITROGEN  AND  PHOSPHORUS  IN  MANURE- 
PHOSPHATE  EXPERIMENTS 
Totals  for  Three  Years,  Pounds  per  Acre:    in  Part  roughly  Estimated 


Plot  No  

3 

3 

5 

6 

TREATMENT  APPLIED 

YARD 
MANURE, 
RAW 
PHOS- 
PHATE 

STALL 
MANURE, 
RAW 
PHOS- 
PHATE 

YARD 
MANURE, 
ACID 
PHOS- 
PHATE 

STALL 
MANURE, 
ACID 
PHOS- 
PHATE 

Nitrogen  removed  in  three  crops  
Nitrogen  supplied  in  manure    

211 
80 

232 

80 

207 
80 

23I 
80 

Nitrogen  difference     . 

1  3.1 

I"?2 

127 

1^1 

Nitrogen  in  clover  hay    

76 

88 

71 

87 

Nitrogen  from  soil  and  clover  residues  .     .     . 
Nitrogen  from  clover  residues  (estimated)  .     .   • 

55 
38 

64 

44 

56 
36 

64 
44 

Nitrogen  furnished  by  soil  (estimated)  .     .     . 

i7 

20 

20 

20 

Phosphorus  removed  in  three  crops  .... 
Phosphorus  supplied  in  manure  and  phosphate 

31 
64 

34 
56 

31 
44 

34 
36 

Phosphorus  added  in  excess     

•2-1 

22 

12 

2 

nitrogen  fixation.  In  other  words,  that  the  draft  upon  the  soil 
by  the  crops  grown  is  likely  to  be  greater  rather  than  less  than  20 
pounds  above  that  supplied  by  the  manure  and  clover,  and,  in 
addition  to  this,  there  are  losses  of  nitrogen  in  drainage  waters 
probably  exceeding  all  other  additions  (as  in  rainwater,  by  azo- 
tobacter,  etc.).  The  loss  of  nitrogen  by  drainage  is  no  doubt 
much  greater  from  the  best-treated  plots  than  from  the  untreated 
plots.  Failing  nitrogen  may  finally  reduce  the  phosphorus  effect. 
On  the  whole,  it  seems  clear  that  nitrogen  must  limit  the  crop 
yields  on  these  four  plots  treated  with  manure  and  phosphate. 
On  the  other  hand,  in  every  case  the  phosphorus  applied  exceeds 
the  amount  removed  in  the  crops,  so  that,  instead  of  there  being 
any  draft  upon  the  soil,  there  is  a  positive  increase  in  the  phosphorus 
content  of  the  soil  above  the  crop  requirements.  This  increase 
varies  from  2  and  13  pounds  with  acid  phosphate  to  22  and  33 
pounds  with  raw  phosphate.  If  nitrogen  is  the  limiting  element  on 
all  of  these  manure-phosphate  plots,  it  is  plain  to  see  why  the  raw 
phosphate  gives  practically  no  larger  yields  than  the  acid  phos- 


258        SYSTEMS   OF   PERMANENT  AGRICULTURE 

phate,  even  though  twice  as  much  phosphorus  is  applied  in  the  raw 
phosphate  as  in  the  acid  phosphate.  If  more  clover  were  plowed 
under  or  if  more  manure  were  returned,  so  as  to  remove  the  nitro- 
gen limit,  the  comparative  value  of  the  two  forms  of  phosphorus 
could,  perhaps,  be  more  definitely  determined.  Such  additional 
supplies  of  decaying  organic  matter  would  tend  to  make  avail- 
able still  larger  supplies  of  potassium,  magnesium,  etc.,  and  thus 
to  avoid  their  becoming  limiting  factors.  It  is  possible  that  the 
use  of  acid  phosphate  tends  to  prevent  loss  of  ammonia  from  the 
manure  during  the  few  weeks  that  elapse  between  the  mixing  of 
the  phosphate  with  manure  and  the  application  to  the  land. 

Two  important  facts  are  well  established  by  these  Ohio  experi- 
ments: First,  that  fine-ground  natural  rock  phosphate  is  a  material 
that  can  be  employed  with  very  large  profit  as  a  phosphorus 
fertilizer,  when  used  in  connection  with  liberal  amounts  of  decaying 
organic  matter;  and,  second,  that,  under  the  conditions  of  these 
experiments,  the  raw  phosphate  gave  practically  the  same  profit 
per  acre,  and  twice  as  much  profit  for  the  money  invested,  as  the 
acid  phosphate.  (For  later  averages,  see  page  299.) 

In  the  Ohio  Farmer  for  August  22,  1908,  Director  Thome  re- 
ports some  interesting  and  valuable  results  showing  the  effect  of 
raw  phosphate  on  clover  grown  in  1908  on  the  Strongsville  Experi- 
ment Farm,  located  between  Wooster  and  Cleveland,  on  a  heavier 
type  of  soil  of  nearly  level  topography.  The  author  has  also  been 
given  the  figures  for  the  1908  oat  crop. 

Director  Thorne  states  that  lime  and  raw  phosphate  were  ap- 
plied across  the  plots  in  the  five-year  rotation,  "  dividing  the  sec- 
tion of  plots  into  4  divisions,  using  one  ton  of  lime  per  acre  on  the 
first,  two  tons  of  lime  on  the  second,  one  ton  of  floats  on  the  third, 
and  two  tons  of  floats  on  the  fourth,  applying  the  lime  and  floats 
across  all  the  plots,  fertilized  and  unfertilized  alike." 

The  crops  grown  in  the  five-year  rotation  experiments  at  Strongs- 
ville are  corn,  oats,  wheat,  clover,  and  timothy,  and  the  fertilizers 
applied  are  similar  to  those  in  the  older  five-year  rotation  at  Woos- 
ter as  reported  in  Table  82,  with  ten  additional  plots  in  each  series. 
It  is  understood  that  during  the  course  of  five  years  all  of  the  series 
have  received  (or  will  receive)  the  treatment  with  lime  and  raw 
phosphate,  as  above  described. 


USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     259 

The  data  thus  far  reported  concern  only  the  clover  and  oats  for 
1908,  and  they  almost  certainly  show  more  marked  differences  than 
will  appear  from  long-continued  and  more  general  experiments : 

OHIO  EXPERIMENTS  WITH  LIME  AND  RAW  PHOSPHATE 


SPECIAL  SOIL  TREATMENT  APPLIED,  TONS  PEE  ACRE 

YIELDS,  PER  ACRE,  1908 

Clover  Hay  (Lb.) 

Oats  (Bu.) 

(a)  Average  of  14  Otherwise  Unfertilized  Plots 


One  ton  of  lime  

2220 

-12  7 

Two  tons  of  lime     

2670 

->e  7 

One  ton  of  raw  phosphate     

CO4O 

47  8 

Two  tons  of  raw  phosphate  

CIQO 

ec  o 

(b)  Average  of  26  Otherwise  Fertilized  Plots 


One  ton  of  lime  

3  7oo 

43.8 

Two  tons  of  lime     

1880 

4.C.Q 

One  ton  of  raw  phosphate     

£460 

<2  7 

Two  tons  of  raw  phosphate    

C7CQ 

62.2 

Even  if  we  assume  that  the  lime  produced  no  increase,  the  effect 
of  the  raw  phosphate  is  very  marked.  On  the  "  otherwise  unfer- 
tilized "  land  one  ton  of  raw  phosphate  per  acre  produced  1.41 
tons  more  clover  and  15.1  bushels  more  oats,  the  value  of  which, 
at  $6  per  ton  and  30  cents  a  bushel,  respectively,  would  amount 
to  $12.99,  or  enough  to  pay  for  two  tons  of  ra\v  phosphate  at  $3.50 
per  ton  where  the  freight  rate  does  not  exceed  $3  (as  in  southern 
Illinois). 

The  two-ton  application  produced  markedly  greater  effect  on  the 
oats,  but  not  on  the  clover.  These  results  include  two  entirely 
separate  series  of  plots,  and  each  reported  yield  is  the  average  from 
a  large  number  of  plots.  The  data  must  not  be  considered  as  ex- 
ceedingly trustworthy,  but  we  must  agree  with  Director  Thome's 
statement  that  "  it  looks  as  though  we  were  getting  something 
worth  while  there."  Knowing  that  the  effect  of  lime  where  needed 


260       SYSTEMS   OF   PERMANENT   AGRICULTURE 

is  usually  marked  on  both  clover  and  oats,  the  "  increase  "  given 
for  phosphate  must  be  regarded  as  quite  unusual.  Not  more  than 
one  tenth  of  the  phosphorus  applied  would  be  removed  in  the  two 
crops.  These  results  point  toward  the  possibility  of  adopting 
profitable  systems  of  permanent  agriculture;  and  yet  the  most 
common  fertilizer  practice  among  the  farmers  of  Ohio  is  to  apply 
about  7  pounds  of  soluble  phosphorus  per  acre,  with  3  or  4  pounds 
each  of  nitrogen  and  potassium,  in  200  pounds  of  "complete" 
fertilizer  about  twice  during  a  four-year  or  five-year  rotation. 

In  the  Rural  New  Yorker  for  June  5,  1909,  Director  Thorne 
reports  an  average  yield  of  2440  pounds  of  clover  hay  with  lime 
applied,  and  5112  pounds  where  rock  phosphate  is  used,  with  no 
other  fertilizers;  and  where  nitrogen  or  potassium  had  been  applied, 
the  yield  with  lime  was  2606  pounds  and  with  rock  phosphate, 
5488  pounds,  although  where  lime  and  a  "  complete  "  fertilizer, 
including  nitrogen,  potassium,  and  480  pounds  of  acid  phosphate, 
were  used,  the  total  yield  of  clover  hay  was  only  4259  pounds. 
The  following  comment  is  made  by  Thorne: 

"This  experiment  thus  indicates  that  floats  (raw  phosphate)  may  be  very 
usefully  employed  for  the  combined  purpose  of  carrying  lime  and  phosphorus, 
the  increase  over  the  limed  land  being  more  than  enough  in  this  one  crop  to 
pay  for  one  ton  of  floats  per  acre,  which  quantity  has  seemed  to  be  as  effective  as 
the  larger  quantity,  although  the  two  tons  of  lime  have  produced  a  larger 
yield  than  the  one  ton,  though  not  enough  larger  to  pay  the  additional  cost. 
This  experiment,  therefore,  is  confirming  those  of  the  Maryland  and  Illinois 
stations  in  showing  that  floats  may  be  profitably  used  as  a  carrier  of  phos- 
phorus on  acid  soils  well  stocked  with  organic  matter,  but  the  meager  effect 
produced  upon  cereal  crops  preceding  clover  would  call  for  caution  in  de- 
pending upon  floats  alone. " 

Of  course,  more  clover  means  more  humus  and  more  nitrogen 
if  the  clover  is  plowed  under  either  directly  or  in  manure;  and, 
while  the  cereal  crops  preceding  clover  are  quite  certain  to  be  un- 
satisfactory, they  are  sure  to  be  increased  after  plowing  under  the 
larger  amount  of  clover  or  manure  with  phosphate.  The  data 
reported  by  Thorne  in  these  experiments  do  not  show  what  increase 
was  produced  by  lime  alone,  all  plots  having  been  treated  either 
with  lime  or  with  raw  phosphate,  and  consequently  there  seems 
to  be  no  support  for  the  suggestion  that  the  effect  of  the  raw  phos- 
phate is  in  part  due  to  the  lime  which  it  carries.  In  fact,  the  ordi- 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS    261 

nary  high-grade  raw  phosphate  carries  very  little,  if  any,  lime, 
about  7  per  cent  of  calcium  carbonate  being  the  largest  amount 
in  any  high-grade  phosphate  known  to  the  author.  Tricalcium 
phosphate  is  a  neutral  substance  which  has  practically  no  power 
to  correct  soil  acidity,  except  as  the  phosphorus  is  converted  into 
the  dicalcium  or  monocalcium  compound  and  removed  from  the 
soil  by  the  growing  crop. 

Furthermore,  the  most  marked  benefit  from  the  use  of  raw  rock 
phosphate  in  Illinois  is  not  on  markedly  acid  soils,  but  on  the 
most  common  corn-belt  prairie  land,  as  on  the  Urbana  and  Gales- 
burg  experiment  fields  on  brown  silt  loams,  which  are  practically 
neutral  soils  valued  at  $150  to  $200  an  acre. 

The  Ohio  investigations  with  raw  and  acid  phosphates  are  in  a 
class  by  themselves.  No  others  have  been  conducted  anywhere 
in  the  world  that  can  compare  with  these  in  agricultural  value. 
Many  experiments  with  various  phosphates  have  been  carried  on 
for  a  single  season,  and  some  for  several  years,  but,  as  a  rule,  no 
farm  manure  has  been  used,  and  no  adequate  provision  made  for  a 
supply  of  decaying  organic  matter.  Where  nitrogen  has  been  sup- 
plied, it  has  usually  been  in  some  commercial  form,  such  as  sodium 
nitrate.  One  exception  to  this  is  found  in  the  Maryland  experi- 
ments, which  have  been  conducted  on  one  field  since  1895,  eleven 
years'  results  having  been  reported  by  Director  Patterson  (Mary- 
land Bulletin  114).  Aside  from  single  plots  treated  with  different 
acid  phosphates  and  reverted  phosphates  in  the  Crimson  Clover 
Series,  there  is  a  strictly  comparable  triplicate  test  with  (i)  raw 
bone  meal,  (2)  slag  phosphate,  (3)  no  phosphate,  (4)  South  Caro- 
lina raw  rock  phosphate,  and  (5)  Florida  soft  rock  phosphate 
(containing  phosphates  of  iron  and  aluminum).  Equal  amounts 
of  phosphorus  were  used  in  all  tests,  65^  pounds  of  phosphorus 
per  acre  having  been  applied  only  at  the  beginning  of  the  experi- 
ment. The  surface  soil  contained  1300  pounds  of  phosphorus 
in  2  million  pounds  of  the  soil. 

The  following  crops  were  grown: 

Corn  in  1895.  Wheat  in  1899.  Corn  in  1903. 

Corn  in  1896.  Hay  in  1900.  Wheat  in  1904. 

Corn  in  1897.  Hay  in  1901.  Hay  in  1905. 

Crop  failure  in  1898.       Corn  in  1902.  Corn  in  1906. 


262       SYSTEMS    OF   PERMANENT   AGRICULTURE 


In  one  series  of  tests,  crimson  clover  was  regularly  seeded  in  the 
corn  to  be  plowed  under  later  as  a  green  manure,  and  in  another 
series  rye  was  employed  in  a  similar  manner,  the  third  test  being 
made  without  special  provision  for  organic  matter.  Table  42  gives 
a  summary  of  these  investigations  for  all  forms  of  phosphorus 
that  were  used  under  the  three  different  conditions: 

TABLE  42.    MARYLAND  EXPERIMENTS  WITH  DIFFERENT  FORMS 

OF  PHOSPHORUS 
Twelve  Years'  Work  :  Yields  per  Acre  :  Average  of  Three  Plots 


Six  CORN 
CROPS,  Av. 

Two  WHEAT 
CROPS,  Av. 

THREE 
HAY 

TOTAI 

AVER- 

T*»             XT 

T>                                                               A             T       T« 

Av. 

YIELD 

Grain 

Stover 

Grain 

Stover 

(Tons; 

(Tons) 

(Bu.) 

(Tons) 

(Bu.) 

(Tons) 

8,  13,  18 

Raw  bone  meal     .     .     . 

39-6 

1.25 

23.6 

1.22 

1.85 

6.41 

9,  14,  19 

Slag  phosphate      .     .     . 

39-  * 

1.22 

22.6 

1.24 

i-95 

6.46 

10,  15,  20 

No  phosphorus     .     .     . 

40.0 

I.I7 

12.  1 

•n 

1.44 

5.10 

II,    l6,    21 

S.  C.  rock  phosphate 

39-7 

1.25 

2O.  I 

1.07 

1-95 

6.26 

12,   17,    22 

Florida  soft  rock  .     .     . 

42-5 

1.27 

19.9 

•94 

1.89 

6.19 

Here  are  represented  thirty-three  separate  tests  (three  plots  for 
eleven  years)  for  each  form  of  phosphorus.  As  an  average,  the  raw 
rock  has  given  nearly  the  same  results  as  the  bone  and  slag.  The 
average  increase  in  yield  is  very  marked  with  wheat,  less  marked 
with  hay,  and  practically  no  effect  is  seen  with  corn.  The  value 
of  the  total  increase  in  twelve  years  is  about  ten  times  the  cost  of 
the  raw  rock  phosphate,  at  Illinois  prices,  and  still  more  at  Mary- 
land prices,  for  farm  produce.  In  commenting  upon  his  experi- 
ments, Director  Patterson  says: 

"The  results  obtained  with  the  insoluble  phosphates  has  cost  usually  less 
than  one  half  as  much  as  that  with  the  soluble  phosphates. 

"The  results  show  decidedly  that  plants  are  able  to  utilize  insoluble  rock 
phosphates. 

"The  use  of  an  abundance  of  organic  matter  in  the  soil  when  insoluble 
phosphates  are  applied  was  evidently  a  necessity  for  their  best  effects. 

"Soluble  phosphates  produced  the  best  yield  of  wheat. 

"Florida  soft  phosphate  produced  the  best  yield  of  corn. 

"Reverted  phosphates  produced  the  best  yield  of  hay. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     263 

"Insoluble  South  Carolina  phosphate  rock  produced  a  higher  total  average 
yield  than  dissolved  South  Carolina  rock. 

"Florida  soft  phosphate  is  chiefly  an  aluminum-iron  phosphate  which 
occurs  in  large  quantities  deposited  in  many  parts  of  that  state.  It  is  not  well 
adapted  to  treatment  with  acid  for  making  soluble  phosphates,  as  the  aluminum 
and  iron  make  a  sticky  mass  which  is  hard  to  dry  and  keep  in  a  good  mechan- 
ical condition.  The  Florida  soft  rock  has  been  largely  used  as  a  fertilizer  in  its 
natural  condition  in  some  parts  of  that  state  on  the  light,  sandy  land,  giving 
good  results.  When  used  in  this  way,  there  has  been  applied  at  the  same 
time  heavy  dressings  of  the  native  mucks  from  the  swamps  and  lakes.  This 
muck  furnishes  nitrogen  as  well  as  the  much-needed  organic  matter.  In  order 
to  have  a  complete  fertilizer,  there  is  also  applied  some  German  potash 1  salt. " 

The  Pennsylvania  Experiment  Station  has  reported  the  results 
of  an  experiment  extending  over  twelve  years  (1884  to  1895),  in 
which  four  different  kinds  of  phosphorus  were  used  in  a  four-year 
rotation  of  corn,  oats,  wheat,  and  hay  (clover  and  timothy).  Only 
one  field  was  employed,  so  that  each  crop  was  grown  only  three 
times  during  the  twelve  years. 

The  four  forms  of  phosphorus  were  (i)  acid  phosphate  made  from 
bone  black,  (2)  "  reverted  "  phosphate  made  by  mixing  equal 
weights  of  dissolved  bone  black  and  quicklime  twelve  hours  before 
application,  (3)  fine-ground  bone  meal  (containing  8  pounds  of 
nitrogen  and  35  pounds  of  phosphorus  in  300  pounds  of  bone), 
and  South  Carolina  ground  raw  rock  phosphate.  The  amounts 
applied  per  acre  in  each  four  years  were  28  pounds  of  soluble  and 
"  reverted  "  phosphorus,  and  35  pounds  in  bone  and  raw  rock. 

No  special  provision  was  made  for  supplying  decaying  organic 
matter,  but  94  pounds  of  nitrogen  (102  pounds  on  the  bone-meal 
plots)  and  83  pounds  of  potassium  (in  potassium  chlorid)  were 
applied  per  acre,  each  four  years,  to  all  phosphorus  plots  and  also 
to  two  comparison  plots  that  received  no  phosphorus.  In  addition, 
there  were  two  plots  that  received  no  application  of  plant  food. 
The  entire  experiment  was  carried  on  in  duplicate.  One  half  of 
the  fertilizer  for  the  rotation  was  applied  to  the  corn  crop  and  the 
other  half  to  the  wheat  crop. 

Table  430  gives  the  average  yields  of  all  products  harvested  dur- 

1  Most  peat  soils  and  some  sands  are  extremely  deficient  in  potassium,  and  it 
is  also  difficult  to  liberate  potassium  that  may  exist  locked  up  in  coarse  sand  grains, 
as  suggested,  for  example,  by  the  Illinois  experiments  at  Momence,  p.  474.  —  C.  G.  H. 


ing  the  entire  twelve  years,  and  Table  436  gives  the  average  re- 
sults for  the  last  four  years. 

TABLE  43.   PENNSYLVANIA  EXPERIMENTS  WITH  DIFFERENT  FORMS  OF  PHOS 
PHORUS:  YIELDS  PER  ACRE:  AVERAGE  OF  DUPLICATE  PLOTS 

(o)  Average  of  Twelve  Years'  Work 


PLOT 
Nos. 

PLANT  FOOD  APPLIED 

CORN, 

3-YEAR 

AVERAGE 

OATS, 
3-  YEAR 
AVERAGE 

WHEAT, 

3-YEAR 

AVERAGE 

HAY,  3-  YEAR 
AVERAGE  (Tons) 

Grain 
(Bu.) 

Straw 
(T.) 

Grain 
(Bu.) 

Straw 
(T.) 

Grain 
(Bu.) 

Straw 
(T.) 

A  &G 
B  &H 
C  &I 
D  &J 
E  &K 
F  &L 

NK  and  dissolved  bone  black 
NK  and  "reverted"  bone  black 
NK  and  bone  meal    .... 
NK  and  raw  rock  phosphate  . 
Nitrogen  and  potassium  only  . 
None  

48.9 
49.6 
52.0 
47.6 
40.7 
13.1 

•97 
•97 
1.04 

•95 
•83 

.CI 

43-8 

47.1 

49-4 
48.2 

45-5 
38.8 

.67 

.66 

.80 
.78 
.61 
•55 

28.2 
29.9 
31.6 
31.6 
30.6 
22.5 

I-SI 
1.  60 
1.67 
1.67 
1.40 
.98 

1.58 
1.65 
1.68 

i-57 
1.25 

1.02 

Average  of  Last  Four  Years 


A  &G 

NK  and  dissolved  bone  black 

49-3 

.98 

33-6 

.89 

22.7 

1.61 

2.05 

B  &H 

NK  and  "reverted"  bone  black 

54-3 

1.03 

38.3 

.87 

25-4 

i-5i 

2.36 

C  &I 

NK  and  bone  meal    .... 

55-o 

1.  08 

39-1 

I.OO 

25-9 

i-75 

2.40 

D  &J 

NK  and  raw  rock  phosphate  . 

50.0 

•95 

39-2 

.91 

26.3 

1.69 

2.13 

E  &K 

Nitrogen  and  potassium  only  . 

41.4 

.83 

30.8 

•59 

23-9 

1.  21 

i-93 

F  &L 

None  

12.  Q 

.4.7 

22.2 

6n 

21.4 

I.  O3 

I.4X 

By  computation  it  will  be  found  that  the  cost  of  the  nitrogen 
and  the  potassium  for  four  years  was  $24.06  per  acre  ($25.26  on  the 
bone-meal  plots);  while  the  phosphorus  for  four  years  cost  $3.36 
in  soluble  or  reverted  form,  $3.50  in  bone  ($4.70  including  the  cost 
of  nitrogen),  and  $1.05  in  the  raw  rock  phosphate,  at  the  prices 
mentioned  in  Table  24. 

At  safe  prices  for  increase  in  produce  based  upon  zo-year  aver- 
ages for  the  corn  belt :  corn  35  cents  a  bushel,  oats  30  cents,  wheat 
70  cents,  and  hay  $6  (about  $3  per  ton  being  allowed  for 
stacking,  baling,  marketing,  and  loss),  the  value  of  the  increase 
produced  in  four  years  by  $24  worth  of  nitrogen  and  potassium  is 
$11.72  per  acre  as  an  average  of  the  twelve  years,  and  $10.19  per 


USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     265 

acre  for  the  last  four  years;  while  the  value  of  the  increase  pro- 
duced by  $1.05  worth  of  raw  phosphate  (above  the  increase  pro- 
duced by  the  nitrogen  and  potassium)  was  $5.85  per  acre  as  an 
average  of  the  twelve  years,  and  $8.41  for  the  last  four  years. 

As  an  average  of  all  crops,  the  raw  phosphate  produced  larger 
yields  than  the  acid  phosphate  (dissolved  bone  black)  and  prac- 
tically the  same  yields  as  the  reverted  phosphate  (including  lime)  ; 
but  the  bone-meal  plots  gave  slightly  larger  average  yields,  the 
increase  from  $4.70  worth  of  bone  meal  being  $8.41  per  acre  for 
four  years  as  an  average  of  the  entire  period,  and  $11.47  Per  acre 
for  the  last  four  years,  above  the  increase  produced  by  nitrogen 
and  potassium  alone. 

When  used  in  addition  to  nitrogen  and  potassium,  $1.05  worth  of 
raw  phosphate  produced  net  profits  amounting  to  $4.80  per  acre 
every  four  years  as  an  average  of  the  twelve  years,  and  $7.36  for 
the  last  four  years;  while  the  corresponding  net  profits  from  $4.70 
worth  of  bone  meal  were.  $3. 71  for  the  twelve  years'  average  and 
$6.77  for  the  last  four  years.  Thus,  the  greatest  total  net  profits 
were  from  the  raw  phosphate.  On  the  basis  of  money  invested  in 
phosphorus,  the  net  profits  from  raw  phosphate  were  457  and  700 
per  cent,  and  from  bone  meal  they  were  79  and  144  per  cent,  re- 
spectively. 

In  no  case  was  the  net  profit  from  the  use  of  phosphorus  sufficient 
to  cover  the  net  loss  from  the  use  of  nitrogen  and  potassium,  so 
that  the  total  result  was  a  net  loss  in  all  cases.  It  must  be  kept  in 
mind,  too,  that  the  effects  produced  by  phosphorus  when  used  in 
addition  to  nitrogen  and  potassium  (over  and  above  those  produced 
by  nitrogen  and  potassium  alone)  are  usually  greater  than  the 
effects  produced  by  phosphorus  when  used  alone,  as  is  fully  shown 
by  other  experiments  hereinafter  discussed. 

On  the  other  hand,  these  Pennsylvania  investigations  clearly 
indicate  that  if  the  nitrogen  were  secured  from  the  inexhaustible 
supply  in  the  air  and  turned  under  in  the  form  of  farm  manure, 
legume  crops,  or  other  residues,  and  if  the  potassium  can  be  liber- 
ated from  the  practically  inexhaustible  supply  in  the  soil  by  the 
decay  of  this  same  organic  matter,  then  the  use  of  phosphorus 
would  not  only  be  profitable  in  itself,  but  the  total  result  of  the 
system  should  yield  large  net  profits. 


266       SYSTEMS    OF   PERMANENT   AGRICULTURE 

The  soil  of  the  farm  of  the  Pennsylvania  State  College  is  a  resid- 
ual clay  loam  from  the  disintegration,  weathering,  and  leaching  of 
impure  limestone.  The  soil  contains  85  to  90  per  cent  of  fine  earth 
and  10  to  15  per  cent  of  small  stones,  quartz,  silicates,  etc.  In 
2  million  pounds  of  the  fine  earth  of  this  surface  soil  there  are  1090 
pounds  of  acid-soluble  phosphorus  and  50,700  pounds  of  total 
potassium,  an  amount  equivalent  to  $3000  worth  of  commercial 
potassium  salts. 

The  following  comments  concerning  these  experiments  are  made 
by  the  Pennsylvania  Station  (Annual  Report  for  1895,  page  210), 
on  the  basis  of  prices  prevailing  at  that  time: 

"The  yearly  average  for  the  twelve  years  gives  us  a  gain  per  year  of  $2.83 
from  insoluble  phosphorus  l  (ground  bone),  $2.45  from  insoluble  phosphorus 
(South  Carolina  rock),  $1.61  from  reverted  phosphorus,  and  48  cents  from 
soluble  phosphorus,  thus  giving  us  considerably  better  results  from  the  two 
forms  of  insoluble  phosphorus  than  from  the  reverted  or  soluble  forms,  thus 
indicating  that  the  insoluble  phosphorus  is  of  more  value  as  a  manure  than  is 
often  supposed,  and  that  it  is  worthy  of  more  attention  than  has  been  given  to 
it  in  the  past." 

In  1894,  the  Rhode  Island  Experiment  Station  began  an  inves- 
tigation to  ascertain  the  relative  value  of  eight  different  forms  of 
phosphorus,  and  a  ninth  form  (double  superphosphate)  was  intro- 
duced in  1895.  Tne  experiment  included  the  common  raw  rock 
phosphate  (containing  tricalcium  phosphate),  raw  and  roasted 
aluminum  phosphate  (containing  also  some  iron  phosphate), 
basic  slag  phosphate,  steamed  bone  meal,  and  three  acid  phos- 
phates (one  made  from  raw  rock,  one  from  bone  meal,  and  one 
from  bone  black),  besides  the  double  superphosphate.  The  fol- 
lowing statements  from  Rhode  Island  Bulletin  114  give  further 
information : 

"According  to  the  original  plan  of  Ex-Director  Flagg,  like  money  values  of 
phosphate  were  to  be  compared,  and  the  applications  were  made  for  several 
years  upon  that  basis.  Owing,  however,  to  the  widely  varying  market  prices 
from  year  to  year,  it  was  decided  in  1898  to  change  the  plan  of  the  experiment 
so  as  to  make  it  a  comparison  of  like  amounts  of  phosphorus.2 

1  Substituted  for  "  phosphoric  acid"  here  and  elsewhere. 

1  Substituted  for  "phosphoric  acid"  here  and  elsewhere,  with  equivalent  amounts. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     267 

"The  crops  of  1894  and  1895  were  Indian  corn  and  oats,  respectively. 
In  the  autumn  of  1895  the  land  was  replowed  and  seeded  to  clover  and  grass, 

as  follows: 

SEED  PER  ACRE 

Timothy 12  quarts 

Red  top 6  pounds 

Medium  red  clover    .     .     12  pounds 

"Owing  chiefly  to  the  dryness  of  the  soil,  a  stand  of  clover  was  not  secured, 
and  medium  red  clover  was  sown  again,  the  next  April,  at  the  same  rate. 

"On  account  of  the  fact  that  some  of  the  phosphates  contained  soluble 
phosphorus  while  others  were  pratically  insoluble  in  water,  all  of  the  more 
insoluble  phosphates  were  sown  broadcast  after  plowing,  and  were  then  thor- 
oughly harrowed  into  the  soil  before  seeding.  These  applications  were  made 
sufficiently  large  to  cover  the  crop  requirements  for  three  years  that  the  land 
was  expected  to  be  left  in  grass.  It  was  planned  to  divide  the  application  of 
soluble  phosphates  into  three  parts,  one  third  to  be  applied  annually  as  a  top 
dressing,  in  the  spring,  together  with  the  nitrogenous  and  potassic  manures 
which  have  been  applied  annually  at  like  rates  to  all  of  the  plots  in  both  series. 
Owing  to  the  change  in  the  plan  of  the  experiment  in  1898,  the  land  was  left  for 
an  additional  year  in  grass.  In  the  spring  of  1899  such  quantities  of  phosphates 
were  applied  as  were  supposed,  based  upon  their  composition,  to  equalize 
the  amount  of  phosphorus  upon  all  the  plots.  It  was  discovered,  however,  in 
1902,  that  the  assistant  to  whom  the  calculations  were  intrusted  in  1899  omitted 
to  take  into  account  the  applications  of  the  insoluble  phosphates  which  had 
been  made  in  the  autumn  of  1896,  and  owing  to  this  oversight  the  complete 
equalization  of  the  phosphorus  was  not  finally  accomplished  until  the  spring 
of  1902.  The  total  amount  of  phosphorus  which  was  applied  per  plot  (two 
fifteenths  acre)  to  all  excepting  the  two  check  plots,  from  1894  to  1902  inclu- 
sive, amounted  to  43  pounds,  or  to  322?  pounds  per  acre. " 

Thus,  from  1894  to  1898,  the  experiments  are  a  comparison  of 
equal  money  values  of  different  phosphates ;  from  1899  to  1901  the 
common  raw  phosphate  plots  contained  about  one  third  more 
applied  phosphorus  than  the  soluble  phosphorus  plots,  about  one 
fifth  more  than  the  bone-meal  and  slag  plots,  and  slightly  more 
than  the  aluminum  phosphate  plots. 

The  entire  experiment  was  carried  on  over  two  series  of  plots, 
one  series  having  been  given  one  ton  of  burned  lime  per  acre  in 
1894,  while  the  other  series  remained  unlimed. 

In  1901,  fourteen  different  kinds  of  plants  were  grown,  from  3  to 
8  rows  of  each  having  been  planted  across  all  of  the  plots  in  both 
series.  In  Tables  44  and  45  are  given  the  number  of  pounds  har- 
vested of  the  different  kinds  of  produce. 


268    .  SYSTEMS   OF   PERMANENT  AGRICULTURE 


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270 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


A  study  of  Table  44  shows  a  decrease  in  ear  corn  and  a  small 
increase  in  corn  stover  from  the  use  of  raw  calcium  phosphate  the 
first  year,  and  some  increase  in  both  oats  and  oat  straw  the  second 
year.  During  the  next  four  years  this  raw  rock  phosphate  produced 
a  larger  average  increase  in  the  yield  of  hay  than  any  other  form  of 
phosphorus  applied,  except  steamed  bone  meal.  This  suggests 
that  the  longer  growing  biennial  and  perennial  plants,  such  as  clover 
and  timothy,  may  be  better  able  to  utilize  the  raw  phosphate  than 
the  short-lived  annuals. 

It  is  important  to  keep  in  mind  also  that  these  four  years  con- 
stitute a  considerable  part  of  the  entire  time  of  the  experiment, 
and  that  it  was  only  during  these  four  years  that  the  investigations 
have  the  greatest  practical  significance,  because  the  first  two  years 
would  be  required  to  get  the  phosphates  thoroughly  incorporated 
with  the  soil  and  get  well  under  way  the  action  of  the  various 
agencies  that  help  to  make  the  raw  phosphates  available,  and  it 
was  only  during  the  first  six  years  that  equal  money  values  of  the 
different  phosphates  were  used.  As  stated  by  the  Rhode  Island 
Station,  "  Dehe"rain  and  other  French  writers  recommend  that, 
upon  acid  soils,  such  untreated  phosphates  should  be  applied 
several  months  or  a  year  before  liming  is  resorted  to,  so  as  to  secure 
as  great  a  decomposing  action  upon  them  by  the  soil  as  possible." 

In  1900,  the  three  largest  yields  of  ear  corn  were  produced  by 
steamed  bone  meal,  raw  calcium  phosphate,  and  roasted  aluminum 
phosphate,  in  the  order  named. 

The  results  from  the  several  crops  grown  in  1901  are  reported 
as  the  weight  of  the  fresh  or  green  crops.  It  will  be  seen  that  the 
raw  calcium  phosphate  produced  some  increase  in  eleven  of  the 
twelve  crops  reported,  and  the  average  increase  from  this  raw  rock 
phosphate  is  more  than  three  fourths  as  much  as  from  the  common 
acid  phosphate  costing  two  or  three  times  as  much  for  the  appli- 
cations made  previous  to  1901. 

The  relative  effects  of  the  different  phosphates  are  about  the 
same  on  the  unlimed  land  as  where  some  lime  had  been  applied, 
except  that  the  superiority  of  the  slag  phosphate,  steamed  bone 
meal,  and  common  raw  rock  phosphate  (calcium  phosphate)  over 
the  four  acid  phosphates  (including  superphosphate)  was  even 
more  marked  in  the  four  years'  hay  crops  on  the  unlimed  land. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     271 

As  an  average,  the  raw  calcium  phosphate  produced  more  than  90 
per  cent  as  much  increase  as  the  common  acid  phosphate  in  the 
various  crops  grown  in  1901  on  the  unlimed  land. 

The  value  of  the  increase  produced  by  the  raw  calcium  phosphate 
in  the  hay  crops  alone  is  twice  the  cost  of  all  the  phosphorus  ap- 
plied in  this  form  during  the  eight  years. 

The  value  of  the  lime  in  the  slag  phosphate  is  indicated  espe- 
cially in  the  increase  in  hay  on  the  unlimed  land.  The  aluminum 
phosphates  (which  also  contain  some  iron  phosphate)  gave  much 
poorer  results  than  the  raw  calcium  phosphate;  but  no  final  con- 
clusions should  be  drawn  regarding  this,  because  the  aluminum 
phosphate  may  not  have  been  as  finely  ground  as  the  common 
rock  phosphate,  which  in  these  experiments  was  applied  as  "  floats," 
the  dust  that  collects  about  phosphate  mills.  There  is  evidently 
no  advantage  from  roasting  the  aluminum-iron  phosphate  (Re- 
dondite). 

The  somewhat  poorer  results  obtained  with  the  double  super- 
phosphate, as  compared  with  the  other  three  acidulated  phosphates, 
is  probably  due  to  the  manufactured  land-plaster  (calcium  sulf ate) , 
which  is  a  powerful  soil  stimulant,  and  which  as  already  explained 
constitutes  about  50  per  cent  of  ordinary  acid  phosphate. 

It  will  be  noted  that  the  lime  itself  more  than  doubled  the  yield 
of  hay  as  an  average  of  all  plots,  and  also  increased  the  yield  of 
corn.  This  Rhode  Island  soil  is  acid,  and  for  most  crops  is  markedly 
improved  by  liming. 

In  commenting  upon  these  experiments,  Director  Wheeler  says 
(Rhode  Island  Bulletin  114): 

"With  the  pea,  oat,  summer  squash,  crimson  clover,  Japanese  millet  (on 
the  unlimed  land),  golden  millet,  white-podded  Adzuki  bean,  soy  bean,  and 
potato  (on  the  unlimed  land),  floats  (raw  calcium  phosphates)  gave  very  good 
results;  but  with  the  flat  turnip,  table  beet,  and  cabbage  they  were  relatively 
very  inefficient." 

"The  use  of  fine-ground  bone,  basic  slag  meal,  and  floats  has  tended  con- 
tinually to  make  the  unlimed  land  more  favorable  to  clover,  as  is  well  shown 
by  its  appearance  only  upon  those  plots  of  the  unlimed  series  where  these 
phosphates  had  been  used,  while  it  was  absolutely  lacking  where  the  raw 
and  roasted  Redondite  and  the  soluble  phosphates  had  been  applied.  Upon 
the  limed  land,  clover  has  been  uniformly  common  upon  all  the  plots." 

"Floats  can  probably  be  used  to  best  advantage  on  moist  soil,  rich  in  decay- 


272       SYSTEMS   OF   PERMANENT   AGRICULTURE 

ing  vegetable  matter,  and  for  such  crops  as  certain  legumes,  Indian  corn,  millet, 
and  possibly  wheat  and  oats,  which  seem  far  better  able  to  make  use  of  them 
than  certain  vegetables." 

In  Tables  440  and  4$c  are  recorded  the  results  obtained  in  the 
continuation  of  these  Rhode  Island  experiments,  with  soy  beans  in 
1902,  with  nineteen  different  kinds  of  plants  in  1903  (varying  from 
i  row  of  spinach  and  2  rows  of  lettuce  to  10  rows  of  barley  and  16 
rows  of  oats),  and  with  oats  in  1904. 

The  heavy  applications  made  in  the  spring  of  1902,  amounting 
to  1426  pounds  of  acid  bone  black,  1738  pounds  of  acid  bone  meal, 
and  1771  pounds  per  acre  of  acid  phosphate,  with  no  additional 
application  of  raw  calcium  phosphate,  render  the  subsequent  crop 
yields  of  less  economic  importance,  in  the  author's  opinion,  but 
they  are  of  interest  because  of  the  great  variety  of  plants  repre- 
sented, although  the  data  are  not  sufficient  to  justify  very  definite 
conclusions. 

The  following  comments  on  the  results  of  1902,  1903,  and  1904, 
are  given  in  Rhode  Island  Bulletin  118,  page  84: 

"Floats  (raw  calcium  phosphate)  gave  very  good  results  with  the  soy  beans, 
peas,  crimson  clover,  mangel-wurzel  (on  limed  land),  barley  (on  limed  land), 
potato  (on  unlimed  land),  Japanese  millet,  oats,  and  golden  millet;  but  they 
proved  highly  inefficient,  especially  for  Hubbard  squash,  rutabaga,  crookneck 
squash,  flat  turnip,  cabbage,  mangel-wurzel  (on  the  acid  unlimed  land), 
tomato,  lettuce,  New  Zealand  spinach,  and  red  valentine  bean." 

One  of  the  oldest  known  facts  concerning  plant  nutrition  is  the 
weak  power  of  turnips  and  other  plants  of  the  cabbage  family 
(Cruciferze)  to  secure  phosphorus  from  insoluble  forms.  Thus, 
almost  the  first  important  result  of  Sir  John  Lawes'  agricultural 
experiments  was  the  discovery,  seventy  years  ago,  that  dissolved 
bone  black  was  very  much  more  efficient  than  the  untreated  ma- 
terial for  the  production  of  turnips. 

In  no  case  in  the  Rhode  Island  results  for  1902,  1903,  or  1904, 
with  soy  beans,  crimson  clover,  millet,  or  oats  (representing  the 
farm  grains,  grasses,  and  legumes)  was  the  increase  from  acid  phos- 
phate double  the  increase  from  raw  calcium  phosphate,  and  as  an 
average  of  the  results  with  these  crops  (on  limed  or  on  unlimed 
plots)  the  increase  from  acid  phosphate  was  not  more  than  i£ 
times  that  from  the  raw  calcium  phosphate,  although  the  cost  of 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS 


273 


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274       SYSTEMS   OF   PERMANENT   AGRICULTURE 


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USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS 


275 


the  acid  phosphate  applied  is  three  times  that  of  the  raw  rock; 
and  it  should  be  kept  in  mind  that  no  provision  was  made  to  keep 
the  soil  supplied  with  decaying  organic  matter,  although  nitrogen 
and  potassium,  in  commercial  form,  were  applied  to  all  plots  alike. 
If  we  add  together  all  of  the  grain  and  hay  produced  during  the 
decade  following  the  first  year  of  the  experiment,  including  the 
oat  grain  in  1895,  the  hay  in  1896,  1897,  1898,  1899,  and  1904, 
the  ear  corn  in  1900,  and  the  soy  beans  in  1902,  we  secure  the 
following  totals  for  the  plots  designated : 


SOIL  TREATMENT 

No  PHOSPHATE 

ROCK  PHOSPHATE 
(CA) 

ACID  PHOSPHATE 

Unlimed 

Limed 

Unlimed 

Limed 

Unlimed 

Limed 

Pounds  per  acre    .     .     . 
Gain  for  phosphorus 
Gain  for  lime  .... 

83IO 

27470 

22890 
14580 

35340 
7870 
12450 

22860 
1455° 

37000 
9530 
14140 

19160 

These  figures  present  in  very  concise  form  an  economic  summary 
of  the  Rhode  Island  experiments  with  "  floats"  and  acid  phosphate, 
as  applied  to  the  more  valuable  produce  of  the  general  farm  crops 
grown  during  the  ten  years.  The  acid  phosphate  gave  slightly 
poorer  results  than  the  raw  rock  on  the  unlimed  land  and  20  per 
cent  better  results  on  the  limed  land.  The  value  of  lime  is  also 
strikingly  shown.  It  should  be  kept  in  mind,  however,  that  the 
more  abundant  growth  of  clover  upon  the  limed  land  during  the 
four  years,  1896  to  1899,  would  likely  benefit  succeeding  crops, 
irrespective  of  the  lime  itself. 

The  Maine  Experiment  Station  reports  two  series  of  experiments 
with  different  phosphates,  one  covering  a  period  of  nine  years  with 
all  tests  in  triplicate  on  2oth-acre  plots  where  equal  amounts  of 
phosphorus  were  compared,  and  the  other  for  five  years  (1890  to 
1894)  on  2^-acre  plots  where  equal  money  values  of  phosphorus 
were  compared. 

In  the  nine-year  experiments,  fertilizers  were  applied  five  times  — 
in  1886,  1887,  1889,  1893,  and  1894.  When  applied,  the  amounts 
per  acre  were  200  pounds  of  ammonium  sulfate,  100  pounds  of 
potassium  chlorid,  360  pounds  of  fine-ground  bone,  300  pounds  of 


276       SYSTEMS    OF   PERMANENT   AGRICULTURE 

fine-ground  South  Carolina  raw  rock  phosphate;  and,  for  soluble 
phosphorus,  400  pounds  of  acidulated  bone  black  were  used  for 
1886,  1887,  and  1889,  and  500  pounds  of  acid  phosphate  made  from 
South  Carolina  rock  for  1893  and  1894.  The  stable  manure  was 
applied  five  times  at  the  rate  of  20  tons  per  acre.  The  results  are 
reported  in  Table  46  for  each  of  the  eight  crops  harvested. 

TABLE  46.   MAINE  EXPERIMENTS  WITH  .DIFFERENT  PHOSPHATES 
Pounds  per  Acre  of  Air-dry  Produce:  Average  of  Three  Plots  in  Each  Case 


TREATMENT  APPLIED 

NONE 

NK 

AND 

ACID 
PHOS- 
PHATE 

NK 

AND 

BONE 

MEAL 

NK 

AND 

RAW 
PHOS- 
PHATE 

•NK 
ONLY 

STABLE 
MANURE 

1886  Oats,  grain  .     .     . 
1886  Oat  straw    .     .     . 

1670 
1994 

2486 
34M 

2286 
3J34 

2l66 

2886 

% 

1936 
2564 

22l6 
3050 

1887  Oats,  grain  .     .     . 
1887  Oat  straw    .     .     . 

800 
I20O 

1160 

2240 

956 
1610 

1064 
2036 

1052 
1648 

1014 
2060 

1888  Hay    
1889  Fallow    .... 

1890  Peas,  grain  .     .     . 
1890  Pea  straw    .     .     . 

2566 

2434 

2800 

2566 

2234 

4010 

742 
664 

902 
948 

946 
976 

848 
914 

762 
660 

1360 
1284 

1891  Oats,  grain  .     .     . 
1891  Oat  straw    .     .     . 

1166 
726 

1346 
986 

1376 
1090 

1160 
776 

1296 
704 

1542 
1746 

1892  Peas,  grain  .     .     . 
1892  Pea  straw    .     .     . 

468 
748 

368 
756 

376 
696 

308 
552 

440 
740 

588 
I388 

1893  Corn,  total  .     .     . 
1894  Corn,  total  .     .     . 

395 
749 

1415 
2926 

1326 
3038 

1076 
2631 

905 
I879 

2931 
3502 

Total  yield,  8  crops  .     . 
Total  increase       .     .     . 
Gain  for  phosphorus 

13888 

21381 

7493 
456i 

20610 
6722 
379° 

18983 

5°95 
2163 

16820 
2932 

26751 
12863 

Of  the  different  forms  of  phosphorus,  the  acid  phosphate  gave  the 
best  results  for  the  first  two  years,  especially  in  oat  straw,  but 
afterward  the  bone  meal  gave  the  best  results.  The  raw  phosphate 
produced  only  about  one  half  as  much  increase  as  the  other  forms, 
but  at  less  than  one  third  the  cost. 


USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     277 

In  the  other  phosphate  experiment  by  the  Maine  Station,  cover- 
ing five  years  on  a  zo-acre  field  divided  into  four  2^-acre  plots,  the 
fertilizer  applications  were  made  but  once  (in  1890).  The  amounts 
applied  per  acre  were  20  loads  of  stable  manure  on  plot  i,  and  66 
pounds  of  sodium  nitrate,  16  pounds  of  ammonium  sulfate,  and  100 
pounds  of  potassium  chlorid  (supplying  only  14  pounds  of  nitro- 
gen and  42  pounds  of  potassium)  on  plots  2  and  3.  In  addition, 
plot  2  received  1000  pounds  of  raw  rock  phosphate  (containing  107 
pounds  of  phosphorus),  and  plot  3  received  500  pounds  of  acid 
phosphate  (containing  35  pounds  of  phosphorus),  per  acre.  Plot  4 
received  no  fertilizer. 

Table  47  gives  the  results  obtained  for  the  five  years  of  the 
experiment,  and  also  the  average  yields  of  hay  for  two  years  before 
the  fertilizers  were  applied. 

TABLE  47.   MAINE  EXPERIMENTS  WITH  EQUAL  MONEY  VALUES  OF  RAW 

PHOSPHATE  AND  ACID  PHOSPHATE 
Pounds  per  Acre  of  Air-dry  Produce 


PLOT  No.       .                ... 

1 

2 

3 

4 

TREATMENT  APPLIED,  1890  ONLY 

STABLE 

MANURE 

NK. 

AND 

RAW 
PHOS- 
PHATE 

NK 

AND 

ACID 
PHOS- 
PHATE 

NONE 

1888  and  1889  Hay,  average  yield     . 

2542 

2416 

2082 

2510 

1890  Barley  and  peas,  total      .     .     . 
1891  Oats,  grain    

2208 

1^6 

1712 
1447 

1422 

IC22 

1118 

I  3OA 

1891  Oat  straw      

2282 

1  c?4 

1440 

1176 

1892  Barley  hay     

244.4 

2^24 

IQ7O 

1161 

1892  Fallow 

1894  Oats,  total     

1804 

24?2 

17-24 

O<7 

Total  yield,  1890  and  1891       .     .     . 
Total  yields,  1892,  1894      .... 

6026 
5338 

4693 

4777 

4394 
3664 

3598 

2118 

278        SYSTEMS   OF   PERMANENT   AGRICULTURE 

These  data  show  that  the  first  two  years  after  application  the 
acid  phosphate  gave  about  the  same  results  as  the  raw  phosphate, 
but  the  last  two  crops  gave  better  results  from  the  raw  phosphate, 
even  when  compared  with  the  original  apparent  difference  in  the 
productive  power  of  the  two  plots,  —  a  difference  which  may  or 
may  not  hold  for  other  crops  in  other  years. 

In  commenting  on  these  experiments,  Director  Jordan  said 
(Maine  Report,  1894,  page  31): 

"With  the  exception  of  the  oat  crop  of  1891  the  production  of  plot  two  has 
largely  exceeded  that  of  plot  three.  Especially  is  this  true  of  the  1894  crop 
after  the  exhausting  effect  of  three  years  of  cropping.  .  .  .  This  is  certainly 
one  instance  of  the  unmistakable  persistent  influence  of  a  crude  phosphate 
in  increasing  the  growth  of  a  field  crop." 

According  to  Doctor  Jordan,  the  20  loads  of  stable  manure  con- 
tained 172  pounds  of  nitrogen,  50  pounds  of  phosphorus,  and  146 
pounds  of  potassium. 

The  Massachusetts  Experiment  Station  has  reported,  with  the 
following  explanations,  an  experiment  with  different  kinds  of 
phosphates,  extending  over  n  years,  1890  to  1900  (see  9th,  loth, 
and  i3th  Annual  Reports) : 

"This  series  of  experiments  was  begun  by  Doctor  Goessman  in  1890,  with 
a  view  of  determining  whether  it  is  not  more  profitable  to  employ  one  of  the 
cheaper  natural  phosphates  than  to  use  the  more  costly  acid  phosphate." 

"The  field  was  first  divided  into  five  plots,  containing  about  6600  square  feet 
each.  These  plots  received  equal  money's  worth  (on  the  basis  of  prices  in  1890) 
of  the  phosphates  used,  as  follows: 

Plot  i.   Phosphatic  slag. 

Plot  2.   Mona  guano. 

Plot  3.  Apatite  at  first ;  later  Florida  phosphate. 

Plot  4.   South  Carolina  phosphate. 

Plot  5.  Dissolved  bone  black. 

"Plot  3,  as  above  stated,  received  an  application  of  ground  apatite  in  1890. 
In  1891  it  was  found  impossible  to  obtain  this  material,  and  no  phosphate  of 
any  kind  was  applied  to  the  plot.  In  1892  and  1893  ground  hard  Florida 
phosphate  was  applied  to  this  plot.  It  is  not  believed,  however,  that  it  is  fair 
to  this  phosphate  to  compare  it  with  the  others,  since  it  has  been  used  only 
two  years,  while  the  others  have  been  applied  for  four  years. 

"From  the  beginning,  each  of  these  five  plots  has  received  the  same  applica 
tion  of  nitrate  of  soda  and  potash-magnesia  sulfate.  The  quantities  of  these 
applied  per  plot  during  the  first  four  years  were  about  44  pounds  of  the  former 
and  66  pounds  of  the  latter. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS 


279 


"Since  1894  no  phosphate  of  any  kind  has  been  applied  to  these  plots,  but 
the  quantity  of  nitrate  of  soda  and  of  potash-magnesia  sulfate  has  been  used  in 
one  half  greater  quantities. 

"At  first  Doctor  Goessman  included  no  plot  on  which  phosphate  was  not  used 
for  comparison  with  the  others.  Later  such  a  plot  was  added,  but  it  was  left 
entirely  unmanured  until  1896.  During  1896  and  1897  it  has  received  the 
nitrate  of  soda  and  potash-magnesia  sulfate  at  the  same  rate  as  the  other  plots." 

The  data  (excepting  from  plot  3)  are  recorded  in  Table  48. 

TABLE  48.  MASSACHUSETTS  EXPERIMENTS  WITH  EQUAL  MONEY  VALUES  OF 

DIFFERENT  PHOSPHATES 
Pounds  per  Plot  (about  6600  Square  Feet) 


PLOT  No  

0 

1 

2 

4 

5 

PHOSPHATE  APPLIED 

NONE 

SLAG 
PHOS- 
PHATE 

GUANO 
PHOS- 
PHATE 

s.c. 

RAW 
PHOS- 
PHATE 

ACID 
BONE 
BLACK 

1890  Potatoes 

1600 
67. 

3*3 

814 

470 
1190 

169 

221 

195 
500 

254 
426 

1870 

1415 

73 
267 

682 

57i 
810 

148 
251 

1  66 
465 

233 
540 

3655 

l830 

78 
302 

622 

580 
890 

144 

216 

189 

57° 

252 
500 

1965 

2I2O 

59 

346 

584 

542 
780 

118 

272 

185 
440 

247 
495 

1619 

1891  \Vheat  grain 

1891  Wheat  straw 

1892  Serradella  (air-dry)    
1893  Ear  corn                     ... 

1893  Corn  stover 

1894  Barley  grain 

1894  Barley  straw 

i  So1?  Rve  srrain 

1895  Rye  straw 

1896  Soy  beans  grain 

1896  Soy  bean  straw     

830 

1897  Swede  turnips  (roots)     .... 
1898  Corn 

1899  Oats  
1900  Cabbage  (heads)  

103 

9OO 

830 

1500 

1095 

Pounds  per  Acre 


1890-1893  Phosphorus  applied  .     .     . 
1890-1900  Phosphorus  removed      .     . 

None 

278 
124 

207 

121 

416 

122 

142 

116 

1900  Balance  not  removed     .... 

154 

86 

294 

26 

T» 

280        SYSTEMS    OF   PERMANENT   AGRICULTURE 

The  record  for  yields  for  1898  and  1899  appears  not  to  have  been 
published,  but  the  report  states  that  in  1898  the  yield  of  corn  was 
good  upon  all  of  these  phosphate  plots,  and  that  there  was  but 
little  difference  between  the  yields  of  oats  on  the  different  plots 
in  1899.  In  the  Report  for  1900  the  following  summaries  are  made 
by  Professor  Brooks: 

"Taking  into  account  all  of  the  crops  which  have  been  grown  upon  this 
field,  except  the  Swedish  turnips  (rutabaga),  which  were  affected  by  disease 
not  apparently  due  to  the  fertilizer  which  had  been  used  on  a  portion  of  the 
plots,  and  the  yields  of  which,  therefore,  as  expressed  in  figures,  would  be  mis- 
leading, and  representing  the  aggregate  yield  which  stands  highest,  by  100,  the 
efficiency  of  the  different  phosphates  is  as  follows : 

Phosphatic  slag        .         .  .     100.0 

Ground  South  Carolina  rock  .       92.3 

Dissolved  bone  black       .  .       90.7 

Mona  guano   .         .         .  .88.3 

"There  was  at  first  no  no-phosphate  plot  used  in  the  experiment,  but  we  have 
had  a  no-phosphate  plot  since  1895.  Taking  into  account  the  yields  of  the 
several  plots  since  1895,  and  excepting  the  Swedish  turnips,  which  were  grown 
in  1897,  for  reasons  above  stated,  the  phosphates  have  the  following  relative 
rank: 

South  Carolina  rock  phosphate  100.0 
Phosphatic  slag  .  .  .99.0 
Dissolved  bone  black  .  .  97.7 
Mona  guano  ....  95.4 
No  phosphate  .  .  .55.4 

"The  following  conclusions  appear  to  be  justified  by  the  results  which  we 
have  obtained: 

"It  is  possible  to  produce  profitable  crops  of  most  kinds  by  liberal  use  of 
natural  phosphates,  and  in  a  long  series  of  years  there  might  be  a  considerable 
money  saving  in  depending,  at  least  in  part,  upon  these  rather  than  upon  the 
higher  priced  dissolved  phosphates." 

"Between  ground  South  Carolina  rock,  Mona  guano,  and  the  phosphatic 
slag  there  is  no  considerable  difference  in  the  economic  result." 

It  will  be  seen  that  the  South  Carolina  rock  phosphate  produced 
larger  yields  than  the  dissolved  bone  black  with  all  of  the  fourteen 
different  crop  products  reported,  excepting  potatoes  the  first  year, 
wheat  straw  the  second  year,  and  barley  straw  the  fifth  year.  It 
should  be  kept  in  mind,  too,  that  no  adequate  provision  was  made 
.  for  supplying  decaying  organic  matter  to  this  soil  during  the  eleven 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     281 

years  of  the  experiment,  and  we  have  the  following  statement  from 
the  Massachusetts  Report  for  1896,  page  190,  concerning  the  earlier 
history  of  this  field: 

"Previous  to  1887  it  was  used  as  a  meadow,  which  was  well  worn  out  at  that 
time,  yielding  but  a  scanty  crop  of  English  hay.  During  the  autumn  of  1887 
the  sod  was  turned  under  and  left  in  that  state  over  winter.  It  was  decided 
to  prepare  the  field  for  special  experiments  with  phosphates  by  systematic  ex- 
haustion of  its  inherent  resources  of  plant  food.  For  this  reason  no  manurial 
matter  of  any  description  was  applied  during  the  years  1887,  1888,  and  1889. 

"The  soil,  a  fair  sandy  loam,  was  carefully  prepared  every  year  by  plowing 
during  the  fall  and  in  the  spring,  to  improve  its  mechanical  condition ;  during 
the  same  period  a  crop  was  raised  every  year." 

A  second  series  of  experiments  with  different  phosphates  was 
begun  by  the  Massachusetts  Station  in  1897,  upon  thirteen  plots 
of  land  that  had  all  received  600  pounds  of  bone  meal  per  acre  in 
1896.  In  this  series  equal  amounts  of  phosphorus  are  being  applied 
in  ten  different  phosphates.  The  results  thus  far  reported  are 
variable  and  inconclusive.  In  some  cases  soluble  phosphates  have 
produced  the  best  yields,  especially  upon  garden  vegetables,  while 
in  some  other  cases  the  raw  phosphates  have  given  better  results. 
Of  course  the  600  pounds  of  bone  meal  applied  to  the  entire  field 
in  1896  greatly  reduced  the  need  for  phosphorus  for  some  years. 
The  published  data  are  given  in  Table  49.  (See  Massachusetts 
Reports  1898  to  1907.) 

In  the  report  for  1903,  Professor  Brooks  makes  the  following 
comments  concerning  the  cabbage  crops: 

"Apatite  and  soft  Florida  phosphate  are  the  least  effective  among  the  phos- 
phates employed. 

"South  Carolina  rock  gives  a  surprisingly  good  return,  being  exceeded  in 
yield  of  hard  heads  by  only  one  plot,  —  the  one  receiving  dissolved  bone,  — 
while  in  total  yield  it  is  materially  exceeded  by  but  "few. 

"The  phosphatic  slag  ranks  among  the  best  of  the  phosphates." 

Professor  Brooks  also  makes  the  following  general  statements 
concerning  these  phosphate  experiments: 

"In  estimating  the  significance  of  the  results  upon  this  field,  it  is  important 
to  keep  in  mind  the  facts  as  regards  the  character  of  the  soil.  It  is  what  would 
be  called  a  strong  and  moderately  heavy  loam,  and  has  great  capacity  to  retain 
moisture.  The  relatively  insoluble  phosphates  are  known  to  give  better  results 
on  soils  of  this  character  than  on  those  which  are  lighter  and  drier." 


282       SYSTEMS    OF   PERMANENT   AGRICULTURE 


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USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     283 

"It  appears  reasonable  to  believe  that  on  soils  of  the  character  of  this  field 
the  farmer  may  safely  depend  for  a  considerable  portion  at  least  of  the  phos- 
phorus needed  by  his  crops  upon  the  cheaper  natural  phosphates,  such  as  finely 
ground  South  Carolina  rock  and  finely  ground  bone,  while  phosphatic  slag  also 
promises  to  give  a  most  useful  fertilizer  upon  soil  of  this  character." 

This  entire  field,  including  the  no-phosphate  plot,  has  received 
52  pounds  of  nitrogen  and  126  pounds  of  potassium  per  acre  per 
annum  for  the  ten  years.  The  phosphate  plots  have  each  received 
42  pounds  of  phosphorus  per  acre  each  year;  but  no  provision  was 
made  for  maintaining  organic  matter  in  the  soil.  It  should  also 
be  kept  in  mind  that  the  raw  phosphates  that  gave  poor  results 
may  not  have  been  ground  to  a  sufficient  degree  of  fineness. 

The  Illinois  Experiment  Station  is  conducting  much  more  ex- 
tensive experiments  than  any  other  state  with  the  use  of  fine- 
ground  natural  rock  phosphate,  but  these  investigations  were  begun 
too  recently  to  furnish  information  from  which  such  final  conclu- 
sions can  be  drawn  as  from  the  Ohio  work,  for  example. 

In  Table  50  are  reported  results  obtained  from  the  University 
of  Illinois  soil  experiment  field  near  Galesburg,  Knox  County,  on 
the  ordinary  brown  silt  loam  prairie  soil  of  the  Upper  Illinoisan 
glaciation,  which,  in  1903,  contained  in  2  million  pounds  of  the 
surface  soil  5020  pounds  of  nitrogen,  1160  pounds  of  total  phos- 
phorus, and  31,700  pounds  of  potassium. 

A  six-year  rotation  is  under  way  on  this  field,  including  corn  for 
two  years,  oats  the  third  year,  and  wheat  the  fourth,  followed  by 
two  years  of  clover  and  timothy.  (After  the  first  six  years  the 
rotation  will  be  corn,  corn,  oats,  clover,  wheat,  clover.)  There  are 
three  independent  series  of  plots,  so  that  every  year  corn  is  grow- 
ing on  one  series,  oats  or  wheat  on  another  series,  and  clover  and 
timothy  on  the  other. 

The  land  was  timothy  sod  at  the  beginning,  and  Series  300  was 
not  broken  during  the  first  two  years,  ^  ton  of  phosphate  per  acre 
having  been  applied  at  the  beginning  as  a  top  dressing,  which,  as 
was  expected,  produced  practically  no  effect.  A  ton  of  phosphate 
per  acre  applied  in  the  beginning  to  Series  200  produced  no  effect 
on  the  oats  seeded  on  timothy  sod  in  1904,  and  but  little  effect 
on  the  wheat  which  followed  in  1905.  The  regular  plan  is  to  apply 
i^  tons  of  raw  rock  phosphate  per  acre  to  the  clover  and  timothy 


284       SYSTEMS    OF   PERMANENT  AGRICULTURE 

sod  before  plowing  for  corn,  and  this  application  will  probably  be 
repeated  every  six  years  until  the  total  phosphorus  content  of  the 
plowed  soil  is  about  doubled,  after  which  the  amounts  applied  for 
each  rotation  will  be  reduced  to  supply  only  about  as  much  phos- 
phorus as  is  removed  in  the  crops  grown. 

'  The  heavy  applications  of  phosphorus  that  will  thus  be  made 
during  the  first  three  or  four  rotations  cost  about  $1.88  per  acre 
per  annum,  which  is  less  than  is  commonly  expended  for  "  com- 
plete "  fertilizers  in  the  older  states,  in  a  system  that  supplies  less 
phosphorus  than  is  removed  in  the  crops  grown  and  that  thus 
leaves  the  land  poorer  year  by  year.  (An  application  of  200 
pounds  of  "  2-8-2  "  fertilizer  l  would  furnish  less  than  9  pounds  of 
total  phosphorus  and  at  an  average  cost  of  at  least  $2.) 

Different  systems  of  supplying  organic  matter  are  followed  upon 
the  different  plots  numbered  in  Table  50  (legume  catch  crops,  crop 
residues,  and  farm  manure),  so  that  the  same  yields  are  not  to  be 
expected  upon  plots  2,  3,  4,  and  5,  for  example;  but  these  four 
plots  differ  from  the  next  four  only  by  the  application  of  phos- 
phorus to  plots  6,  7,  8,  and  9.  For  the  student  of  details,  it  may  be 
said  that,  aside  from  the  phosphorus  applied,  plot  5  is  treated  the 
same  as  plot  6,  while  plots  2,  3,  and  4  are  treated  the  same  as  plots 
7,  8,  and  9,  respectively. 

Of  course,  the  benefits  of  the  crop  rotation,  including  the  use  of 
different  methods  of  supplying  organic  matter  and  nitrogen, 
cannot  be  determined  before  even  the  first  rotation  is  completed; 
and  the  results  thus  far  secured  from  the  phosphorus  applied  are 
to  be  considered  very  preliminary.  They  show  but  little  of  what 
it  is  reasonable  to  expect  from  the  system  when  fully  under  way 
after  the  benefit  of  one  or  two  full  rotations  is  felt. 

In  the  last  column  of  Table  50  are  given  the  values  of  the  in- 
creases produced  by  the  raw  rock  phosphate,  including  the  yearly 
totals  from  the  three  crops;  that  is,  from  three  acres.  By  keeping 
in  mind  that  the  annual  cost  of  the  phosphate  for  three  acres  is 
$5-63  (while  the  heavy  applications  are  being  made),  the  financial 
progress  of  the  experiment  during  the  first  five  years  is  seen  at  a 
glance.  In  round  numbers,  the  increase  paid  50  per  cent  interest 

1  This  means  a  per  cent  of  ammonia  (NHg),  8  per  cent  of  available  "phosphoric 
acid"  (PjOs),  and  2  per  cent  of  potash  (K2O). 


USE    OF   PHOSPHORUS   IN   DIFFERENT  FORMS     285 


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286       SYSTEMS   OF    PERMANENT   AGRICULTURE 

on  the  investment  in  the  first  three  years,  and  during  the  next  two 
years  it  paid  the  annual  cost  and  40  per  cent  net  profit  on  the  same. 

The  results  of  the  Galesburg  field  are  in  harmony  with  those  thus 
far  secured  from  many  other  University  of  Illinois  soil  experiment 
fields  in  different  parts  of  the  state,  and  they  are  also  in  harmony 
with  numerous  practical  tests  by  progressive  Illinois  farmers  who 
make  adequate  provision  for  supplying  the  soil  with  decaying 
organic  matter.  Thus,  as  an  average  of  four  independent  tests  on 
each  experiment  field,  Tennessee  raw  rock  phosphate  increased  the 
yield  of  corn  in  1908  by  12.1  bushels  per  acre  on  the  Galesburg 
field,  by  11.9  bushels  on  the  Myrtle  field  for  first-year  corn  and  9.3 
bushels  for  second-year  corn,  by  16.0  bushels  on  the  Rockford 
field  for  first-year  corn  and  7.6  bushels  for  second-year  corn,  by 
3.5  bushels  on  the  Antioch  field,  by  9.1  on  the  Auburn  field,  and 
by  8.4  bushels  on  the  Urbana  field. 

These  experiment  fields  are  in  six  different  counties,  and  they 
have  been  in  operation  from  four  to  six  years.  The  average  yield 
of  corn  in  1908  was  67.3  bushels  where  raw  phosphate  has  been 
applied  and'  57.5  bushels  without  phosphorus.  The  phosphate 
applied  thus  far  adds  phosphorus  to  the  soil  at  the  rate  of  60  pounds 
or  more  per  year,  while  16  pounds  are  required  for  a  68-bushel  crop 
and  about  2  pounds  for  the  ic-bushel  increase.  Thus,  the  value 
of  the  increase  ($3.43)  will  pay  the  cost  of  the  phosphate  (less 
than  $2)  and  leave  50  per  cent  net  profit,  and  with  70  per  cent  of 
the  phosphorus  left  in  the  soil. 

The  effect  on  wheat  and  clover  is  almost  as  marked  as  on  corn. 
Of  course,  more  clover  means  more  nitrogen  secured  from  the  air, 
and  it  may  also  mean  more  manure  to  return  to  the  soil.  Mean- 
while, the  untreated  land  grows  poorer  year  by  year. 

In  Table  51  are  given  the  results  reported  by  the  Illinois  Experi- 
ment Station  (Circular  97)  from  a  series  of  pot  cultures  conducted 
for  the  purpose  of  comparing  equal  money  values  of  raw  rock  phos- 
phate and  steamed  bone  meal.  In  the  Illinois  field  experiments, 
the  standard  annual  application  of  phosphorus  is  25  pounds  per 
acre  in  200  pounds  of  steamed  bone  meal  and  nearly  equal  money 
values  of  other  forms  of  phosphorus.  The  25  pounds  is  based  upon 
the  requirements  of  a  loo-bushel  crop  of  corn,  with  i  or  2  pounds 
for  lo-s  in  drainage.  In  pot  cultures  very  large  crops  are  commonly 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS     287 

produced,  and  to  meet  the  needs  of  such  crops  the  applications  of 
plant  food  are  made  three  times  as  large  as  in  field  experiments. 
The  soil  used  was  from  the  gray  silt  loam  prairie  of  the  lower 
Illinoisan  glaciation,  and  wheat  was  the  crop  grown  in  the  pots. 
The  phosphate  used  is  known  as  the  Tennessee  blue  rock.  In  cer- 
tain pots  the  phosphorus  was  turned  under  with  a  good  growth  of 
clover;  in  other  pots  with  farm  manure,  and  in  others  with  both 
clover  and  manure. 

TABLE  51.   COMPARATIVE  EFFECTS  OF  STEAMED  BONE  MEAL  AND  RAW  ROCK 
PHOSPHATE,  IN  CONNECTION  WITH  CLOVER  AND  MANURE 


PARTIAL  TREATMENT 
APPLIED 

SERIES  100, 
WITHOUT  POTASSIUM, 
WHEAT  YIELDS 

SERIES  200, 
WITH  POTASSIUM, 
WHEAT  YIELDS 

Grams 
per  Pot 

Increase  in 
Grams 

Grams 
per  Pot 

Increase  in 
Grams 

None   

IO.O 
I6.3 

14-7 
14.2 
22.2      . 

23-3 

I6.5 
22-7 

19.4 

19-5 

24.1 

23-3 

6-3 

4-7 

4-2 
12.2 

13-3 

6-5 
12-7 

9-4 
9-5 
I3-1 

i3-3 

"•3 

18.4 

18.4 
18.2 
21.9 
21.9 

18.1 
19.1 

19-3 

19.0 

25-3 
25-3 

!-3 

8.4 
8.4 

8.2 

11.9 
11.9 

8.1 
9.1 

9-3 
9.0 

15-3 

15-3 

Clover      

Rock  phosphate     

Clover,  bone  meal      

Clover,  rock  phosphate  .     . 

Manure    

Clover,  manure      

Manure,  bone  meal    

Manure,  rock  phosphate     .... 
Clover,  manure,  bone  meal      .     .     . 
Clover,  manure,  rock  phosphate  .     . 

It  will  be  seen  that  the  untreated  soil  (pot  101)  yielded  10  grams 
of  wheat.  Where  clover  was  turned  under  (102),  the  yield  was  in- 
creased by  6.3  grams,  and  where  bone  meal  was  turned  under  with 
clover  (105),  the  yield  was  22.2  grams,  the  increase  of  12.2  grams 
being  nearly  'double  that  produced  by  clover  without  bone  meal. 

Where  raw  rock  phosphate  was  turned  under  with  clover  (106), 
the  wheat  yielded  23.3  grams,  making  a  total  increase  of  13. 3  grams 
over  the  yield  of  the  untreated  soil.  Of  this  increase  6.3  grams 
should  be  credited  to  the  clover  and  7  grams  to  the  rock  phosphate, 
by  one  computation;  or  4.2  to  the  phosphate  and  9.1  to  the  clover, 
by  the  other  route.  Thus,  rock  phosphate  used  alone  produced  an 


288       SYSTEMS    OF   PERMANENT   AGRICULTURE 


increase  of  only  4.2  grams,  which,  added  to  the  increase  of  6.3  grams 
due  to  clover  alone,  makes  only  10.5  grams.'  In  other  words,  the 
sum  of  the  gains  which  they  make  when  used  separately  was  2.8 
grams  less  than  the  increase  produced  when  the  rock  phosphate 
and  clover  were  turned  under  together.  Somewhat  similar  results 
are  produced  with  clover  and  bone  meal  when  used  separately  and 
together;  also  with  bone  meal  and  potassium,  and  with  rock 
phosphate  and  potassium.  Such  marked  combined  action  does  not 
appear,  however,  from  other  combinations,  possibly  because  of 
other  limiting  factors.  As  a  general  average,  the  rock  phosphate 
has  made  slightly  better  gains  than  the  steamed  bone  meal. 

The  pots  used  in  these  investigations  are  io|-  inches  in  diameter, 
consequently  i  gram  per  pot  corresponds  to  i  pound  per  square 
rod,  or  to  160  pounds  per  acre.  The  actual  yields  in  grams  per  pot 
are  given,  but  the  results  may  also  be  computed  to  bushels  per 
acre.  It  should  be  remembered  that  pot  cultures  constitute  an 
intensive  form  of  agriculture.  They  are  carried  on  under  almost 
complete  control,  except  in  very  warm  weather,  when  too  much 
shade  may  be  required  to  avoid  too  high  temperature.  The  yields 
obtained  are  usually  two  or  three  times  as  much  as  can  be  expected 
in  the  field  under  ordinary  weather  conditions.  They  are  not, 
however,  larger  than  could  be  obtained  in  the  field  under  perfect 
weather  conditions.  The  largest  yield  reported  in  Table  51  is  25.3 
grams  per  pot,  or  67  bushels  of  wheat  per  acre.  Pot  culture  yields 
have  been  produced  corresponding  to  142  bushels  of  wheat,  and 
to  230  bushels  of  oats,  per  acre. 

Doctor  Alfred  M.  Peter  of  the  Kentucky  Station  has  kindly 
furnished  the  author  the  following  data  secured  by  him  with  the 
cooperation  of  Mr.  S.  C.  Jones  of  the  Kentucky  Geological  Survey: 

KENTUCKY  EXPERIMENTS:    POT  CULTURES 


TREATMENT  APPLIED 

CROP  YIELDS:  GRAMS  PER  POT 

Kind 

Amount 

Tobacco 
(Leaves  and 
Stalks) 

Wheat 
(Grain  Only) 

Alfalfa 
Hay 

None       .... 

none 
4.0  grams 
10.5  grams 

4-8 
IO.O 
12-9 

6.8 

9-5 

I2.O 

6.7 

1  1  -5 

IO.2 

Acid  phosphate     .... 
Raw  phosphate     .... 

USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     289 

The  soil  used  in  these  pot  cultures  (which  were  2-gallon  jars) 
was  a  residual  limestone  soil  from  Christian  County,  Kentucky, 
and  contained  870  pounds  of  total  phosphorus  and  32,120  pounds 
of  potassium  in  2  million  pounds  of  surface  soil.  The  results  are 
of  interest;  but,  as  Doctor  Peter  writes,  "  it  must  be  understood 
that  they  are  only  single  experiments  carried  out  one  season,  and 
must  be  valued  accordingly." 

The  Wisconsin  Agricultural  Experiment  Station  (Bulletin  174) 
also  reports  a  single  year's  experiment  with  field  cultures  showing 
that  manure  and  raw  phosphate  increased  the  yield  of  rutabagas 
by  27  per  cent  and  the  yield  of  potatoes  by  47  per  cent  above  the 
yield  from  manure  alone,  and  the  opinion  is  expressed  that  "  these 
results  leave  no  doubt  that  the  use  of  phosphate  supplementing 
manure  is  beneficial." 

In  describing  IVf r.  J.  F.  Jack's  Virginia  farm,  Joseph  E.  Wing, 
the  well-known  agricultural  writer,  makes  the  following  state- 
ments (Breeders'  Gazette,  June  2,  1909) : 

"Proud  as  we  are  of  Woodland  Farm,  I  find  acre  after  acre  of  alfalfa  on  Mr. 
Jack's  farm  as  good  as  our  best.  I  find  it  as  good  as  the  best  that  I  ever  saw 
in  California.  Is  it  all  good?  No.  There  are  acres  that  are  thin,  stunted. 
What  cause  ?  He  is  seeking  that  now.  Doubtless  there  are  areas  that  are  too 
poorly  drained,  there  are  places  yet  sour,  and  some  land  needs  more  feeding. 
No  doubt  at  all  of  that.  He  has  not  limed  liberally  at  all  times.  Last  year,  for 
example,  some  men  told  him  that  they  had  a  prepared  lime  that  was  two  times 
as  effective  as  ordinary  lime.  He  had  been  using  a  ton  to  the  acre ;  he  bought 
this  lime,  at  a  higher  price,  and  used  but  1000  pounds.  Then  he  learned  to  his 
sorrow  that  the  lime  was  simply  slacked  at  the  kilns,  was  so-called  'agricultural 
lime'  and  had  only  about  half  the  strength  of  fresh  burned  lime.  So  it  seems 
sure  that  much  of  his  land  has  had  too  little  lime.  He  finds  that  lime  carbonate, 
that  is,  simply  ground  limestone,  gives  him  as  good  results  as  anything,  and  that 
fortunately  is  cheap." 

""What  an  interesting  thing  it  is  to  find  this  old  Eastern  land  being  newly  dis- 
covered. .  .  .  But  here  the  soil  must  be  fed,  do  not  forget  that !  The  natives 
forgot  it,  hence  their  sorrow  now." 

"Business  methods  apply  to  farming  as  well  as  to  anything  else.  Farming 
is  a  business,  and,  with  present  prices  for  things,  a  paying  business.  It  pays  to 
buy  lime  (Mr.  Jack  is  getting  his  ground  limestone  delivered  to  him  for  $2.90 
this  year)  to  make  land  sweet,  to  buy  phosphorus,  to  sow  legumes,  to  build  soil. 
Alfalfa  is  as  easily  set  in  Virginia  as  in  any  other  state,  and  it  grows  splendidly 
when  the  land  is  made  sweet  with  lime,  filled  with  decaying  vegetable  matter  or 
humus,  given  inoculation  and  phosphorus." 


290 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


"  Alfalfa  will  make  land  in  Virginia  yield  good  returns  on  a  valuation  of  $200 
per  acre,  or  more,  and  land  that  was  worth  $30  per  acre  can  be  set  in  alfalfa 
at  a  cost  of  about  $15  per  acre,  including  lime,  fertilizer,  seed,  and  the  growth 
of  crimson  clover.  Enthusiasm  and  faith,  with  carbonate  of  lime,  phosphorus, 
and  clovers,  can  make  a  land  beautiful  to  the  eye,  inspiring  to  the  soul,  and 
filling  to  the  purse." 

"One  most  valuable  result  seen  here  is  apparently  that  untreated  Tennessee 
phosphate  rock  is  giving  as  good  results  as  phosphorus  in  any  other  form,  using 
not  the  same  amounts,  but  the  same  cost  equivalents.  In  fact,  there  seems  de- 
cided gain  from  the  use  of  the  raw  phosphate." 

This  temporary  superiority  of  raw  phosphate  was  doubtless  due 
to  some  liberation  by  one  green  manuring.  Later  Mr.  Wing  says : 

"The  results  as  they  now  show  are  about  like  this,  speaking  roughly:  Acid 
phosphate  leads  by  far.  Bone  meal  comes  next.  Whether  slag  phosphate  or 
Tennessee  rock  follows  I  do  not  know,  but  both  are  far  in  the  rear  of  either  bone 
meal  or  acid  phosphate."  (Breeder's  Gazette,  Nov.  8,  1911.) 

NOTE.  On  the  author's  Poorland  Farm,  including  about  320  acres  in  the  prairie 
section  of  southern  Illinois  (gray  silt  loam  on  tight  clay),  limestone  is  applied  at  the 
rate  of  2  to  3  tons  per  acre,  and  raw  rock  phosphate  at  the  rate  of  i  ton  per  acre, 
every  six  years.  After  the  phosphorus  content  of  the  plowed  soil  has  been  increased 
from  800  pounds  per  acre  to  about  2000  per  acre,  the  application  of  that  element  will 
probably  be  reduced  to  an  amount  which  will  simply  maintain  the  supply.  Thus 
far  the  use  of  n  car  loads  of  raw  phosphate  and  17  car  loads  of  ground  limestone  has 
given  as  satisfactory  results  as  one  could  reasonably  expect  during  the  first  crop 
rotation.  For  this  special  soil  a  six-year  rotation  is  planned,  as  follows: 

First  year Corn  (and  legume  catch  crop). 

Second  year Part  oats  or  barley,  part  cowpeas  or  soy  beans. 

Third  year Wheat. 

Fourth  year Clover,  or  clover  and  timothy. 

Fifth  year Wheat,  or  clover  and  timothy. 

Sixth  year Clover,  or  clover  and  timothy. 

The  plan  may  be  a  grain  system  where  wheajt  is  grown  the  fifth  year,  only  clover 
seed  being  harvested  the  fourth  and  sixth  years,  or  it  may  be  changed  to  a  live  stock 
system  by  using  a  field  for  pasture  and  meadow  the  last  three  years,  all  manure 
produced  being  applied  to  the  pasture  land  to  be  plowed  under  for  corn.  While 
the  untreated  land  has  produced  about  one  third  of  a  ton  per  acre  of  poor  hay  (part 
timothy  and  redtop,  part  foul  grass,  sorrel,  and  other  weeds),  the  treated  land  has 
produced  more  than  i$  tons  per  acre  of  clean  clover  and  timothy  hay.  A  car  load  of 
limestone  or  phosphate  is  purchased  with  less  hesitation  than  a  cow  or  a  horse,  and 
at  about  the  same  cost. 

A  careful  study  of  the  literature  of  agricultural  science  from 
European  countries  reveals  no  investigations  with  the  use  of  raw 
rock  phosphate  that  compare  in  value  with  those  conducted  by 


USE    OF    PHOSPHORUS   IN   DIFFERENT   FORMS     291 

any  one  of   the  seven  states,    Ohio,  Maryland,   Pennsylvania, 
Rhode  Island,  Maine,  Massachusetts,  or  Illinois. 

There  are  three  essential  points  to  be  kept  in  mind  concerning 
the  use  of  raw  rock  phosphate: 

First,  all  rock  is  not  phosphate  rock,  and  the  farmer  should 
purchase  only  guaranteed  material,  and  he  should  know  how  much 
phosphorus  is  contained  in  the  ground  rock  he  applies  to  the  land, 
if  necessary  by  taking  100  teaspoonfuls  from  100  different  parts 
of  the  car  load  (including  different  depths),  thoroughly  mixing, 
and  sending  half  a  pound  of  this  to  a  reliable  commercial  chemist 
for  analysis. 

Second,  the  rock  should  be  very  finely  ground,  and  it  should  be 
purchased  upon  a  guarantee  that  at  least  90  per  cent  of  it  will  pass 
through  a  sieve  with  100  meshes  to  the  linear  inch  (10,000  meshes 
to  the  square  inch),  which  is  no  finer  than  is  required  for  slag  phos- 
phate. 

Third,  raw  phosphate  should  not  be  expected  to  give  marked 
benefits  except  when  used  in  connection  with  adequate  supplies 
of  decaying  organic  matter.  It  has  practically  no  value  as  a  top 
dressing,  but  must  be  plowed  under  and  thoroughly  incorporated 
with  the  soil  where  the  roots  feed.  Of  course,  it  will  supply  only 
the  element  phosphorus,  and  will  not  take  the  place  of  any  other 
deficient  element,  nor  act  as  a  soil  stimulant  to  liberate  other  plant 
food  from  the  soil,  although  it  sometimes  contains  small  amounts 
of  carbonate,  and  then  has  some  tendency  to  correct  soil  acidity, 
but  in  this  it  is  insignificant  compared  to  the  effect  of  ground 
limestone. 

The  following  interesting  discussion  concerning  the  use  of  raw 
rock  phosphate,  from  the  viewpoint  of  the  fertilizer  manufacturer, 
was  published  in  pamphlet  form  and  widely  disseminated  in  1908, 
by  the  National  Fertilizer  Association.  It  was  also  published  in 
full  in  the  American  Fertilizer,  August,  1908,  and  in  part  in  Ar- 
mour's Farmer's  Almanac  for  1909.  It  is  reproduced  in  complete 
form  in  the  following  pages,  because  it  deserves  to  be  read  by  every 
careful  student  of  soil  fertility.  Its  cautions  against  the  use  of 
raw  phosphate  as  a  source  of  immediately  available  plant  food  are 
commended.  It  also  serves  to  emphasize  the  fact  stated  in  the 
introduction,  that,  "  if  the  independent  farmer  is  to  adopt  and 


292        SYSTEMS    OF   PERMANENT   AGRICULTURE 

maintain  permanent  systems  of  profitable  agriculture,  he  cannot 
accept  '  parrot '  instruction,"  not  even  when  offered  by  the  fer- 
tilizer agent. 

The  fact  that  acid  phosphate  and  "  2-8-2  "  fertilizers  are  still 
used  in  the  Eastern  and  Southern  states,  largely  as  soil  stimulants 
and  for  a  single  crop,  or  for  one  year's  effect  only,  fairly  raises  the 
question  whether  agricultural  practice  in  those  states  is  not  influ- 
enced more  by  the  "arguments"  of  the  fertilizer  agent  than  by  the 
established  facts  and  principles  from  the  experiment  stations. 

RAW  ROCK  PHOSPHATE,  "FLOATS" 

PUBLISHED  BY 
THE  NATIONAL  FERTILIZER  ASSOCIATION 

For  years  the  raw  rock  question  has  cropped  out  spasmodically,  in  different 
parts  of  the  world,  like  the  measles  or  some  other  affliction. 

Sometimes  it  was  the  result  of  the  recommendation  of  some  impractical 
theorist  who  occupied  a  position  that  brought  him  before  the  farmer  —  oftener 
it  was  foisted  on  an  unsuspecting  farming  community  by  some  one  who  was 
either  directly  or  indirectly  interested  in  an  offgrade  phosphate  mine,  and  who 
used  his  official  position  to  further  the  interests  of  the  rock  mine  at  the  expense 
of  the  farmer. 

But  no  matter  what  started  its  use,  the  result  has  always  been  the  same  —  no 
benefit  derived  from  its  use  —  a  distrust  of  legitimate  fertilizers,  and  a  distinct 
set-back  to  agricultural  interests  which  has  taken  several  years  to  overcome. 

In  the  following  pages  we  give  you  the  opinions  of  foreign  experiment  station 
men  as  well  as  those  of  our  own  country. 

Both  statistics  and  your  good  common  sense  tell  you  that  the  older  the  state 
or  country,  the  more  fertilizers  are  used  and  the  greater  the  knowledge  they 
have  of  their  use. 

The  mere  fact  that  in  these  older  communities,  both  abroad  and  in  this 
country,  the  use  of  legitimate  fertilizers  has  increased  rapidly  from  year  to  year 
for  a  hundred  years  conclusively  shows  their  value. 

The  fact  that  wherever  raw  rock  has  been  used,  its  use  has  been  abandoned, 
shows  its  worthlessness. 

Read  what  authorities  who  know  have  to  say  on  this  subject. 

RESOLUTION  passed  by  the  Association  of  German  Agricultural  Experiment 
Stations,  in  congress  assembled,  September  14,  1907,  at  Dresden,  Germany: 

"As  a  result  of  the  extensive  advertising  which  is  done  by  certain  parties  ad- 
vocating the  use  of  RAW  ROCK  PHOSPHATE,  the  association  passed  the  follow- 
ing resolution: 

"THE  ASSOCIATION  HAS  CONCLUDED,  FROM  FERTILIZER  EXPERIMENTS  AT 
HAND  WITH  RAW  PHOSPHATE  FERTILIZER,  THAT  THERE  IS  SHOWN  NO  PROFIT- 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS      293 

ABLE  FERTILIZER  EFFECT,  APART  FROM  THOSE  OF  ACID  SOIL.  IN  CONSEQUENCE 
THEREOF  THE  ASSOCIATION  FEELS  IT  SHOULD  DISCOURAGE  THE  USE  OF  RAW 
PHOSPHATE  ON  OTHER  SOILS." 

See  6;th  Volume  (5-6),  page  329,  "  LANDWIRTSCHAFTLICHER  VERSUCHS 

STATION." 

The  Association  of  German  Agricultural  Experiment  Stations  represents  the 
highest  authority  on  agricultural  matters  in  Germany,  and  undoubtedly  the  best 
in  the  world. 

German  investigators,  particularly  Dr.  Von  Liebig,  were  the  authors  of  most 
of  the  fundamental  principles  underlying  fertilization  and  agriculture,  —  and 
it  is  to  them  that  we  largely  owe  the  progress  made  in  this  direction. 

In  view  of  the  well-known  thoroughness  of  German  agricultural  investigators, 
and  the  fact  that  the  Association  of  German  Agricultural  Experiment  Stations 
is  universally  regarded  as  the  world's  highest  authority  on  such  matters,  their 
opinion  on  the  use  of  RAW  PHOSPHATE  as  a  fertilizer  is  of  great  importance  to 
the  American  farmer. 

On  account  of  the  high  price  of  land  in  Germany  intensive  farming  is  every- 
where practiced.  The  farmers  must,  of  necessity,  use  fertilizer  containing 
plant  food  in  available  condition.  Their  selection  of  fertilizers  is  based  on  in- 
numerable experiments  covering  over  a  hundred  years. 

The  difference  in  crop  yields  per  acre  in  Germany  as  compared  with  the 
United  States  is  conclusive  evidence  of  the  soundness  of  their  methods  of 
fertilization.  The  average  wheat  yield  per  acre  in  Germany  for  the  ten  years 
1895  to  1904,  inclusive,  was  27.2  bushels,  as  compared  with  13.4  bushels  in  the 
United  States  for  the  same  period.  On  oats  the  yield  per  acre  in  Germany  was 
46.0  bushels,  as  compared  with  29.2  bushels  in  the  United  States  for  the  same 
period.  (See  pages  671  and  678,  "Statistical  Matter,"  reprint  from  Year  Book 
of  Department  of  Agriculture  for  1905.) 1 

The  soils  of  Germany  have  been  cropped  for  hundreds  of  years,  while  a  large 
portion  of  those  in  this  country  are  virgin  or  comparatively  fresh.  Proper 
fertilization  is  the  secret  of  the  higher  yield  per  acre  in  Germany.  If  the  United 
States  is  to  maintain  its  supremacy  in  agriculture,  farmers  in  this  country  will 
have  to  properly  fertilize  their  crops,  —  and  they  can  well  take  heed  to  the 
experience  of  their  German  brothers  in  this  respect. 

Before  using  raw  rock,  therefore,  you  would  do  well  to  ascertain  its  true 
fertilizing  value  —  the  availability  of  the  plant  food  it  is  supposed  to  contain  — 
and  especially  to  consider  the  decision  of  the  German  experimenters  after  years 
of  careful  testing. 

From  the  standpoint  of  furnishing  available  plant  food,  RAW  ROCK  PHOS- 
PHATE is  not  a  fertilizer.  The  report  of  the  twenty-fourth  annual  meeting  of 
the  Association  of  German  Agricultural  Experiment  Stations,  at  which  the 

1  The  ten-year  average  yield  of  corn  in  the  great  state  of  Georgia,  where  more 
manufactured  acidulated  commercial  fertilizers  are  used  than  in  any  other  state, 
is  ii  bushels  per  acre.  —  C.  G.  H. 


294       SYSTEMS    OF   PERMANENT   AGRICULTURE 

resolution  quoted  was  passed,  states  that  from  "real  exact  experiments,"  con- 
ducted by  such  authorities  as  P.  Wagner,  Tacke,  Bottcher,  Lemmerman  and 
others,  "but  little  fertilizing  effect  was  shown." 

Further  experiments  made  by  Czerhati,  L.  Rey,  Clausen,  and  others,  led  to 
similar  results  just  stated. 

The  same  report  states  that,  "From  the  present  experiments  it  can  be  con- 
cluded with  certainty  that  the  general  use  of  earthly  phosphates  (RAW  ROCK 
PHOSPHATE)  cannot  be  considered  as  phosphoric  acid  fertilization."  Phos- 
phoric acid  is  the  only  element  this  material  contains,  and  if  IT  is  NOT  available 
it  is  useless  for  fertilizing  purposes. 

The  experiment  station  officials  of  Germany  have  gone  on  record  against  the 
use  of  RAW  ROCK  PHOSPHATE  in  no  uncertain  tone.  Their  opinion  is  shared, 
with  but  one  or  two  exceptions,  by  all  the  experiment  stations  in  this  country. 
If  THIS  material  cannot  be  recommended  for  German  soils,  where  proper 
fertilization  has  been  studied  for  so  many  years,  is  it  not  folly  to  attempt  its  use 
on  the  comparatively  fresh  soils  of  this  country  ? 

This  report  also  refers  to  some  recent  experiments  conducted  by  parties  en- 
deavoring to  promote  the  sale  of  raw  rock  phosphate  in  Europe.  In  comment- 
ing on  the  so-called  tests  or  experiments,  the  German  report  states  —  that  they 
"were  carried  out  with  but  very  little  exactness."  They  further  class  these 
experiments  as  "entirely  unfounded,  have  been  rejected  by  scientific  agricul- 
turists, and  especially  by  Wagner,  Tacke,  and  Bottcher,  in  a  manner  not  to  be 
misunderstood." 

The  said  representations  of  these  promoters  are  classed  as  "A  very  serious 
deception,"  and  misleading  to  the  farmers. 

The  efforts  to  promote  the  sale  of  RAW  ROCK  PHOSPHATE  in  this  country  — 
in  the  light  of  world-wide  failure  to  show  any  appreciable  fertilizing  effect  — 
can  only  be  classed,  in  the  language  of  the  German  experimenters,  as  "a  very 
serious  deception,"  and  misleading  to  the  farmers. 

Not  alone  in  Germany  have  experiments  with  RAW  ROCK  PHOSPHATE  proven 
very  unsatisfactory.  Professor  F.  H.  Storer,  in  Volume  I  of  his  book  "Agri- 
culture," in  speaking  of  the  value  of  raw  phosphate  USED  IN  CONNECTION 
WITH  MANURE,  as  compared  with  superphosphate,  says:  "This  question  would 
seem  to  have  been  answered  long  ago,  in  so  far  as  good  land  is  concerned,  by  the 
common  English  practice  of  using  superphosphates." 

Again,  later,  in  comparing  the  effects  of  the  same  materials  for  fertilizing 
purposes  in  European  countries,  he  says:  "For  Europe  at  least,  i.e.,  for  fertile 
districts,  the  question  has  been  decided  fully  long  ago  and  most  emphatically 
in  favor  of  superphosphate.  It  has  been  decided  by  the  long-continued  experi- 
ments of  a  multitude  of  farmers,  and  their  conclusion  has  been  plainly  expressed 
by  the  ever  increasing  demand  for  superphosphate."  l 

1  Director  Hall  of  Rothamsted,  in  his  "  Fertilizers  and  Manures  "  (1909),  .page 
118,  says:  "The  mineral  phosphates  have  been  but  little  employed  directly  as 
manures,  though  there  is  plenty  of  evidence  that  when  they  are  really  finely 
ground,  they  are  effective  enough  on  soils  retaining  plenty  of  water."  —  C.  G.  H. 


USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     295 

Coming  down  to  our  country,  we  find  that  experiments  with  RAW  ROCK 
PHOSPHATE  —  with  scarcely  any  exception  —  have  proven  unsatisfactory. 
Experiments  conducted  by  the  Maine  Experiment  Station,  covering  several 
years  on  various  crops,  designed  to  show  the  relative  availability  of  phosphoric 
acid  as  supplied  in  acid  phosphate,  floats  (raw  rock  phosphate),  and  redonda 
phosphate,  were  summarized  as  follows : 

"In  every  case  the  acid  rock  (Acid  Phosphate)  gave  the  best  returns.  The 
gain  was  especially  marked  with  the  family  Gramineae,  three  members  of  which 
(barley,  corn,  and  oats)  yielded  nearly  double  the  amount  produced  by  the 
Floats  or  Redonda.  The  effect  upon  sunflowers  and  buckwheat  was  equally 
marked.  If  we  compare  the  amount  of  dry  matter  produced  by  the  acid  rock 
with  that  produced  by  the  Floats  for  all  crops  grown,  we  find  the  balance  in 
favor  of  the  acid  rock  to  be  FIFTY -TWO  PER  CENT.  In  other  words,  the  effect  of 
the  available  phosphoric  acid  as  compared  with  the  insoluble  phosphate  was  to 
increase  the  product  MORE  THAN  ONE  HALF."  1 

The  Georgia  Experiment  Station,  commenting  in  Bulletin  No.  2,  concern- 
ing field  experiments  with  phosphates  and  kainit  applied  to  cotton,  states: 
"  Of  phosphates,  Acid  Phosphate  appears  to  lead,  slag  comes  next,  and  the 

FLOATS   ARE   LAST."  2 

A  later  Georgia  Bulletin  (No.  31),  in  reviewing  a  comparison  of  superphos- 
phate with  Tennessee  soft  phosphate,  states :  "Superphosphate  in  a  complete 
fertilizer  was  compared  with  one,  one  and  a  half  and  two  times  the  same  amount 
of  Tennessee  soft  phosphate.  The  latter  (Tennessee  soft  phosphate)  was  ap- 
plied in  each  case  at  a  loss."  2 

In  the  Annual  Massachusetts  Experiment  Station  Report  for  1902,  concern- 
ing an  experiment  with  various  kinds  of  phosphates  which  were  applied  in 
equal  amounts  of  phosphoric  acid,  there  is  the  following  regarding  raw  rock 
phosphate :  "Tennessee  phosphate  and  Florida  soft  phosphate  gave  results  very 
much  inferior  to  all  the  others."  This  was  an  experiment  on  onions. 

In  the  Massachusetts  Annual  Report  for  the  following  year  (1903),  concern- 
ing the  same  experiment  continued  on  cabbages,  the  previous  year's  results  are 
confirmed:  "That  Tennessee  phosphate  and  Florida  soft  phosphate  proved 
very  much  inferior  to  all  others." 3 

1  This  quotation  is  taken  from  page  72  of  the  1898  Report  of  the  Maine  Experi- 
ment Station;   while  on  page  57  of  the  1900  Report  occur  the  following  statements: 
"  For  the  first  year  the  largest  increase  of  crop  was  produced  by  soluble  phosphoric 
acid.    For  the  second  and  third  years,  without  further  addition  of  fertilizers,  better 
results  were  obtained  from  the  plots  where  stable  manure  and  insoluble  phosphates 
were  used."  —  C.  G.  H. 

2  These  are  single-year  tests.   The  following  quotation  might  also  be  made  from 
page  161  of  Georgia  Bulletin  No.  25  :  "Florida  Soft  Phosphate  appears  to  be  equally 
as  valuable  as  Acid  Phosphate,  the  difference,  if  any,  being  rather  in  its  favor. "  — 
C.  G.  H. 

3  On  the  other  hand,  the  South  Carolina  raw  rock  phosphate  produced  a  much 
larger  yield  than  acid  phosphate,  especially  of  marketable  cabbage,  as  shown  in 
Table  49. —  C.G.  H. 


296       SYSTEMS    OF   PERMANENT  AGRICULTURE 

In  Scott  County,  Indiana,  an  experiment  to  determine  the  relative  value  of 
raw  rock  phosphate  and  acid  phosphate  was  started  in  1904  and  continued  for 
four  years.  Equal  values  of  rock  phosphate  and  acid  phosphate  were  ap- 
plied in  ONE  application  the  first  year  —  corn  and  wheat  alternating.  The 
actual  amount  of  plant  food  applied  was  286  pounds  of  total  phosphoric  acid 
in  the  rock  phosphate  and  100  pounds  phosphoric  acid  in  the  acid  phosphate. 
There  were  three  plots  in  the  experiment  —  one  fertilized  with  rock  phosphate, 
one  with  acid  phosphate,  one  unfertilized.  Notwithstanding  the  fact  that  the 
first  year's  corn  crop  was  a  total  failure  on  all  plots,  the  results  on  wheat  showed 
a  gain  of  fourteen  bushels  per  acre  with  acid  phosphate  as  against  only  nine 
bushels  for  the  rock  phosphate  over  the  unfertilized  plot.  The  profit  per  acre 
in  four  years  from  rock  phosphate  was  $11.55;  *  the  profit  in  four  years  from 
acid  phosphate  was  $13.50. 

In  Marion  County,  Indiana,  another  experiment  for  the  same  purpose  was 
started,  and  crops  harvested  for  two  years?  Only  one  application  of  fertilizer 
was  made,  the  entire  amount  being  applied  the  first  season.  As  in  Scott  County, 
equal  values  of  rock  phosphate  and  acid  phosphate  were  applied.  The  results 
speak  for  themselves,  and  they  are  given  in  the  table  below  as  taken  from 
Circular  No.  10  of  the  Indiana  Experiment  Station.  The  yields  are  given  in 
bushels  per  acre: 

CORN          WHEAT 

Amount  per  acre J9O4  1905 

Unfertilized 20  3 

Rock  phosphate,  1000  Ib 20  6 

Acid  phosphate,  715  Ib 27  16 

The  value  of  the  increase  per  acre,  figuring  corn  at  35  cents 
and  wheat  at  80  cents  per  bushel,  on  the  plot  fertilized  with 

acid  phosphate,  was $12.85 

Deducting  cost  of  acid  phosphate 5.00 

Net  return  on  the  increase $7.85 

Value  of  the  increase  with  rock  phosphate    .     .     .     .  '  .     .         2.40 

Deducting  cost  of  rock  phosphate 5.00 

Or  a  net  loss  of $2.60  per  acre 

On  the  total  yields  the  results  were  as  follows: 

Unfertilized $9.40  per  acre 

8  Raw  rock  phosphate 6.80  per  acre 

3  Acid  phosphate 17.25  per  acre 

1  This  is  a  very  fair  profit  considering  that  about  two  thirds  of  the  raw  rock 
phosphate  will  remain  in  the  soil  after  the  acid  phosphate  is  completely  exhausted. 
It  should  also  be  noted  that  the  cost  of  the  acid  phosphate  was  figured  at  $14  per 
ton,  and  the  cost  of  the  raw  phosphate  at  $10  per  ton.  —  C.  G.  H. 

3  Italics  mine.  —  C.  G.  H. 

1  Cost  of  rock  phosphate  and  acid  phosphate  deducted. 


USE    OF   PHOSPHORUS   IN   DIFFERENT   FORMS     297 

These  figures  show  that  the  rock  phosphate  was  applied  at  a  dead  loss  of 
$2.60  per  acre  —  the  unfertilized  yield  value  being  $2.60  per  acre  more  than  the 
rock  phosphate.  The  yield  with  acid  phosphate  was  $7.85  more  than  the 
UNFERTILIZED,  and  $10.45  Per  acre  niore  than  the  RAW  ROCK  PHOSPHATE. 
These  results  are  from  experiments  primarily  intended  to  show  the  value  of  raw 
rock  as  a  fertilizer.  They  are  self-explanatory,  and  show  conclusively  the  FOLLY 
OF  CONSIDERING  THIS  MATERIAL  AS  A  FERTILIZER.  Further,  these  results  were 
obtained  from  100  pounds  of  phosphoric  acid  in  acid  phosphate  as  compared 
with  286  pounds  of  raw  rock  phosphate. 

The  practical  farmer,  interested  in  the  proper  use  of  commercial  fertilizers, 
can  easily  figure  that  where  acid  phosphate  gave  such  remarkable  returns  on 
experiments  covering  a  series  of  years,  it  will  pay  him  a  handsome  profit  to 
invest  judiciously  in  fertilizers  every  year  giving  such  good  returns. 

Tennessee  has  some  of  the  largest  phosphate  deposits  in  the  world.  In  this 
state  where  the  value  of  phosphate  is  so  well  understood,  Professor  C.  A. 
Mooers,  chemist  and  agronomist  of  the  Agricultural  Experiment  Station  at 
Knoxville,  in  a  recent  letter  to  THE  AMERICAN  FERTILIZER  has  the  following  to 
say  with  regard  to  the  use  of  this  material  in  its  crude  state : 

"A  bill  was  introduced  in  the  Legislature,  just  adjourned,  to  allow  the  sale 
of  ground  rock  phosphate  as  a  fertilizer.  In  presenting  this  matter  to  the 
Agricultural  Committee,  the  Commissioner  of  Agriculture  and  myself  took  the 
position  that  it  would  not  be  desirable  to  tag  this  material,  as  that  would,  to  a 
certain  extent,  stamp  it  with  the  State's  approval.  Our  position  is  better  under- 
stood when  it  is  considered  that  a  very  large  part  of  the  fertilizers  used  in  this 
State  are  for  wheat,  and,  as  is  well  known,  RAW  PHOSPHATE  ROCK,  as  ordinarily 
used,  GIVES  NO  RETURNS  ON  THIS  CROP.  Other  large  amounts  are  used,  es- 
pecially in  West  Tennessee,  by  the  truckers,  and  for  garden  crops  also  RAW 
PHOSPHATE  WOULD  BE  INADVISABLE.  Fertilizers  have  been  used  in  this  State 
for  many  years,  but  our  farmers  have  not  studied  the  matter  to  any  great  ex- 
tent, so  that  many  of  them  would  buy  a  fertilizer  just  BECAUSE  IT  WAS  CHEAP, 
especially  if  it  had  the  State's  tag  on  it. 

"Our  results  on  leguminous  crops,  which  are  supposed  to  be  better  able  to 
make  use  of  the  so-called  insoluble  forms  of  phosphoric  acid  than  others,  do  not 
warrant  the  general  use  of  RAW  PHOSPHATE.  I  have  recently  corresponded 
with  a  number  of  station  men  who  are  interested  in  the  use  of  fertilizers,  and  I 
find  that  the  general  opinion  is  AGAINST  THE  USE  OF  THIS  MATERIAL,  although 
under  special  conditions,  such  as  are  found  on  a  decidedly  acid  soil,  its  use  may 
be  advisable." 

The  state  of  Alabama  is  one  of  the  oldest  of  the  states  using  commercial 
fertilizers.  Bulletin  No.  24,  issued  May  15,  1908,  contains  an  article  on  "Raw 
Phosphate  Rock  as  a  Fertilizer."  Following  are  extracts  from  this  article: 

"Many  parties  have  written  to  this  office  for  information  as  to  the  relative 
fertilizing  value  of  the  raw  phosphate,  as  compared  with  the  acidulated  phos- 
phates, and  the  writer  has  invariably  advised  caution  in  the  employment  of  this 
particular  kind  of  phosphate. 


298        SYSTEMS    OF   PERMANENT   AGRICULTURE 

"The  samples  of  this  material  which  have  reached  this  laboratory  have  al- 
most invariably  exhibited  a  poor  mechanical  condition,  the  particles  being 
coarse  and  irregular  in  size.  As  the  fineness  of  division  of  this  phosphate  has  a 
most  important  influence  upon  its  availability  to  the  plant,  purchasers  of  this 
material  have  been  advised  to  only  use  the  rock  which  has  been  pulverized  to  a 
state  of  practical  impalpability,  the  material  in  this  condition  being  commonly 
designated  by  the  name  of  'floats.' 

"A  typical  analysis  of  the  raw  phosphate  rock  sent  to  this  laboratory  this 
season  is  given  herewith : 

Citrate-soluble  phosphoric  acid 0.68  per  cent 

Acid-soluble  phosphoric  acid 23-55  Per  cent 

Total  phosphoric  acid 24.23  per  cent 

"It  will  be  noted  that  nearly  all  of  the  phosphoric  acid  in  this  phosphate  is  in 
an  insoluble  or  acid-soluble  condition,  and  there  is  SCARCELY  A  TRACE  OF  WATER 

SOLUBLE  PHOSPHORIC  ACID  TO  BE  FOUND  IN  THIS  RAW  PHOSPHATE. 

"With  regard  to  the  comparative  availability  of  raw  phosphate  rock,  it  might 
be  stated  that  the  Experiment  Station  at  Auburn  has,  during  the  past  few  years, 
carried  out  under  its  supervision  more  than  one  hundred  cooperative  soil  and 
crop  tests  in  a  great  many  different  localities  in  the  State  with  a  view  to  deter- 
mining the  comparative  efficiency  of  raw  phosphate  and  acid  phosphate  for  fer- 
tilizing purposes.  These  tests  have  been  carried  out  upon  quite  a  variety  of 
soils,  and  upon  most  soils  the  RAW  PHOSPHATE  HAS  FAILED  TO  GIVE  ANYTHING 

LIKE  AS  GOOD  RESULTS  AS  THE  ACID  PHOSPHATE. 

"In  the  case  of  acid  phosphate,  the  ready  solubility  of  most  of  the  phos- 
phoric acid  contained  therein  promotes  its  rapid  and  thorough  distribution 
through  the  top  layer  of  the  soil,  and  hence  the  plant  food  is  so  well  dissemi- 
nated that  it  is  brought  within  easy  reach  of  the  root  system  of  the  plant, 
whereas  in  the  case  of  the  crude  insoluble  phosphate  the  diffusion  and  dis- 
tribution of  the  phosphoric  acid  is  necessarily  slow,  and  much  of  the  phos- 
phate is  left  unutilized  at  the  end  of  the  season  in  which  it  is  applied. 

"For  the  above  reasons  IT  is  DEEMED  INADVISABLE  TO  EMPLOY  THE  CRUDE 
PHOSPHATE  to  any  great  extent  upon  any  given  soil  until  comparative  tests  of 
the  crude  rock  and  acid  phosphate  have  been  made  upon  that  soil,  and,  even 
under  these  conditions,  it  will-  probably  be  found  necessary  to  use  much  larger 
amounts  of  phosphate  rock  than  are  ordinarily  employed  to  secure  a  satis- 
factory return  from  its  application." 

While  the  experience  of  the  German  Experiment  Stations,  combined  with  a 
majority  in  this  country,  show  emphatically  that  raw  rock  phosphate  has 
little  or  no  fertilizing  value,  in  addition  the  method  of  applying  followed  by 
users  of  this  material  in  this  country  is  MOST  EXTRAVAGANT  AND  WASTEFUL. 
The  method  followed  would  soon  exhaust  the  known  or  visible  supply  of 
phosphate  rock.  Further,  the  enormous  quantities  necessary  to  apply  per  acre, 
instead  of  being  scattered  over  and  benefiting  millions  of  acres,  would  be  wasted 
on  comparatively  few. 


USE   OF   PHOSPHORUS   IN   DIFFERENT   FORMS 


299 


On  the  other  hand,  this  crude  material,  when  properly  treated  with  sulfuric 
acid  and  converted  into  acid  phosphate,  to  be  used  either  as  straight  acid 
phosphate  or  in  mixed  fertilizers,  becomes  a  source  of  available  plant  food  of 
greatest  value.  Raw  rock  phosphate,  as  mined  and  sold  by  certain  operators, 
does  not  contain  plant  food  immediately  available  to  growing  crops.  It  is  only 
by  proper  handling  and  treatment  with  sulfuric  acid  that  this  material  is  con- 
verted into  fertilizer  furnishing  plant  food  available  to  various  crops  and  soils. 

Reputable  fertilizer  manufacturers  decry  the  use  of  raw  rock  phosphate  as 
a  fertilizer,  knowing  that  it  will  NOT  prove  satisfactory,  as  borne  out  by  exten- 
sive experiments  of  the  world's  best  agriculturists.  They  have  gone  on  record 
against  its  use,  and  any  lack  of  results  on  the  part  of  those  using  this  material 
should  not  vitiate  against  the  use  of  commercial  fertilizers  rightly  prepared, 
furnishing  available,  nourishing  plant  food  for  all  crops. 

(Signed).  THE  NATIONAL  FERTILIZER  ASSOCIATION. 

The  author  feels  that  no  further  comment  is  necessary  regarding 
this  statement  from  the  National  Fertilizer  Association.  The 
facts  are  presented  in  very  complete  form  in  the  preceding  pages, 
and  the  reader  must  draw  his  own  conclusions.  For  other  illustra- 
tions of  the  possibility  of  erroneous  conclusions  being  drawn  by 
such  German  investigators  as  advance  theories  or  reach  conclu- 
sions without  sufficient  facts,  reference  may  be  made  to  Chapter 
31,  and  also  to  Sir  Henry  Gilbert's  very  interesting  and  complete 
discussion  of  the  sources  of  fat  in  the  animal  body,  based  upon 
Rothamsted  investigations  in  which  327  different  animals  were 
dissected,  10  different  selected  carcasses  having  been  subjected  to 
chemical  analysis,  following  the  analysis  of  the  foodstuffs  provided 
during  long  feeding  periods.  (See  Office  of  Expt.  Stations  Bui.  22.) 

OHIO  EXPERIMENTS  WITH  MANURE  AND  PHOSPHATES,  1897-1911 


VALUE  OF  THREE 

CORN,1 

CORN, 

WHEAT, 

HAY, 

CROPS 

Son.  TREATMENT 

15-YEAR 

AVERAGE 

14-  YEAR 
AVERAGE 

1  4-  YEAR 

AVERAGE 

II-YEAR 
AVERAGE 

1909  Corn 

1  909  Corn 

(Bushels) 

(Bushels) 

(Bushels) 

(Tons) 

Excluded 

Included 

None    

33-0 

34-4 

II.  2 

1.30 

$27.68 

$27.19 

Manure  alone    .... 

54-6 

56.0 

2I.O 

1.80 

45.10 

44.61 

Manure,  rock  phosphate 

62.4 

62.5 

25-7 

2.28 

53-54 

53-51 

Manure,  acid  phosphate 

62.0 

63.8 

26.1 

2.25 

54-iQ 

53-47 

1  Because  of  irregular  insect  injury,  the  Ohio  Station  prefers  not  to  include  the 
1909  corn  crop  in  the  general  average.     (For'details,  see  pages  245  to  258.) 


CHAPTER  XVIII 

THEORIES   CONCERNING    SOIL   FERTILITY 

ABOUT  three  hundred  years  ago  Van  Helmont,  a  Flemish  alche- 
mist, planted  a  five-pound  willow  tree  in  200  pounds  of  dry  soil. ' 
He  watered  it  with  rain  water  for  five  years,  and  then  found  that 
the  tree  had  gained  164  pounds  and  that  the  soil  had  lost  only 
2  ounces,  in  weight.  Therefore,  he  concluded,  water  is  the  source 
of  plant  food.  While  it  seemed  to  him  that  his  evidence  was  strong 
and  positive,  all  know  now  that  his  conclusion  was  wrong,  and  that 
the  air,  the  water,  and  the  soil  are  all  essential  sources  of  plant  food. 

It  will  be  noted  that  2  ounces  removed  from  the  200  pounds  of 
soil  correspond  to  1250  pounds  from  2  million  pounds  of  soil. 

Later,  Bradley,  in  his  "  General  Treatise  of  Husbandry  and 
Gardening,"  argued  that  water  could  be  distilled  or  evaporated, 
which  was  not  the  case  with  willow  trees;  and,  hence,  that  water 
is  not  the  food  of  plants.  He  held  that  air  must  be  the  food  of 
plants. 

About  two  hundred  years  ago,  Jethro  Tull,  the  inventor  of  the 
first  seed  drill,  taught  that  neither  water  nor  air  could  be  the  food 
of  plants  because  they  were  furnished  alike  to  all  plants;  whereas, 
two  adjoining  fields  produced  very  different  yields  because  one 
was  impoverished  soil  while  the  other  had  been  enriched.  Tull 
wrote  as  follows: 

"It  is  agreed  that  all  the  following  materials  contribute  in  some  manner  to 
the  increase  of  plants,  but  it  is  disputed  which  of  them  is  that  very  increase  of 
food:  (i)  Niter,  (2)  Water,  (3)  Air,  (4)  Fire,  (5)  Earth.  .  .  . 

"  Niter  is  useful  to  divide  and  prepare  the  food,  and  may  be  said  to  nourish 
vegetables  in  much  the  same  manner  as  my  knife  nourishes  me,  by  cutting  and 
dividing  my  meat;  but  when  niter  is  applied  to  the  root  of  a  plant,  it  will  kill 
it  as  certainly  as  a  knife  misapplied  will  kill  a  man ;  which  proves  that  niter  is, 
in  respect  of  nourishment,  just  as  much  the  food  of  plants,  as  white  arsenic  is 
the  food  of  rats,  and  the  same  may  be  said  of  salts. 

300 


THEORIES    CONCERNING   SOIL   FERTILITY        301 

"Water,  from  Van  Helmont's  experiment,  was  by  some  great  philosophers 
thought  to  be  it.  But  these  were  deceived,  in  not  observing  that  water  has 
always  in  its  intervals  a  charge  of  earth,  from  which  no  art  can  free  it. 

"  Air,  because  its  spring,  etc.,  is  as  necessary  to  the  life  of  vegetables  as  the 
vehicle  of  water  is,  some  modern  virtuosi  have  affirmed,  from  the  same  and 
worse  arguments  than  those  of  the  water  philosophers,  that  air  is  the  food  of 
plants.  .  .  . 

"Fire.  No  plant  can  live  without  heat,  though  different  degrees  of  it  be 
necessary  to  different  sorts  of  plants.  Some  are  almost  capable  of  keeping 
company  with  the  salamander,  and  do  live  in  the  hottest  exposures  of  the  hot 
countries.  Others  have  their  abode  with  fishes  under  water,  in  cold  climates; 
for  the  sun  has  his  influence,  though  weaker,  upon  the  earth  covered  with 
water,  at  a  considerable  depth,  Which  appears  by  the  effect  the  vicissitudes  of 
winter  and  summer  have  upon  the  subterraqueous  vegetables. 

"  But  that  fire  is  the  food  of  plants,  I  do  not  know  any  author  has  affirmed, 
except  Mr.  Lawrence,  who  says:  'They  are  true  fire-eaters';  and  even  he  does 
not  seem  to  intend  that  this  expression  of  his  should  be  taken  literally." 

"Earth.     That  which  nourishes  and  augments  a  plant,  is  the  true  food  of  it. 

"Every  plant  is  earth,  and  the  growth  and  true  increase  of  a  plant  is  the 
addition  of  more  earth." 

"Too  much  earth,  or  too  fine,  can  never  possibly  be  given  to  roots  .  .  .  and 
earth  is  so  surely  the  food  of  all  plants,  that  with  the  proper  share  of  the  other 
elements,  which  each  species  of  plants  requires,  I  do  not  find  but  that  any 
common  earth  will  nourish  any  plant." 

"The  mouths,  or  lacteals,  being  situate,  and  opening  in  the  convex  super- 
ficies of  roots,  they  take  their  pabulum,  being  fine  particles  of  earth,  from  the 
superficies  of  the  pores,  or  cavities,  wherein  the  roots  are  included.  .  .  .  These 
particles,  which  are  the  pabulum  of  plants,  are  so  very  minute  and  light,  as  not 
to  be  singly  attracted  to  the  earth,  if  separated  from  those  parts  to  which  they 
adhere,  or  with  which  they  are  in  contact  (like  dust  to  a  looking  glass,  turn  it 
upwards,  or  downwards,  it  will  remain  affixed  to  it),  as  these  particles  do  to 
those  parts,  until  from  thence  removed  by  some  agent. 

"A  plant  cannot  separate  these  particles  from  the  parts  to  which  they  adhere, 
without  the  assistance  of  water,  which  helps  to  loosen  them. 

"As  to  the  fineness  of  the  pabulum  of  plants,  it  is  not  unlikely  that  roots  may 
insume  no  grosser  particles  than  those  on  which  the  colors  of  bodies  depend; 
but  to  discover  the  greatness  of  those  corpuscles,  Sir  Isaac  Newton  thinks,  will 
require  a  microscope  that  with  sufficient  distinctness  can  represent  objects  five 
or  six  hundred  times  bigger  than  at  a  foot  distance  they  appear  to  the  naked  I 
eye." 

In  general,  Jethro  Tull  taught  that  the  soil  particles  are  the  food   • 
(pabulum)  of  plants,  and  that,  if  the  soil  were  made  sufficiently 
fine  by  cultivation,  the  plants  could  then  absorb  these  fine  particles 
of  earth  and  produce  large  crops  continuously.   In  answer  to  the 


302 

arguments  of  his  critics  that  the  agricultural  practice  of  his  time 
was  the  result  of  long  experience  and  consequently  must  be  cor- 
rect, he  expressed  a  fundamental  truth  in  the  following  words: 

"The  experience  of  1700  years  no  more  proves  this  practice  to  be  right, 
than  the  long  experience  of  cattle  drawing  by  their  tails  proved  that  practice 
right,  before  drawing  by  traces  was  by  experiment  proved  to  be  better:  for 
nothing  can  be  depended  on  as  experience,  which  has  not  been  tried  by  experi- 
ment." 

He  also  classes  himself  with  those  who  "  cannot  believe  that  a 
man  will  become  bald  by  being  shaved  at  the  wrong  time  of  the 
moon,  without  more  experience  than 'has  been  made  for  it  these 
1700  years  past/)  - 

Another  century  passed,  during  which  the  humus  theory  ad- 
vanced by  Thaer  and  others  gained  some  recognition.  The  humus 
of  the  soil  was  held  to  be  the  source  of  carbon  and  carbonaceous 
matter  for  the  plant.  Humus  and  water  were  considered  the  only 
sources  of  plant  food,  and  the  productive  power  of  the  soil  was 
believed  to  depend  solely  upon  its  humus  content. 

In  the  "Georgical1  Essays"  (Edition  of  1777)  by  Doctor  A. 
Hunter,  which  also  includes  many  essays  or  reports  by  other 
"  philosophical  farmers,"  we  find  the  following  interesting  state- 
ments : 

"The  ancient  writers  gave  us  excellent  comments  upon  the  husbandry  of 
their  times.  Hesiod  wrote  very  early  upon  Agriculture.  Mago,  the  Carthagin- 
ian general,  composed  twenty-eight  books  upon  the  same  subject,  which  were 
translated  by  order  of  the  Roman  Senate.  Upon  these  models  Virgil  formed 
his  elegant  precepts  of  husbandry. 

"Cato,  the  Censor,  wrote  a  volume  upon  Agriculture.  Columella  has  left  us 
twelve  books  upon  rural  matters.  Varro's  treatise  will  ever  be  esteemed.  .  .  . 

"The  celebrated  Sully  calls  Agriculture  one  of  the  breasts  from  which  the 
State  must  draw  its  nourishment.  That  great  man  could  not  possibly  have 
given  us  a  more  happy  simile.  .  .  ." 

"Colbert  entertained  a  different  notion  of  policy.  Esteeming  manufacturers 
and  commerce  as  the  sinews  of  the  State,  he  gave  all  possible  encouragement  to 
the  Artisan  and  the  Merchant,  but  forgot  that  the  manufacturer  must  eat  his 
bread  at  a  moderate  price.  The  farmer  being  discouraged,  the  necessaries  of 

1  Georgical,  like  the  proper  name  George  (Latin  Gear  gins'),  meaning  husband- 
man or  farmer,  is  derived  from  the  Greek  yij  (ge-,  as  in  geology),  the  earth,  and 
tpytiv  (ergein,  as  in  energy),  to  work.  The  Georgics  of  Virgil  are  poems  on  agri- 
cultural affairs. 


THEORIES   CONCERNING   SOIL   FERTILITY       303 

life  became  dear;  the  public  granaries  became  ill  stored;  manufactures  lan- 
guished; commerce  drooped;  a  numerous  army  soon  consumed  the  scanty 
harvest;  and,  in  a  short  time,  Industry  fell  a  sacrifice  to  the  ill-judged  policy  of 
the  minister. 

"From  that  period  to  the  present,  the  French  nation  have  constantly  been 
availing  themselves  of  their  mistake.  Under  the  genial  influence  of  the  King, 
Societies  are  erected  in  every  province.  Men  of  the  first  distinction  do  not  dis- 
dain the  cultivation  of  their  own  lands.  M.  de  Chateauvieux  and  Duhamel  are 
the  greatest  ornaments  of  their  country.  —  Let  us  imitate  the  virtues  of  that  fash- 
ionable nation.  .  .  ." 

f  "The  art  of  husbandry  boasts  an  origin  coeval  with  the  human  race.  Its 
age,  however,  seems  to  have  contributed  but  little  towards  its  advancement, 
being  at  present  extended  but  a  few  degrees  beyond  its  primitive  institution. 
Until  the  philosopher  condescends  to  direct  the  plow,  Husbandry  must  remain 
in  a  torpid  state.  .  .  . 

"  I  take  it  upon  me  to  say,  that,  to  be  a  good  husbandman,  it  is  necessary  to 
be  a  good  chymist.  Chymistry  will  teach  him  the  best  way  to  prepare  nourish- 
ment for  his  respective  crops,  and,  in  the  most  wonderful  manner  will  expose 
the  hidden  things  of  nature  to  his  view.  The  principles  of  Agriculture  depend 
greatly  upon  chymistry;  and  without  principles,  what  is  art,  and  what  is 
science  ?  , 

"Directed  by  instinct,  the  animal  seeks  its  own  proper  food ;  but  the  vegetable, 
not  being  possessed  of  the  power  of  motion,  must  be  satisfied  with  the  nourish- 
ment we  give  it.  To  direct  this  upon  rational  principles,  is  the  business  of  the 
philosopher.  The  practical  farmer  will  suffer  himself  to  be  instructed  as  soon 
as  he  perceives  the  practice  correspond  with  the  theory  laid  down  to  him.  Let 
us  expect  no  more  of  him.  Men  of  limited  education  commit  great  errors  when 
they  attempt  to  reason  upon  science.  In  husbandry,  effects  are  constantly 
applied  to  improper  causes.  Hence  proceed  the  errors  of  our  common  farmers. 
To  overcome  these  is  the  peculiar  province  of  the  philosopher;  who,  in  his  turn, 
must  support  his  reasoning  by  facts  and  experiments. 

"I  lay  it  down  as  a  fundamental  maxim,  that  all  plants  receive  their  principal 
nourishment  from  oily  particles  incorporated  with  water,  by  means  of  an  alka- 
line salt  or  absorbent  earth.  ...  It  may  be  asked,  whence  do  natural  soils 
receive  their  oily  particles?  I  answer,  the  air  supplies  them.  During  the 
summer  months,  the  atmosphere  is  full  of  putrid  exhalations  arising  from  the 
steam  of  dunghills,  the  perspiration  of  animals  and  smoke.  Every  shower 
brings  down  these  oleaginous  particles  for  the  nourishment  of  plants." 

"  The  ingenious  Mr.  Tull,  and  others,  have  contended  for  earth's  being  the 
food  of  plants.  If  so,  all  soils  equally  tilled  would  prove  equally  prolific. 
Water  is  thought,  by  some,  to  be  the  food  of  vegetables,  when  in  reality  it  is  only 
the  vehicle  of  nourishment." 

After  pointing  out  the  great  value  of  oil  meals,  rape  cake,  etc. 
(and  later  of  fish  scrap),  for  soil  improvement,  and  after  noting 


c 


SYSTEMS   OF   PERMANENT   AGRICULTURE 

that  all  seeds  contain  oil,  and  that  hemp,  rape,  and  flax  (rich  in  oil) 
are  very  exhaustive  crops,  Doctor  Hunter  adds,  much  to  his 
credit  as  a  scientist: 

"As  I  have  not  the  vanity  to  think  my  experiments  sufficiently  conclusive, 
I  embrace  this  opportunity  to  request  assistance  of  the  practical  farmer,  in  order 
that  the  merits  of  the  invention  may  be  fully  determined.  Should  my  theory 
concerning  the  food  of  plants  be  thought  erroneous,  the  compost  (made  in  part 
of  crude  whale  oil,  'train  oil')  will  of  course  be  disregarded.  But,  on  the  con- 
trary, should  it  be  agreed  to  that  oil,  made  miscible  with  water,  constitutes  the 
chief  nourishment  of  vegetables,  then  the  invention  will  probably  become  the 
subject  of  future  experiment. 

"Though  theory  may  direct  our  inquiries,  yet  experience  must  at  last  deter- 
mine our  opinions,  for  which  reason  I  propose  to  enlarge  my  experiments;  and 
as  I  have  no  other  view  but  the  investigation  of  the  truth,  I  shall  lay  them  faith- 
fully before  the  public,  whether  they  prove  successful  or  not." 

Among  the  "  Georgical  Essays,"  the  two  reports  which  follow 
are  of  special  interest.  The  first  bears  upon  the  oil  theory,  and  both 
show  evidence  of  the  search  for  truth,  and  indicate  the  approach- 
ing dawn  of  chemical  science.  The  editor  says  that  the  1777  edi- 
tion is  a  reprint,  and  that  "  this  volume  contains  several  additional 
papers";  so  it  is  not  clear  that  Doctor  Hunter  knew  of  these 
experiments. 

"A  COMPARATIVE  VIEW  OF  MANURES 
"  BY  A.  YOUNG,  ESQ. 

"In  the  year  1771, 1  marked  out  a  rood  of  land  into  divisions,  and  sowed  them 
with  oats.  The  variety  of  manures  made  use  of  in  this  experiment  are  marked 
as  follows: 

PRODUCE  PER  ACRE 
No.  B.  P. 

1.  40  cubical  yards  of  farmyard  compost,  and  dung       ...     40  2\ 

2.  20  ditto  .          51  i 

3.  10  ditto 45  o 

4.  10  ditto 46  i 

5.  10  loads  of  bones,  each  40  bushels 63  i 

6.  20  ditto 57  o 

7.  200  bushels  of  lime 38  if 

8.  40  yards  of  chalk 31  r 

9.  No  manure 30  z\ 

10.   80  yards  of  chalk 25  2\ 

n.   120  ditto 27  a 


THEORIES   CONCERNING   SOIL   FERTILITY 


305 


PRODUCE  PER  ACRE 

No.  B.  P. 

12.  40  yards  of  chalk,  earth  mixed  with  train  oil,  six  months  ago, 

and  often  turned 33  o£ 

13.  40  ditto,  earth  mixed  with  urine,  four  months  ago,  and 

often  turned 37  2 

14.  40  ditto,  earth  alone      .     .     ? 33  oj 

15.  40  ditto,  earth  from  the  farmyard 37  2 

16.  1 20  ditto,  red  gravelly  loam 29  T£ 

17.  160  ditto 31  i 

"  N.B.     The  season  was  remarkably  dry,  which  circumstance  certainly  had  a      j 
considerable  effect  upon  the  different  crops."  .  J 

"ON  BONES  USED  AS  A  MANURE 
"By  ANTHONY  ST.  LEGER,  ESQ. 

F" During  a  long  course  of  speculative  and  practical  Agriculture,  in  which, 
with  critical  exactness,  I  employed  myself  in  making  experiments  upon  almost 
every  kind  of  manure,  I  was  fortunate  enough  to  discover  that  bones  are  su- 
perior to  all  the  manures  made  use  of  by  the  farmer. 

"Eight  years  ago  I  laid  down  to  grass  a  large  piece  of  very  indifferent  lime- 
stone land  with  a  crop  of  corn  (Wheat,  presumably) ;  and,  in  order  that  the 
grass  seeds  might  have  a  strong  vegetation,  I  took  care  to  see  it  well  dressed. 
From  this  piece  I  selected  three  roods  of  equal  quality  with  the  rest,  and 
dressed  them  with  bones  broken  very  small,  at  the  rate  of  sixty  bushels  per  acre. 
Upon  lands  thus  managed,  the  crop  of  corn  was  infinitely  superior  to  the  rest. 
The  next  year  the  grass  was  also  superior,  and  has  continued  to  preserve  the 
same  superiority  ever  since,  insomuch  that  in  spring  it  is  green  three  weeks 
before  the  rest  of  the  field.  J 

"This  year  I  propose  toplow  up  the  field  as  the  Festuca  sylvatica  (prye 
grass)  has  overpowered  the  grass  seed  originally  sown.  And  here  it  will  be 
proper  to  remark  that,  notwithstanding  the  species  of  grass  is  the  natural  prod- 
uce of  the  soil,  the  three  roods  on  which  the  bones  were  laid  have  hardly  any 
of  it,  but,  on  the  contrary,  have  all  along  produced  the  finest  grasses. 

Last  year  I  dressed  two  acres  with  bones,  in  two  different  fields  prepared 
'or  turnips,  sixty  bushels  to  the  acre,  and  had  the  pleasure  to  find  the  turnrps 
greatly  superior  to  the  others  managed  in  the  common  way.  I  have  no  doubt 
but  these  two  acres  will  preserve  their  superiority  for  many  years  to  come,  if  I 
may  be  allowed  to  prognosticate  from  former  experiments  most  carefully  con- 
ducted. 

"I  also  dressed  an  acre  of  grass  ground  with  bones  last  October  (1774)  and 
rolled  them  in.  The  succeeding  crop  of  hay  was  an  exceeding  good  one. 
However,  I  found  from  repeated  experience  that,  upon  grass  ground,  this 
kind  of  manure  exerts  itself  more  powerfully  the  second  year  than  the  first. 

"It  must  be  obvious  to  every  person,  that  the  bones  should  be  well  broken 


Ul 

L 


306        SYSTEMS    OF   PERMANENT   AGRICULTURE 

before  they  can  be  equally  spread  upon  the  land.  No  pieces  should  exceed 
the  size  of  marbles^  To  perform  this  necessary  operation,  I  would  recommend 
the  bones  to  be  sufficiently  bruised  by  putting  them  under  a  circular  stone,  which, 

^  being  moved  round  upon  its  edge  by  means  of  a  horse,  in  the  manner  that  tan- 
ners grind  their  bark,  will  very  expeditiously  effect  the  purpose.  At  Sheffield 
it  is  now  become  a  trade  to  grind  bones  for  the  use  of  the  farmer.  Some  people 
break  them  small  with  hammers  upon  a  piece  of  iron,  but  that  method  is  in- 
ferior to  grinding.  (-To  ascertain  the  comparative  merit  of  ground  and  unground 
bones,  I  last  year  dressed  two  acres  of  turnips  with  large  bones,  in  the  same 
field  where  the  ground  ones  were  used ;  the  result  of  this  experiment  was,  that 
the  unground  material  did  not  perform  the  least  service;  while  those  parts  of 
the  field  on  which  the  ground  bones  were  laid  were  greatly  benefited. 

"I  find  that  bones  of  all  kinds  will  answer  the  purpose  of  a  rich  dressing,  but 
those  of  fat  cattle  I  apprehend  are  the  best.  The  London  bones,  as  I  am  in- 
formed, undergo  the  action  of  boiling  water,  for  which  reason  they  must  be 
much  inferior  to  such  as  retain  their  oily  parts;  and  this  is  another  of  the  many 
proofs  given  in  these  essays  that  oil  is  the  food  of  plants.  The  farmers  in  this 
neighborhood  are  become  so  fond  of  this  kind  of  manure,  that  the  price  is  now 
advanced  to  one  shilling  and  fourpence  per  bushel,  and  even  at  that  price  they 
send  sixteen  miles  for  it. 

"I  have  found  it  a  judicious  practice  to  mix  ashes'  with  the  bones;  and  this 
winter  I  have  six  acres  of  meadow  land  dressed  with  that  compost.  A  cart 
load  of  ashes  may  be  put  to  thirty  or  forty  bushels  of  bones,  and  when  they  have 
heated  for  twenty-four  hours  (which  may  be  known  by  the  smoking  of  the  heap) 
let  the  whole  be  turned.  After  laying  ten  days  longer,  this  most  excellent  dress- 
ing will  be  fit  for  use."  Jj 

In  1822,  William  Corbett,  in  his  compilation  of  the  writings  of 
JethroTull,  made  the  following  statements: 

"Mr.  Tull's  main  principle  is  this,  that  tillage  will  supply  the  place  of 
manure;  and  his  own  experience  shows  that  a  good  crop  of  wheat,  for  any 
number  of  years,  may  be  grown  every  year  upon  the  same  land  without  any 
manure  from  first  to  last." 

"  Mr.  Tull  continued  his  wheat  crops  to  the  harvesting  of  the  twelfth  upon  the 
same  land  without  manure;  and  when  he  concluded  his  work,  he  had,  as  he  in- 
forms us  in  a  memorandum,  the  thirteenth  crop  coming  on,  likely  to  be  very 
good." 

It  may  be  stated,  however,  that,  after  the  time  of  Jethro  Tull 
and  before  Corbett's  republication  of  the  Tullian  methods  and 
theories,  some  truly  scientific  facts  had  been  discovered.  In  fact, 
chemistry  had  begun  to  assume  the  character  of  an  exact  science. 
Priestly  had  discovered  oxygen  and  also  identified  as  oxygen  the 
gas  which  others  had  previously  observed  is  given  off  from  the 


THEORIES   CONCERNING   SOIL   FERTILITY        307 

leaves  of  plants  under  the  influence  of  sunlight;1  Senebier  had 
shown  that  the  carbon  of  the  plant  is  derived  from  the  carbon  dioxid 
of  the  air;  and  De  Saussure  had  analyzed  the  ash  of  many  plants, 
had  shown  that  these  ash  constituents  were  derived  from  the  soil, 
and  that,  though  small  in  quantity  as  compared  with  the  amount 
of  material  furnished  to  the  plant  by  the  air  and  water,  the  ash 
constituents  were  also  essential  to  plant  growth. 

De  Saussure's  publication  in  1804  of  his  "  Reserches  Chimique 
sur  la  Vegetation"  gave  to  the  world  the  first  definite  and  approxi- 
mately correct  statement  concerning  the  requirements  and  sources 
of  plant  food.  While  Davy's  lectures  on  Agricultural  Chemistry 
(first  published  in  1813)  did  much  to  extend  the  existing  knowledge, 
and  the  investigations  of  Bousingault  and  Lawes  began  to  develop 
(about  1835),  it  remained  for  Liebig  to  bring  together  the  work  of 
all  and  present  it  in  a  more  comprehensive  form  in  his  "  Organic 
Chemistry  in  its  Application  to  Agriculture  and  Physiology," 
published  in  1840. 

Thus,  while  Liebig  is  popularly  known  as  the  "Father  of  Agri- 
cultural Chemistry,"  the  more  fundamental  contributions  to  knowl- 
edge concerning  soil  fertility  and  plant  growth  have  been  made  by 
Senebier  (of  Switzerland),  De  Saussure  (of  France),  Lawes  and 
Gilbert  (of  England) ,  and  Hellriegel  (of  Germany) ,  the  last  being 
the  discovery  (in  1886)  of  nitrogen  fixation  by  the  root-tubercle 
bacteria  of  legumes. 

Liebig  devoted  much  effort  toward  the  proof  of  his  theory  that 
the  ammonia  of  the  air  is  the  source  of  nitrogen  for  plants;  but 
in  this  he  failed,  and  Lawes  and  Gilbert's  laboratory  and  field 
investigations  at  Rothamsted,  which  were  in  part  planned  for  the 
purpose  of  disproving  Liebig's  nitrogen  theory,  clearly  established 
the  fact  that  in  the  main  the  soil  must  furnish  nitrogen  as  well  as 
the  mineral  elements  of  plant  food. 

The  following  quotations  from  Liebig's  writings  are  interesting; 
and  they  are  also  instructive,  in  that  they  well  illustrate  the  weak- 
ness of  drawing  quantitative  deductions  and  specific  conclusions 
from  qualitative  data  and  general  observations.  Thus  wrote 
Liebig: 

1  Any  one  may  observe  the  bubbles  of  oxygen  formed  upon  fresh  leaves  placed 
under  water  in  the  sunlight. 


3o8       SYSTEMS    OF   PERMANENT   AGRICULTURE 

(  "Let  us  picture  to  ourselves  the  condition  of  a  well-cultured  farm,  so  large 
as  to  be  independent  of  assistance  from  other  quarters.  On  this  extent  of  land 
there  is  a  certain  quantity  of  nitrogen  contained  both  in  the  corn  and  fruit  which 
it  produces,  and  in  the  mefi  and  animals  which  feed  upon  them,  and  also  in  their 
excrements.  We  shall  suppose  this  quantity  to  be  known.  The  land  is  culti- 
vated without  the  importation  of  any  foreign  substance  containing  nitrogen. 
Now,  the  products  of  this  farm  must  be  exchanged  every  year  for  money,  and 
other  necessaries  of  life,  for  bodies,  therefore,  which  contain  no  nitrogen.  A 
certain  proportion  of  nitrogen  is  exported  with  corn  and  cattle;  and  this  ex- 
portation takes  place  every  year,  without  the  smallest  compensation ;  yet  after 
a  number  of  years,  the  quantity  of  nitrogen  will  be  found  to  have  increased. 
Whence,  we  may  ask,  comes  this  increase  of  nitrogen  ?  The  nitrogen  in  the  ex- 
crements cannot  reproduce  itself,  and  the  earth  cannot  yield  it.  Plants,  and  con- 
sequently animals,  must,  therefore,  derive  their  nitrogen  from  the  atmosphere. 

"The  last  products  of  the  decay  and  putrefaction  of  animal  bodies  present 
themselves  in  two  different  forms.  They  are  in  the  form  of  a  combination  of 
hydrogen  and  nitrogen,  —  ammonia,  in  the  temperate  and  cold  climates,  and 
in  that  of  a  compound,  containing  oxygen,  nitric  acid,  in  the  tropics  and  hot 
climates.  The  formation  of  the  latter  is  preceded  by  the  production  of  the 
first.  Ammonia  is  the  last  product  of  the  putrefaction  of  animal  bodies;  nitric 
acid  is  the  product  of  the  transformation  of  ammonia.  A  generation  of  a 
thousand  million  men  is  renewed  every  thirty  years :  thousands  of  millions  of 
animals  cease  to  live  and  are  reproduced  in  a  much  shorter  period.  Where  is 
the  nitrogen  which  they  contained  during  life?  There  is  no  question  which 
can  be  answered  with  more  positive  certainty.  All  animal  bodies,  during  their 
decay,  yield  the  nitrogen,  which  they  contain  to  the  atmosphere,  in  the  form  of 
ammonia.  Even  in  the  bodies  buried  sixty  feet  underground  in  the  church- 
yard of  the  Eglise  des  Innocens,  at  Paris,  all  the  nitrogen  contained  in  the  adi- 
pocere  was  in  the  state  of  ammonia.  Ammonia  is  the  simplest  of  all  the  com- 
pounds of  nitrogen ;  and  hydrogen  is  the  element  for  which  nitrogen  possesses 
the  most  powerful  affinity.) 

"The  nitrogen  of  putrefied  animals  is  contained  in  the  atmosphere  as  ammonia 
in  the  form  of  a  gas  which  is  capable  of  entering  into  combination  with  carbonic 
acid,  and  of  forming  a  volatile  salt.  Ammonia  in  its  gaseous  form  as  well  as  all 
its  volatile  compounds  are  of  extreme  solubility  in  water.  Ammonia,  there- 
fore, cannot  remain  long  in  the  atmosphere,  as  every  shower  of  rain  must  con- 
dense it,  and  convey  it  to  the  surface  of  the  earth.  Hence,  also,  rain  water 
must,  at  all  times,  contain  ammonia,  though  not  always  in  equal  quantity.  It 
must  be  greater  in  summer  than  in  spring  or  in  winter,  because  the  intervals 
of  time  between  the  showers  are  in  summer  greater;  and  when  several  wet  days 
occur,  the  rain  of  the  first  must  contain  more  'of  it  than  that  of  the  second. 
The  rain  of  a  thunderstorm,  after  a  long-protracted  drought,  ought  for  this 
reason  to  contain  the  greatest  quantity,  which  is  conveyed  to  the  earth  at  one 
time.  .  .  ." 

"If  a  pound  of  rain  water  contain  only  one  fourth  of  a  grain  of  ammonia, 


THEORIES    CONCERNING   SOIL   FERTILITY        309 

then  a  field  of  40,000  square  feet  must  receive  annually  upwards  of  80  Ib.  of 
ammonia,  or  65  Ib.  of  nitrogen;  for,  by  the  observations  of  Schubler,  which 
were  formerly  alluded  to,  about  700,000  Ib.  of  rain  fall  over  this  surface  in  four 
months,  and  consequently  the  annual  fall  must  be  2,500,000  Ib.  This  is  much 
more  nitrogen  than  is  contained  in  the  form  of  vegetable  albumen  and  gluten, 
in  2650  Ib.  of  wood,  2800  Ib.  of  hay,  or  200  cwt.  of  beet  root,  which  are  the 
yearly  produce  of  such  a  field,  but  it  is  less  than  the  straw,  roots,  and  grain  of 
corn  which  might  grow  on  the  same  surface,  would  contain. 

"Experiments,  made  in  this  laboratory  (Giessen)  with  the  greatest  care  and 
exactness,  have  placed  the  presence  of  ammonia  in  rain  water  beyond  all 
doubt.  It  has  hitherto  escaped  observation,  because  no  person  thought  of 
searching  for  it.1  All  the  rain  water  employed  in  this  inquiry  was  collected 
600  paces  southwest  of  Giessen,  whilst  the  wind  was  blowing  in  the  direction  of 
the  town.  When  several  hundred  pounds  of  it  were  distilled  in  a  copper  still, 
and  the  first  two  or  three  pounds  evaporated  with  the  addition  of  a  little  muriatic 
acid,  HC1,  a  very  distinct  crystallization  of  sal-ammoniac  (NH4C1)  was,  ob- 
tained :  the  crystals  had  always  a  brown  or  yellow  color. 

"Ammonia  may  likewise  be  always  detected  in  snow  water.  Crystals  of 
sal-ammoniac  were  obtained  by  evaporating  in  a  vessel  with  muriatic  acid 
several  pounds  of  snow,  which  were  gathered  from  the  surface  of  the  ground  in 
March,  when  the  snow  had  a  depth  of  10  inches.  Ammonia  was  set  free  from 
these  crystals  by  the  addition  of  hydrate  of  lime.  The  inferior  layers  of  snow, 
which  rested  upon  the  ground,  contained  a  quantity  decidedly  greater  than 
thftse^vhich  formed  the  surface. 

uf'It  is  worthy  of  observation,  that  the  ammonia  contained  in  rain  and  snow 
water  possesses  an  offensive  smell  of  perspiration  and  animal  excrements,  — 
a  fact  which  leaves  no  doubt  respecting  its  origin.  .  .  ." 

"We  find  this  nitrogen  in  the  atmosphere,  in  rain  water,  and  in  all  kinds  of 
soils,  in  the  form  of  ammonia,  as  a  product  of  the  decay  and  putrefaction  of  pre- 
ceding generations  of  animals  and  vegetables.  We  find,  likewise,  that  the  pro- 
portion of  azotized  matters  in  plants  is  augmented  by  giving  them  a  larger 
supply  of  ammonia  conveyed  in  the  form  of  animal  manure. 

"No  conclusion  can  then  have  a  better  foundation  than  this,  that  it  is  the 
ammonia  of  the  atmosphere  which  furnishes  nitrogen  to  plants."  ) 

As  an  average  of  15  years,  the  total  amount  of  nitrogen  brought 
to  earth  in  rain  and  snow  was  found  to  be  3.97  pounds  per  acre  per 
annum,  at  Rothamsted.  Other  records,  varying  from  3  to  7  years, 
have  shown  3.45  pounds  per  acre  per  annum  on  the  Barbados 
Islands,  3.54  pounds  in  British  Guiana,  3.69  pounds  in  Kansas, 
5.42  pounds  in  Utah,  and  3.64  pounds  in  Mississippi;  while  the 
records  from  Paris  show  8.93  pounds,  and  those  from  Gembloux, 

1  "  It  has  been  discovered  by  Mr.  Hayes  in  the  rain  water  in  Vermont."  — W. 


3io 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


Belgium,  9.20  pounds,  both  of  which  are  doubtless  influenced  by 
the  atmosphere  from  the  cities  with  their  numerous  factories  and 
other  sources  of  pollution. 

Professor  Shutt  reports  4.32  pounds  of  nitrogen  per  acre  in  one 
year's  precipitation  at  Ottawa,  Canada,  in  37.35  inches,  of  which 
3.24  pounds  were  found  in  24.05  inches  of  rain  and  1.08  pounds  in 
13.3  inches  of  snow  water  (corresponding  to  about  133  inches  of 
snow),  the  average  composition  being  based  upon  analyses  of  46 
samples  of  rain  water  and  32  samples  of  snow  water.  Of  the  nitro- 
gen found  in  rain  water,  61  per  cent  existed  in  free  ammonia,  22 
per  cent  in  nitrate  (and  nitrite)  form,  and  17  per  cent  as  organic 
nitrogen,  the  corresponding  percentages  for  snow  water  being  56, 
34,  and  10. 

Liebig  also  discussed  very  interestingly  and,  in  the  main,  very 
erroneously,  the  reasons  for  the  value  of  crop  rotation.  In  1840 
he  wrote  as  follows: 

"Of  all  the  views  which  have  been  adopted  regarding  the  cause  of  the  favor- 
able effects  of  the  alternations  of  crops,  that  proposed  by  M.  Decandolle  alone 
deserves  to  be  mentioned  as  resting  on  a  firm  basis. 

"  Decandolle  supposes  that  the  roots  of  plants  imbibe  soluble  matter  of  every 
kind  from  the  soil,  and  thus  necessarily  absorb  a  number  of  substances  which 
are  not  adapted  to  the  purposes  of  nutrition,  and  must  subsequently  be  expelled 
by  the  roots,  and  returned  to  the  soil  as  excrements.  Now  as  excrements  can- 
not be  assimilated  by  the  plant  which  ejected  them,  the  more  of  these  matters 
which  the  soil  contains,  the  more  unfertile  must  it  be  for  plants  of  the  same 
species.  These  excrementitious  matters  may,  however,  still  be  capable  of  as- 
similation by  another  kind  of  plants,  which  would  thus  remove  from  the  soil, 
and  render  it  again  fertile  for  the  first.  And  if  the  plants  last  grown  also  expel 
substances  from  their  roots,  which  can  be  appropriated  as  food  by  the  former, 
they  will  improve  the  soil  in  two  ways. 

"  Now  a  great  number  of  facts  appear  at  first  sight  to  give  a  high  degree  of 
probability  to  this  view.  Every  gardener  knows  that  a  fruit  tree  cannot  be 
made  to  grow  on  the  same  spot  where  another  of  the  same  species  has  stood ; 
at  least  not  until  after  a  lapse  of  several  years.  Before  new  vine  stocks  are 
planted  in  a  vineyard  from  which  the  old  have  been  rooted  out,  other  plants  are 
cultivated  on  the  soil  for  several  years.  In  connection  with  this  it  has  been  ob- 
served, that  several  plants  thrive  best  when  growing  beside  one  another;  and,  on 
the  contrary,  that  others  mutually  prevent  each  other's  development.  Whence 
it  was  concluded,  that  the  beneficial  influence  in  the  former  case  depended  on  a 
mutual  interchange  of  nutriment  between  the  plants,  and  the  injurious  one  in  the 
latter  on  a  poisonous  action  of  the  excrements  of  each  on  the  other  respectively. 


THEORIES   CONCERNING   SOIL   FERTILITY 

"A  series  of  experiments  by  Macaire-Princep  gave  great  weight  to  this  theory. 
He  proved  beyond  all  doubt  that  many  plants  are  capable  of  emitting  extractive 
matter  from  their  roots.  He  found  that  the  excretions  were  greater  durihg 
the  night  than  by  day,  and  that  the  water  in  which  plants  of  the  family  of  the 
Leguminosce  grew,  acquired  a  brown  color.  Plants  of  the  same  species,  placed 
in  water  impregnated  with  these  excrements,  were  impeded  in  their  growth, 
and  faded  prematurely,  whilst,  on  the  contrary,  corn  plants  grew  vigorously  in 
it,  and  the  color  of  the  water  diminished  sensibly;  so  that  it  appeared,  as  if  a 
certain  quantity  of  ^ie  excrements  of  the  Leguminosce  had  really  been  absorbed 
by  the  corn  plants.jThese  experiments  afforded  as  their  main  result,  that  the 
characters  and  p*j^>erties  of  the  excrements  of  different  species  of  plants  are 
different  from  one  another,  and  that  some  plants  expel  excrementitious  matter 
of  an  acrid  and  resinous  character;  others  mild  (douce)  substances  resembling 
gum.  The  former  of  these,  according  to  Macaire-Princep,  may  be  regarded 
as  poisonous,  the  latter  as  nutritious. 

"The  experiments  of  Macaire-Princep  are  positive  proof  that  the  roots,  prob- 
ably of  all  plants,  expel  matters,  which  cannot  be  converted  in  their  organism 
either  into  woody  fiber,  starch,  vegetable  albumen,  or  gluten,  since  their  ex- 
pulsion indicates  that  they  are  quite  unfitted  for  this  purpose.  But  they  cannot 
be  considered  as  a  confirmation  of  the  theory  of  Decandolle,  for  they  leave  it 
quite  undecided  whether  the  substances  were  extracted  from  the  soil,  or  formed 
by  the  plant  itself  from  food  from  another  source.  It  is  certain  that  the 
gummy  and  resinous  excrements  observed  by  Macaire-Princep  could  not  have 
been  contained  in  the  soil ;  and  as  we  know  that  the  carbon  of  a  soil  is  not 
diminished  by  culture,  but,  on  the  contrary,  increased,  we  must  conclude 
that  all  excrements  which  contain  carbon  must  be  formed  from  the  food  ob- 
tained by  plants  from  the  atmosphere.  Now,  these  excrements  are  compounds, 
produced  in  consequence  of  the  transformations  of  the  food,  and  of  the 
new  forms  which  it  assumes  by  entering  into  the  composition  of  the  various 
;ans. 

"M.  Decandolle's  theory  is  properly  a  modification  of  an  earlier  hypothesis, 

hich  supposed  that  the  roots  of  different  plants  extracted  different  nutritive 
substances  from  the  soil,  each  plant  selecting  that  which  was  exactly  suited  for 
its  assimilation.  According  to  this  hypothesis,  the  matters  incapable  of  as- 
similation are  not  extracted  from  the  soil,  whilst  M .  Decandolle  considers  that 
they  are  returned  to  it  in  the  form  of  excrements.  Both  views  explain  how  it 
happens  that  after  corn,  corn  cannot  be  raised  with  advantage,  nor  after  peas, 
peas ;  but  they  do  not  explain  how  a  field  is  improved  by  lying  fallow,  and  this 
in  proportion  to  the  care  with  which  it  is  tilled  and  kept  free  from  weeds;  nor 
do  they  show  how  a  soil  gains  carbona<j£pus  matter  by  the  cultivation  of  certain 
plants,  such  as  lucern  and  esparsette.  j 

"Theoretical  considerations  on  the  process  of  nutrition,  as  well  as  the  ex- 
perience of  all  agriculturists,  so  beautifully  illustrated  by  the  experiments  of 
Macaire-Princep,  leave  no  doubt  that  substances  are  excreted  from  the  roots  of 
plants.  .  .  ." 


312       SYSTEMS   OF   PERMANENT   AGRICULTURE 

"It  is  scarcely  necessary  to  remark  that  this  excrementitious  matter  must 
undergo  a  change  before  another  season.  During  autumn  and  winter  it  begins 
to  suffer  a  change  from  the  influence  of  air  and  water ;  its  putrefaction,  and,  at 
length,  by  continued  contact  with  the  air,  which  tillage  is  the  means  of  procur- 
ing, its  decay  are  effected ;  and  at  the  commencement  of  spring  it  has  become 
converted,  either  in  whole  or  in  part,  into  a  substance  which  supplies  the  place 
of  humus,  by  being  a  constant  source  of  carbonic  acid. 

"  The  quickness  with  which  this  decay  of  the  excrements  of  plants  proceeds, 
depends  on  the  composition  of  the  soil,  and  on  its  greater  or  less  porosity.  It 
will  take  place  very  quickly  in  a  calcareous  soil ;  for  the  power  of  organic  ex- 
crements to  attract  oxygen  and  to  putrefy  is  increased  by  contact  with  the  al- 
kaline constituents,  and  by  the  general  porous  nature  of  such  kinds  of  soil, 
which  freely  permit  the  access  of  air.  But  it  requires  a  longer  time  in  heavy 
soils  consisting  of  loam  or  clay. 

"The  same  plants  can  be  cultivated  with  advantage  on  one  soil  after  the 
second  year,  but  in  others  not  until  the  fifth  or  ninth,  merely  on  account  of  the 
change  and  destruction  of  the  excrements  which  have  an  injurious  influence  on 
the  plants  being  completed  in  the  one,  in  the  second  year;  in  the  others,  not 
until  the  ninth. 

"In  some  neighborhoods,  clover  will  not  thrive  until  the  sixth  year;  in  others 
not  till  the  twelfth ;  flax  in  the  second  or  third  year.  All  this  depends  on  the 
chemical  nature  of  the  soil ;  for  it  has  been  found  by  experience  that  in  those 
districts  where  the  intervals  at  which  the  same  plants  can  be  cultivated  with 
advantage,  are  very  long,  the  time  cannot  be  shortened  even  by  the  use  of  the 
most  powerful  manures.  The  destruction  of  the  peculiar  excrements  of  one 
crop  must  have  taken  place  before  a  new  crop  can  be  produced. 

"Flax,  peas,  clover,  and  even  potatoes,  are  plants  the  excrements  of  which, 
in  argillaceous  soils,  require  the  longest  time  for  their  conversion  into  humus; 
but  it  is  evident,  that  the  use  of  alkalies  and  burnt  lime,  or  even  small  quantities 
of  ashes  which  have  been  lixiviated,  must  enable  a  soil  to  permit  the  cultivation 
of  the  same  plants  in  a  much  shorter  time. 

"A  soil  lying  fallow  owes  its  early  fertility,  in  part,  to  the  destruction  or  con- 
version into  humus  of  the  excrements  contained  in  it,  which  is  effected  during 
the  fallow  season,  at  the  same  time  that  the  land  is  exposed  to  a  further  disinte- 
gration." 

In  the  first  American  edition  of  Liebig's  book,  published  in  1841, 
Doctor  John  W.  Webster,  then  Professor  of  Chemistry  in  Harvard 
University,  inserted  an  appendix,  in  which  he  wrote  as  follows: 

"It  should  be  stated  that  the  accuracy  of  the  experiments  of  Macaire:Princep 
adduced  by  the  author  (Liebig)  is  not  generally  admitted.  Other  chemists 
have  been  unable  to  obtain  similar  results,  or,  if  they  do,  are  inclined  to  ascribe 
them  to  injury  of  the  roots  of  the  plants  examined.  Professor  Lindley  has  in 
his  notice  of  Liebig's  work  remarked  that  he  has  no  fixed  opinion  on  the  sub- 
ject, it  being  a  question  of  facts  and  not  of  induction." 


u 

f. 


THEORIES    CONCERNING   SOIL   FERTILITY       313 

Liebig  so  emphasized  the  importance  of  the  mineral  plant  food, 
as  established  by  De  Saussure's  careful  work,  that  it  has  ever  since 
been  referred  to  as  "  Liebig's  mineral  theory  of  plant  nutrition." 

In  recent  years,  Whitney  and  Cameron  have  revived  Decandolle's 
theory  of  toxic  excreta  from  plant  roots,  in  support  of  another  more 
radical  theory  announced  by  them,  to  the  effect  that  soils  do  not 
wear  out  or  become  depleted  by  cultivation  and  cropping.  While 
this  theory  is  advanced  with  no  adequate  foundation  and  in  direct 
opposition  to  practical  experience  and  to  so  many  known  facts  of 
mathematics,  chemistry,  and  geology,  that  it  is  in  itself  quite 
unworthy  of  further  consideration,  the  fact  is  that  it  has  been  pro- 
mulgated by  Professor  Whitney  as  Chief  of  the  United  States 
Bureau  of  Soils,  and  by  Doctor  Cameron,  as  the  chief  chemist  of  the 
same  Bureau;  and,  consequently,  it  cannot  be  ignored. 

The  author  finds  practically  no  support  for  these  radical  theories, 
either  in  the  American  Experiment  Station  bulletins  or  in  the 
publications  from  the  older  scientific  bureaus  at  Washington, 
such  as  the  United  States  Geological  Survey,  the  Bureau  of  Chem- 
istry, and  the  Bureau  of  Plant  Industry;  while  they  are  directly 
contrary  to  the  teachings  of  all  recognized  European  authorities. 
But  even  above  any  so-called  authorities,  we  must  recognize  facts, 
if  there  are  any,  for  an  opinion  contrary  to  the  facts  is  of  no  per- 
manent value  by  whomsoever  it  may  be  held. 

The  following  statements  from  Whitney  and  Cameron  will  give 
a  clear  idea  of  the  plain  teachings  of  the  Bureau  of  Soils,  so  far  as 
represented  by  its  leaders. 

Thus,  on  page  64  of  Bulletin  22  of  the  Bureau  of  Soils,  published 
by  Whitney  and  Cameron  in  1903,  we  read: 

"  That  practically  all  soils  contain  sufficient  plant  food  for  good  crop  yields, 
that  this  supply  will  be  indefinitely  maintained,"  jetc.  d 

Again,  on  pages  21  and  22,  Farmers'  Bulletin  257,  published  in 
1906,  we  have  the  following  definite  statements  from  Professor 
Whjtney: 

a' There  is  another  way  in  which  the  fertility  of  the  soil  can  be  maintained, 
viz.,  by  arranging  a  system  of  rotation  and  growing  each  year  a  crop  that  is  not 
injured  by  the  excreta  of  the  preceding  crop;  then  when  the  time  comes  round 
for  the  first  crop  to  be  planted  again,  the  soil  has  had  ample  time  to  dispose  of  the 
sewage  resulting  from  the  growth  of  the  plant  two  or  three  years  before.  This,  I 


3H       SYSTEMS    OF   PERMANENT   AGRICULTURE 

think,  is  the  basis  or  reason  in  many  cases  for  our  crop  rotation,  viz.,  that  these 
excreted  substances  are  not  toxic  alike  for  all  plants,  and  the  soil  has  time  to 
recover  its  tone  and  cleanse  itself.  I  have  told  you  that  barley  will  follow  po- 
tatoes in  the  Rothamsted  experiments  after  the  potatoes  have  grown  so  long  that 
the  soil  will  not  produce  potatoes.  The  barley  grows  unaffected  by  the  excreta 
of  the  potatoes,  another  crop  follows  the  barley,  and  the  soil  is  then  in  condition 
to  grow  potatoes  again."  \ 

Again  in  the  report  of  the  Hearings  before  the  Committee  on 
Agriculture  of  the  United  States  House  of  Representatives, 
under  date  of  January  28,  1908,  page  428,  we  find  the  following 
statements  by  Professor  Whitney: 

"The  investigations  of  the  Bureau  of  Soils,  as  to  the  cause  of  the  deterioration 
of  soils,  and  the  causes  that  limit  crop  production,  have  changed  the  viewpoint 
of  the  entire  world." 

On  pages  445-449  of  the  same  publication,  Doctor  Cameron 
kes  the  following  statements: 

"All  soils  contain  practically  all  the  common  rock-forming  minerals.  Now, 
it  is  a  principle  of  chemistry  that  when  a  solvent  is  brought  in  contact  with  a 
substance,  that  substance  will  go  into  solution  until  there  is  a  state  of  equilib- 
rium between  the  quantity  of  the  substance  outside  and  inside;  in  other  words, 
we  get  a  saturated  solution.  If  these  rock-forming  minerals  were  in  all  soils,  we 
should  have  the  same  solution  in  every  soil,  and  that  has  been  shown  to  be  the 
case.  There  are  various  variations,  due  to  absorption,  perhaps,  of  the  soil. 
In  the  first  place,  I  must  ask  you  gentlemen  to  remember  that  the  soil  and  the 
plant  and  the  water  in  the  soil  is  moving.  The  soil  grains  are  constantly 
moving,  and  the  solution  in  the  soil  is  constantly  moving,  and  the  growing 
plant  is  constantly  moving.  If  a  plant  stops  for  a  moment,  it  dies.  The  soil 
solution  cannot  stop  for  a  moment,  because  it  has  to  be  moving  all  the  time. 
When  water  falls  on  the  soil,  part  of  it  runs  off  the  surface,  and  part  of  it  runs 
through  the  surface  by  gravitation  and  comes  out  in  the  subsoil,  and  part  of 
it  starts  and  rises  as  soon  as  we  get  sunlight  on  the  surface,  and  this  part  comes 
up  in  films  over  and  through  the  finer  spaces,  and  is  bringing  with  it  dissolved 
material  from  below. 

"The  water  that  falls  and  goes  through  down  and  out  goes  rapidly  through 
larger  openings,  and  gets  very  little  of  the  soluble  material,  because  it  is  not  long 
in  contact  with  the  soil  grains.  It  gets  some  by  reason  of  the  fact  that,  as  we 
know,  our  springs  and  rivers  and  wells  are  all  soil  solutions,  and  carry  mineral 
matter.  Now,  water  rising  by  capillarity  cannot  get  very  concentrated  be- 
cause it  gets  saturated  with  the  minerals,  and  any  excess  that  is  contained  in  it 
is  thrown  out,  except  in  extreme  conditions,  as  in  the  West,  and  then  we  get 
alkali  conditions;  but  under  ordinary  humid  conditions  we  cannot  have  an 
excess  of  it,  and  the  soil  solution  is  bringing  materials  from  below  which  the 


THEORIES    CONCERNING   SOIL   FERTILITY       315 

plant  gets,  and,  as  a  matter  of  fact,  the  most  important  discovery  of  the  Bureau 
of  Soils  in  recent  years  is  that  plants  are  feeding  on  material  from  the  subsoils, 
far  below  where  the  roots  go."  "\ 

Subsequent  to  this  statement,  the  following  dialogue  is  recorded : 

The  Chairman.  "When  you  say  that  all  soils  contain  all  the  elements  of 
plant  food,  and  there  is  in  those  soils  at  all  times  a  saturated  solution  of  which 
all  these  elements  of  plant  food  make  a  part,  do  you  not  practically  say  that  all 
soils  have  all  the  plant  food  they  need,  and  that  it  is  at  all  times  available  for  the 
plant ;  or  is  it  not  available  for  the  plant  if  it  is  in  a  saturated  solution  ?  " 

Mr.  Cameron.  "Certainly,  if  there  is  water   enough;  if  the  soil  is  moist." 

The  Chairman.  "Is  it  not  therefore  a  justifiable  inference  from  what  you 
have  said,  that  there  is  all  the  time  in  all  soils  enough  plant  food  available  for 
plant  life?" 

Mr.  Cameron.  "True;  perfectly  true  as  regards  mineral  nutrients." 

The  Chairman.  "Then  I  come  back  again  to  the  question,  why  is  it  neces- 
sary, or  is  it  in  your  judgment  necessary,  ever  at  any  time  to  introduce  fertiliz- 
ing material  into  any  soil  for  the  purpose  of  increasing  the  amount  of  plant  food 
in  that  soil." 

Mr.  Cameron.  "Not  in  my  judgment." 

The  Chairman.  "Then  in  your  judgment  the  only  reason  for  the  introduc- 
tion of  fertilizers  is  for  the  antitoxic  effect  or  the  mechanical  effect  they  may  have 
on  the  soil." 

Mr.  Cameron.  "Mainly  that,  but  there  are  other  functions  of  fertilizers  that 
we  know  comparatively  little  about.  We  know  that  certain  kinds  of  life, 
bacteria,  molds,  can  grow  in  certain  solutions  of  salts,  and  cannot  in  others. 
It  may  be  that  fertilizers  affect  them.  But  all  that  is  an  unexplored  field,  and 
little  is  known  about  it.  ...  If  you  will  allow  me  to  say  one  more  word  about 
fertilizers:  What  are  fertilizers?  What  are  the  characteristics  that  a  substance 
must  have  in  order  to  be  a  fertilizer?  It  must  be  obtained  in  large  quantities. 
It  must  also  be  cheap.  Now,  the  substances  which  are  used  as  fertilizing  mate- 
rial are  substances  which  can  be  obtained  in  large  quantities.  They  are  sub- 
stances, and  are»the  only  substances,  which  we  can  get  hold  of  that  we  can 
get  in  large  quantities,  that  we  can  get  cheap,  and  with  one  exception  —  that  is, 
sodium  chlorid  —  common  salt.  It  has  not  been  much  used  as  a  fertilizer, 
because  it  has  not  any  so-called  plant  food  in  it ;  and  yet  it  has  been  used  in  quite 
a  large  number  of  experiments  on  quite  a  large  scale,  and  wherever  it  has  been 
used,  it  has  generally  been  found  to  be  quite  a  good  fertilizer.  In  the  investiga- 
tions of  the  Bureau  we  have  used  pyrogallol.  It  contains  no  plant  food,  but 
carbon,  hydrogen,  and  oxygen,  yet,  nevertheless,  it  is  a  powerful  fertilizer; l  but 

1  Director  Wheeler  of  the  Rhode  Island  Agricultural  Experiment  Station  reported 
to  the  Graduate  School  of  Agriculture  held  at  Cornell  University,  July,  1908,  that 
a  thorough  investigation  under  field  conditions  at  the  Rhode  Island  Station 
showed  practically  no  benefit  from  the  use  of  pyrogallol  as  a  fertilizer;  whereas, 
very  marked  effects  were  produced  by  manures  and  commerical  fertilizers.  —  C.G.H. 


316 

cannot  be  obtained  cheaply.    It  is  worth  over  $2  a  pound,  and  nobody  would 
think  of  recommending  it  as  a  fertilizer.  .  .  ." 

"There  has  not  been  a  publication  on  the  subject  of  soil  fertility  going  out 
from  the  Bureau  of  Soils  —  and  I  think  I  can  speak  advisedly,  for  every  one 
has  gone  through  my  hands  —  in  which  we  did  not  have  the  experimental  proof 
long  before  the  publication  went  out,  and  that  this  is  being  recognized  I  think 
I  can  claim  by  the  fact  that  a  number  of  agricultural  colleges  in  the  country 
are  using  our  bulletins  as  text-books.  I  have  recently  come  from  a  lecture 
trip  extending  from  Louisiana  to  Michigan,  and  I  found  everywhere  that  this 
is  being  taught,  and,  as  I  say,  our  publications  are  being  used  for  text-books." 

On  page  5  of  Farmers'  Bulletin  257,  Professor  Whitney  makes 
the  following  statements: 

"I  shall  be  glad,  however,  to  speak  of  certain  general  features  of  the  essential 
and  broadly  applicable  laws  of  soil  fertility  that  the  Bureau  of  Soils,  with  its 
large  force  of  field  men  and  its  large  force  of  chemists  and  soil  physicists,  has 
investigated  in  the  last  twelve  years.  We  think  that  as  a  result  of  this  work 
we  understand  far  more  of  the  principles  of  soil  fertility  now  than  we  ever  have 
before,  and  I  wish  to  give  the  results  in  words  as  simple  as  possible.  You  need 
not  necessarily  believe  everything  I  say  (because  I  cannot  say  truly  that  I 
believe  everything  myself,  but  only  that  our  opinions  seem  reasonable  deduc- 
tions)." 

In  general,  the  soil  fertility  theories  of  Whitney  and  Cameron 
may  be  briefly  summarized  in  the  following  statements,  all  of 
which  are  direct  quotations: 

1.  "It  appears  further  that  practically  all  soils  contain  sufficient  plant  food 
for  good  crop  yields,  that  this  supply  will  be  indefinitely  maintained,  and  that 
the  actual  yield  of  plants  adapted  to  the  soil  depends  mainly,  under  favorable 
climatic  conditions,  upon  the  cultural  methods  and  suitable  crop  rotation." 

—WHITNEY  and  CAMERON,  in  Bureau  of  Soils  Bulletin  22,  page  .64. 

2.  "In  all  soils  there  are  rock  particles  or  minerals  containing  phosphoric 
acid  and  potash,  and  in  all  the  soil  solutions  that  we  have  ever  examined  — 
and  we  have  examined  hundreds  of  them  from  all  parts  of  the  country  —  you 
will  be  astonished  to  learn  that  the  composition  and  concentration  of  the  soil 
moisture,   which   is   the   nutrient   solution  spread    throughout   the   surface 
soil  of  the  earth  for  plants  to  grow  in  and  to  gather  their  food  from, — 
you  will  be  astonished  to  learn  that  the  concentration  of  this  soil  moisture  is 
sensibly  the  same  whether  we  examine  your  sandy  truck  soils  on  your  river  necks, 
your  sandy  clay  wheat  soils  on  the  uplands,  the  Hagerstown  flay  in  the  valley 
of  the  Shenandoah,  or  the  black  prairie  soils  of  the  West.    These  minerals 
are  contributing  to  the  solution  in  which  the  plant  feeds.    As  I  have  said,  these 
minerals  are  difficultly  soluble,  but  they  are  appreciably  soluble.    They  are 
soluble  enough  to  maintain  a  solution  which  is  amply  sufficient  for  the  plants  to 


THEORIES    CONCERNING   SOIL   FERTILITY       317 

gather  their  food  from.    All  soils  having,  broadly  speaking,  all  of  these  minerals 
in  them,  have  approximately  the  same  composition  in  their  soil  moisture. 

"This  is  a  very  astonishing  fact,  but,  looked  upon  in  the  light  of  our  experi- 
ments, it  is  an  actual  fact  that  all  soils  contain  sufficient  plant  food  for  the  sup- 
port of  plants.  Further,  when  the  plant  takes  into  its  substance  some  of  the 
mineral  matter  from  the  solution,  the  solid  minerals  in  contact  with  the  solution 
immediately  dissolve,  and  the  solution  is  restored  to  its  former  concentration. 
The  exhaustion  of  the  soil,  therefore,  is  merely  a  relative  phrase  and  resolves 
itself  into  the  question  of  the  rate  at  which  the  solution  can  recover  itself. 
I  may  state  to  you  that  the  rate  is  as  fast  on  an  acre  planted  in  our  ordinary  crops 
as  the  demand  made  upon  it  by  the  plant." 

—  WHITNEY,  in  Farmers'  Bulletin  257,  pages  10,  n. 

3.  "It  is  not  to  be  denied  that  plants  will  not  infrequently  do  better  when 
they  are  growing  in  a  soil,  a  nutrient  solution,  or  a  soil  solution  many  times 
stronger  than  they  actually  need.  .  .  . 

"If  we  take  a  plant  and  grow  it  in  a  water  culture,  the  plant  does  better  if  we 
have  a  solution  containing  several  times  more  phosphorus  and  potash  than  it 
actually  needs  to  feed  on.  Why  it  is  we  do  not  know,  but  granting  that  the  plant 
does  better  in  a  solution  stronger  than  it  actually  needs  as  a  food,  we  still  have 
a  solution  in  the  soil  apparently  strong  enough  for  any  need  the  plant  may  have. 

"Now  we  come  to  a  very  interesting  thing  to  the  farmer.  If  soils  have  suffi- 
cient food  for  the  needs  of  plants  and  if  this  supply  is  constantly  maintained,  as 
I  say,  by  the  solution  of  these  minerals  in  the  soil,  then  what  is  the  function  of 
fertilizers,  and  what  do  we  mean  by  worn-out  lands  or  exhausted  lands  ?  .  .  . 
The  chemical  idea  of  the  exhaustion  of  a  soil  is  not  logical  in  the  light  of  the  ex- 
perience which  all  of  us  have  seen,  that  when  fertilizers  are  applied,  the  soils  are 
not  always  made  immediately  productive.  You  can  go  into  many  of  the  regions 
of  the  worn-out  soils  of  our  Eastern  states  and  reclaim  those  soils  or  make 
them  productive,  but  not  with  any  amount  of  fertilizers  you  can  apply." 

"I  should  say  that  the  soil  ought  to  take  care  of  the  excrement  of  plants.  It 
is  its  business  to  do  so.  It  is  its  proper  function.  Whether  it  does  this  through 
the  agency  of  bacteria,  whether  it  is  due  to  the  abnormal  absorptive  power  of 
the  soil  or  to  direct  oxidation,  we  do  hot  know.  It  is  probably  due  in  part  to 
each.  Take  a  natural  soil,  a  prairie  sod;  the  sanitary  conditions  in  that  soil 
are  almost  perfect."  1 

—  WHITNEY,  in  Farmers'  Bulletin  257,  pages  n,  12,  and  15. 

4.  "Apparently  these  small  amounts  of  fertilizers  we  add  to  the  soil  have 
their  effect  upon  these  toxic  substances  and  render  the  soil  sweet  and  more 
healthful  for  growing  plants.    We  believe  that  it  is  through  this  means  that  our 
fertilizers  act  rather  than  through  the  supplying  of  plant  food  to  the  plant." 

—  WHITNEY,  in  Farmers'  Bulletin  257,  page  20. 

1  See  Table  70  for  effect  of  plant  food  on  permanent  grass  park  more  than  250 
years  old.  — C.  G.  H. 


3i8       SYSTEMS   OF   PERMANENT   AGRICULTURE 

5.  "I  have  attempted  to  show  you  the  way  I  believe  fertilizers  act  and  the 
reason  we  use  them.    I  think  that  this  is  the  way  stable  manure  and  green 
manures  act.    I  think  that  is  the  principal  office  of  nitrate  of  soda,  potash,  and 
phosphoric  acid ;  but  they  do  not  all  act  alike  on  the  same  soils.    We  are  work- 
ing now  on  a  soil  in  Iowa  which  with  stable  manure  every  time  produces  a 
smaller  crop  than  without.  .  .  . 

6.  "There  is  another  way  in  which  the  fertility  of  the  soil  can  be  maintained, 
viz.,  by  arranging  a  system  of  rotation  and  growing  each  year  a  crop  that  is  not 
injured  by  the  excreta  of  the  preceding  crop;  then  when  the  time  comes  round 
for  the  first  crop  to  be  planted  again,  the  soil  has  had  ample  time  to  dispose  of 
the  sewage  resulting  from  the  growth  of  the  plant  two  or  three  years  before." 

—  WHITNEY,  in  Farmers'  Bulletin  257,  page  21. 

7.  "The  soil  solution  is  bringing  materials  from  below  which  the  plant  gets, 
and  as  a  matter  of  fact  the  most  important  discovery  of  the  Bureau  of  Soils  in 
recent  years  is  that  plants  are  feeding  on  materials  from  the  subsoils,  far  below 
where  the  roots  go." 

—  CAMERON,  in  the  Hearings  before  the  Committee  on  Agriculture  of  the 

United  States  House  of  Representatives,  page  446  (1908). 

8.  The  Chairman.    "Then  I  come  back  again  to  the  question,  Why  is  it 
necessary,  or  is  it  in  your  judgment  necessary,  ever  at  any  time  to  introduce 
fertilizing  material  into  any  soil  for  the  purpose  of  increasing  the  amount  of 
plant  food  in  that  soil?" 

Mr.  Cameron.  "Not  in  my  judgment." 

—  Hearings  before  the  Committee  on  Agriculture  of  the  United  States  House 

of  Representatives,  page  446  (1908). 

9.  "  In  the  truck  soils  of  the  Atlantic  coast,  where  10  or  15  tons  of  stable 
manure  are  annually  applied  to  the  acre,  in  the  tobacco  lands  of  Florida,  and  of 
the  Connecticut  Valley,  where  2000  or  3000  pounds  of  high-grade  fertilizers 
carrying  10  per  cent  of  potash  are  used,  even  when  these  applications  have  been 
continued  year  after  year  for  a  considerable  period  of  time,  the  dissolved  salt 
content  of  the  soil  as  shown  by  this  method  is  not  essentially  different  from  that 
in  surrounding  fields  that  have  been  under  extensive  cultivation. 

"In  England  and  in  Scotland  it  is  customary  to  make  an  allowance  to  tenants 
giving  up  their  farms  for  the  unused  fertilizers  applied  in  the  previous  seasons. 
The  basis  of  this  is  usually  taken  from  30  to  50  per  cent  for  the  first  year,  and  at 
10  to  20  per  cent  for  the  second  year  after  application,  but  in  the  experience  of 
this  Bureau  there  is  no  such  apparent. continuous  effect  of  fertilizers  on  the 
chemical  constitution  of  the  soil." 

-  WHITNEY  and  CAMERON,  in  Bureau  of  Soils  Bulletin  22,  page  59. 

The  question  may  be  asked  if  the  plant  food  brought  to  the  sur- 
face by  capillary  moisture  in  humid  sections  is  greater  than  that 
lost  by  leaching.  Compare,  for  example,  the  composition  of  the 
old  prairie  soil  (gray  silt  loam)  in  the  lower  Illinoisan  glaciation 


THEORIES    CONCERNING   SOIL   FERTILITY       319 

and  the  more  recent  prairie  soil  (brown  silt  loam)  of  the  late  Wis- 
consin glaciation.  Compare  also  the  amounts  in  the  surface  and 
subsoil  (in  2  million  pounds  of  each)  of  potassium  or  any  other  ele- 
ment which  does  not  accumulate  in  plant  residues.  Note  whether 
the  calcium  carbonate  on  Broadbalk  and  Hoos  fields  at  Rothamsted 
is  steadily  accumulating  at  the  surface.  There  are  abundant  sup- 
plies in  the  subsoil  "  far  below  where  the  roots  go."  Note  the  com- 
plete absence  of  calcium  carbonate  in  very  many  Illinois  soils. 
(See  also  Tables  4,  5,  and  21  in  the  preceding  pages.) 

Attention  is  called  to  the  fact  that  nitrification  is  a  process  of 
biochemical  action  and  not  one  of  mere  solution.  Director  Hall 
of  the  Rothamsted  Experiment  Station  makes  the  following 
statement  in  his  "Fertilizers  and  Manures"  (1909),  page  288. 

"  When  the  Rothamsted  soils,  with  their  long-continued  differences  in 
fertilizer  treatment,  are  extracted  with  water  charged  with  carbon  dioxide  — 
the  nearest  laboratory  equivalent  to  the  actual  soil  water  —  the  amount  of 
phosphoric  acid  going  into  solution  is  closely  proportional  to  the  previous 
fertilizer  supply,  and  this  proportionality  is  maintained  if  the  extraction  is 
repeated  with  fresh  solvent,  as  must  be  the  case  in  the  soil." 

It  should  be  kept  in  mind,  of  course,  that  a  one-crop  system 
followed  year  after  year  upon  the  same  land  usually  encourages  the 
growth  of  certain  weeds  whose  "  habits  "  are  similar  to  those  of 
the  crop  grown,  that  it  also  tends  toward  the  breeding  of  insect 
enemies  and  to  the  development  of  fungous  diseases  peculiar  to 
that  crop,  such  as  "  flax  sickness,"  investigated  by  the  North  Da- 
kota Experiment  Station,  and  "  clover  sickness,"  which  has  long 
been  thought  to  be  an  actual  fact  in  practical  agriculture,  concern- 
ing which  the  Tennessee  Station  has  recently  reported  some  prom- 
ising results.  The  legume  plants  appear  to  be  especially  suscep- 
tible to  such  fungous  diseases,  the  cowpea  wilt  being  well  known, 
and  "  bean-sick  "  soil  is  a  common  expression.  It  seems  probable 
that  bacterial  as  well  as  fungous  diseases  may  develop  under  suit- 
able conditions. 

While  it  is  possible  that  inanimate  toxic  substances  may  also 
be  formed  in  the  soil  from  possible  plant  excreta,  or  less  improb- 
ably from  the  decomposition  of  the  crop  residues,  there  is  no  knowl- 
edge or  evidence  sufficient,  in  the  author's  opinion,  to  justify  a 
theory  that  fertilizers  act  primarily  as  antitoxins.  It  should  be 


320       SYSTEMS    OF   PERMANENT   AGRICULTURE 

remembered  that  well-fed  plants  are  usually  better  able  to  resist 
or  overcome  the  attacks  of  insects  and  diseases.  It  is  well  known 
that  there  are  some  exudations  from  germinating  seeds,  and  it 
seems  evident  that  water  used  repeatedly  for  2O-day  cultures  with 
'seedling  plants  becomes  stagnant,  putrid,  or  toxic,  but  can  we 
correlate  this  with  field  conditions? 

Alkaline  slag  phosphate,  acidulated  rock  phosphate,  neutral 
steamed  bone  meal,  and  insoluble  raw  rock  phosphate  are  very 
different  chemical  substances,  and  the  very  complete  data  already 
presented  show  that  any  one  of  these  forms  of  phosphorus  may  be 
used  to  increase  crop  yields.  Sodium  nitrate,  ammonium  sulfate, 
and  dried  blood  are  exceedingly  different  substances,  but  they  all 
contain  nitrogen,  and  where  nitrogen  is  deficient  in  the  soil,  any 
one  of  these  materials  will  benefit  the  crop.  Moreover,  with  legume 
plants,  essentially  the  same  results  are  secured  whether  nitrogen  is 
supplied  in  dried  blood  or  provided  by  the  nitrogen-fixing  bacteria 
without  fertilizer  application. 

It  may  be  noted  that  while  Whitney  and  Cameron  in  Bulletin  22 
(1903),  of  the  Bureau  of  Soils,  included  nitrogen  as  distinctly  as 
phosphorus,  potassium,  and  calcium,  as  being  contained  in  prac- 
tically all  soils  in  an  ample  supply  which  "  will  be  indefinitely 
maintained,"  and  while  Professor  Whitney  also  asserts,  in  Farmers' 
Bulletin  257  (1906),  that  the  correction  of  toxic  substances  is 
"  the  principal  office  of  nitrate  of  soda,  potash,  and  phosphoric 
acid,"  and  while  Cameron  admits  in  the  Hearings  before  the  Com- 
mittee on  Agriculture  (1908)  that  it  is  never  necessary  at  any  time 
to  introduce  fertilizing  material  into  any  soil  for  the  purpose  of 
increasing  the  amount  of  plant  food  in  that  soil;  nevertheless, 
Whitney  and  Cameron  are  beginning  to  qualify  their  theories  by 
saying  "  mineral  elements  "  or  "  mineral  plant  food,"  presumably 
because  the  mathematical  opposition  is  too  strong,  considering 
that  the  soil  contains  but  very  small  amounts  of  nitrogen  "  far 
below  where  the  roots  go." 

On  December  9,  1908,  the  National  Conservation  Commission 
presented  its  report  (prepared  for  the  President)  to  the  Conference 
of  Governors  and  State  Conservation  Commissioners  assembled 
in  Washington,  in  which  great  emphasis  was  laid  upon  the  impor- 
tance of  conserving  the  supply  of  natural  phosphates,  as  a  result 


THEORIES    CONCERNING   SOIL   FERTILITY       321 

of  which  the  President  soon  afterward  withdrew  from  entry  the  re- 
maining government  lands  that  were  known  to  contain  phosphate 
deposits,  acting  upon  the  advice  of  the  United  States  Geological 
Survey  and  the  National  Conservation  Commission;  while  on 
December  10,  1908,  the  daily  press  of  the  country  very  generally 
published  a  Washington  dispatch  headed  "  SOIL  WON'T  WEAR 
OUT,"  in  which  Professor  Whitney  was  credited  with  the  following 
statements : 

"There  is  a  general  impression  among  economists  that  soil  fertility  is  declin- 
ing through  loss  of  mineral  plant  food,  but  the  Bureau  of  Soils,  through  the 
extensive  soil  surveys  and  investigations  made  in  the  laboratories  and  from  the 
study  of  world-wide  records,  has  determined  that  this  impression  of  the  decline 
of  soil  fertility  is  erroneous. 

"It  is  not  unreasonable  to  expect  that  as  this  country  becomes  more  thickly 
settled  and  our  people  are  forced  to  cultivate  smaller  areas,  with  more  intelli- 
gent and  more  intensive  methods,  the  actual  amount  of  crops  obtained  from 
the  land  now  in  crops  can  be  increased  two  and  one  half  times  over  what  we 
are  now  producing. 

"But  the  amount  of  land  in  crops  is  only  about  one  fourth  of  the  amount  in 
farms.  Applying  this  ratio  to  the  whole  amount  in  farms,  it  is  apparent  that, 
the  land  in  farms  at  present  can  be  expected  to  produce  in  time  something  like 
ten  or  twelve  times  the  amount  of  crops  that  are  now  produced  on  these  farms. 

"So  far  as  the  present  outlook  is  concerned,  the  nation  possesses  ample 
resources  in  its  soils  for  any  conceivable  increase  in  population  for  several 
centuries. 

"The  Bureau  of  Soils  finds  that  the  decline  in  yield  is  due  generally  to  the 
accumulation  of  organic  products  in  the  soil  which  are  not  eliminated  through 
proper  cultural  methods  as  fast  as  they  have  accumulated,  and  that  the  failures 
that  are  reported  are,  therefore,  due  to  improper  methods  of  cultivation  and 
crop  rotation. 

"Our  own  government  statistics  show  that  during  the  last  forty  years  the 
yields  per  acre  of  all  our  cereal  crops  have  shown  a  tendency  to  increase.  Statis- 
tics of  all  the  European  countries  show  that  the  yields  in  recent  years  have  con- 
sistently increased." 

Of  course  this  press  dispatch  would  not  be  quoted  here  except 
that  it  is  in  strict  accord  with  the  persistent  teaching  of  Whitney 
and  Cameron,  which  will  be  found  of  greatest  interest  for  compari- 
son with  that  of  Jethro  Tull  or  Doctor  Hunter,  and  with  Liebig's 
nitrogen  theory. 

Since  the  above  was  written,  Bulletin  55  of  the  Bureau  of  Soils, 
"  Soils  of  the  United  States,"  by  Milton  Whitney,  has  been  pub- 


322 

lished  (February,  1909),  from  which  the  following  statements  are 
quoted : 

"The  soil  is  the  one  indestructible,  immutable  asset  that  the  nation  possesses. 
It  is  the  one  resource  that  cannot  be  exhausted;  that  cannot  be  used  up.  The 
general  conception  of  the  exhaustion  of  soils  is  that  the  crop  removes  plant  food, 
and  that  unless  we  return  some  considerable  portion  of  plant  food  to  the  soil  it 
eventually  becomes  incapable  of  longer  producing  adequate  crops.  We  quote 
from  a  recent  article  in  one  of  the  agricultural  journals: 

"  '  We  have  warned  our  readers  for  the  last  ten  years  of  what  is  coming  if 
they  continue  to  grow  grain  crops  and  sell  them  off  the  farm  continuously  from 
year  to  year.  .  .  .  Don't  imagine  for  one  minute  that  your  soils  are  of  inexhaust- 
ible fertility.  No  such  soils  were  ever  made  in  the  Western  Hemisphere,  except, 
perhaps,  such  as  are  enriched  by  overflow  every  three  or  four  years.' 

"The  impression  prevails  that  our  crops  take  out  phosphoric  acid,  potash, 
and  nitrates  to  such  an  extent  that  the  soil  becomes  incapable  of  longer  supply- 
ing these  plant-food  constituents  for  a  satisfactory  yield." 

"As  we  see  it  now,  the  main  cause  of  infertile  soils  or  the  deterioration  of 
soils  is  the  improper  sanitary  conditions  originally  present  in  the  soil  or  arising 
from  our  injudicious  culture  and  rotation  of  crops.  It  is,  of  course,  exceedingly 
difficult  to  work  out  the  principles  which  govern  the  proper  rotation  for  any  par- 
ticular soil.1 

"The  important  thing  is  that  we  now  understand  the  nature  of  the  soil;  how 
it  supplies  the  nutrient  constituents  for  the  crops  and  how  it  maintains  the  supply ; 
how  crops  may  affect  each  other  when  grown  in  succession  on  the  soil ;  how  cul- 
tivation affects  the  conditions  resulting  from  the  crop,  and,  lastly,  we  are  begin- 
ning to  understand  how  fertilizers  come  into  this  scheme  and  themselves  act  on 
or  change  toxic  conditions  in  the  soil,  rendering  the  soil  again  sweet  and 
healthy  for  the  growing  crop." 

"It  has  been  shown  that  in  southern  Maryland  and  in  middle  Virginia  the 
cause  of  the  recent  depression  in  agriculture  and  of  the  low  yield  of  crops  is  due 
to  methods  which  have  prevailed  rather  than  to  any  exhaustion  of  the  soil, 
and  that  with  improved  methods  these  areas  are  coming  up  and  will  again  be 
made  to  produce  satisfactory  crops.  The  soils  are  not  wearing  out  in  the  sense 
that  they  are  unable  longer  to  provide  mineral  nutrients,  but  the  yields  are  low 
because  through  the  prevailing  methods  the  soils  have  not  been  maintained  in 
proper  condition.  In  these  latter  instances  the  yields  have  actually  declined, 
but  not  from  the  cause  which  has  been  generally  ascribed. 

"It  has  been  shown  that  from  the  modern  conception  of  the  nature  and  pur- 
pose of  the  soil  it  is  evident  that  it  cannot  wear  out,  that  so  far  as  the  mineral 
food  is  concerned,  it  will  continue  automatically  to  supply  adequate  quantities 
of  the  mineral  plant  foods  for  crops,  but  it  has  also  been  shown  that  the  soil 
can  be  abused  and  its  fertility  temporarily  impaired  by  improper  methods  of 
handling. 

1  Italics  mine.  — C.  G.  H. 


THEORIES    CONCERNING   SOIL   FERTILITY       323 

"Lastly,  it  has  been  shown  from  the  statistics  of  European  countries  that  the 
soils  of  the  world  are  not  wearing  out,  but  that,  on  the  contrary,  after  a  thousand 
years  of  cultivation,  With  the  introduction  of  better  methods,  with  the  necessity 
of  raising  larger  crops,  these  soils  are  responding  with  an  increased  yield  even 
over  what  they  produced  at  the  beginning  of  the  last  century. 

"As  a  national  asset  the  soil  is  safe  as  a  means  of  feeding  mankind  for  untold 
ages  to  come.  So  far  as  our  investigations  show,  the  soil  will  not  be  exhausted 
of  any  one  or  all  of  its  mineral  plant-food  constituents.  If  the  coal  and  iron 
give  out,  as  it  is  predicted  that  they  will  before  long,  the  soil  can  be  depended  on 
to  furnish  food,  light,  heat,  and  habitation  not  only  for  the  present  population, 
but  for  an  enormously  larger  population  than  the  world  has  at  present." 

This  general  outline  of  soil-fertility  theories  has  been  introduced 
at  this  point  in  order  that  the  reader  may  note  their  application 
in  the  following  pages;  and  it  is  hoped  that  the  preceding  and  suc- 
ceeding data  are  sufficient  to  enable  him  to  form  his  own  opinion. 

It  is  well  to  keep  in  mind  a  few  general  facts:  e.g.,  that  the  total 
corn  acreage  of  Rhode  Island  and  Connecticut  combined  averages 
less  than  three  townships  (about  one  sixth  of  one  average  Illinois 
county,  of  which  there  are  102);  that  the  total  corn  acreage  of 
Maine,  New  Hampshire,  Vermont,  Massachusetts,  Connecticut, 
Rhode  Island,  New  York,  New  Jersey,  Pennsylvania,  Delaware, 
and  Maryland,  all  combined,  is  less  than  the  average  corn  acreage 
of  Georgia,  whose  ten-year  average  yield  is  u  bushels  per  acre, 
and  less  than  one  half  the  corn  acreage  of  Illinois;  that  Illinois 
produces  the  same  amount  of  corn  per  annum  as  the  aggregate 
production  of  the  six  New  England  states,  the  six  Middle 
Atlantic  states,  and  the  six  South  Atlantic  and  Gulf  states  — 
eighteen  in  all  —  extending  from  Maine  to  the  mouth  of  the 
Mississippi,  although  Georgia,  one  of  these  states,  is  larger  than 
Illinois ;  that  during  the  last  ten  years  the  average  corn  acreage 
of  Illinois  has  been  increased  from  7  million  to  10  million  acres 
by  putting  under  cultivation  old  blue-grass  pastures  and  drained 
swamp  areas  representing  the  richest  soil  of  the  state;  that  in  the 
Eastern  states  manure,  made  in  part  from  food  stuffs  shipped 
from  the  newer  states,  is  worth  about  $2  a  ton;  that  level 
or  gently  undulating  farm  lands  in  Maryland  and  Virginia  sell 
for  less  than  $5  an  acre,  while  those  of  Illinois  and  Iowa  are 
worth  $100  or  $200;  that,  while  England  produces  32  bushels  of 
wheat  per  acre  with  a  total  production  of  50  million  bushels, 


324       SYSTEMS   OF   PERMANENT   AGRICULTURE 

England  imports  200  million  bushels  of  wheat,  100  million  bushels 
of  corn,  nearly  a  billion  pounds  of  oil  cake,  and  much  phosphate 
and  other  fertilizing  material;  that  Germany  produces  125 
million  bushels  of  wheat,  and  in  addition  imports  75  million 
bushels  of  wheat,  40  million  bushels  of  corn,  a  billion  pounds 
of  oil  cake,  and  much  phosphate,  etc.,  and  that  Germany's  chief 
export  is  2  billion  pounds  of  sugar  (C12H22OU);  that  Den- 
mark produces  4  million  bushels  of  wheat,  imports  5  million 
bushels  of  wheat,  15  million  bushels  of  corn,  800  million  pounds 
of  oil  cake,  phosphates,  etc.,  and  exports  175  million  pounds  of 
butter;  that  Belgium  produces  12  million  bushels  of  wheat  and 
imports  60  million  bushels,  etc. 

It  is  interesting  also  to  keep  in  mind  the  following  statement1  by 
Doctor  Bernard  Dyer  in  his  American  lectures  on  "  Results  of 
Investigations  on  the  Rothamsted  Soils,"  in  connection  with  his 
discussion  of  the  Broadbalk  wheat  plot  that  has  received  an  annual 
application  of  15.7  tons  of  farm  manure  since  1844: 

"It  is  to  be  borne  in  mind,  however,  that  the  quantity  of  dung  used  in  these 
continuous  wheat-growing  experiments  is,  on  the  yearly  average,  far  less  than 
would  be  used  in  practical  agriculture  on  any  of  the  rotation  systems." 

As  early  as  1855,  England  was  importing  annually  more  than 
200,000  tons  of  guano  from  the  west  coast  of  South  America  and 
from  the  islands  of  the  sea.  The  guanos  vary  in  composition  from 
about  15  per  cent  of  nitrogen  and  5  per  cent  of  phosphorus  to  less 
than  i  per  cent  of  nitrogen  and  more  than  1 5  per  cent  of  phosphorus. 

Aikman  writes  in  "Manures  and  the  Principles  of  Manuring" 
(1894)  as  follows  concerning  the  use  of  bones  in  England: 

(  "Employed  first  in  1774,  their  use  has  steadily  increased  ever  since,  and  their 
popularity  as  a  phosphatic  manure  is  among  farmers  in  this  country  quite  un- 
rivaled. .  .  .  Soon  their  use  became  so  popular  that  the  home  supply  was  found 
inadequate.  .  .  .  So  largely  were  they  used  by  English  farmers  that  Baron  Liebig 
considered  it  necessary  to  raise  a  warning  protest  against  their  lavish  applica- 
cation :  '  England  is  robbing  all  other  countries  of  the  condition  of  their  fertility. 
Already  in  her  eagerness  for  bones  she  has  turned  up  the  battlefields  of  Leipzig, 
of  Waterloo,  and  of  the  Crimea ;  already  from  the  catacombs  of  Sicily  has  she 
carried  away  the  skeletons  of  many  successive  generations.  Annually  she 
recovers  from  the  shores  of  other  countries  to  her  own  the  manurial  equivalent 
of  three  millions  and  a  half  of  men.')" 

1  Page  50,  Bulletin  106,  Office  of  Experiment  Stations,  United  States  Depart- 
ment of  Agriculture. 


THEORIES  CONCERNING   SOIL   FERTILITY       325 

Aikman  states  that  at  the  present  time  about  100,000  tons  of 
bones  are  used  annually  on  English  soils,  and  that  bone  ash  is 
still  imported  from  South  America.  The  East  Indians  complain 
that  England  has  robbed  India  of  bones. 

The  importation  of  mineral  phosphates  into  England  exceeded 
250,000  tons  in  1885,  when  more  than  a  dozen  countries  were  being 
drawn  upon  for  this  material,  representing  three  continents  and 
Australia;  and  as  early  as  1892  the  United  States  was  furnishing 
Great  Britain  more  than  200,000  tons  of  phosphate  a  year. 

Besides  this,  England  has  her  own  phosphate  deposits  in  the  form 
of  coprolites  or  phosphatic  nodules,  which,  according  to  Aikman, 
"  have  been  found  in  great  abundance  in  the  greensand  formation, 
in  the  crag  of  the  eastern  counties,  and  in  the  chalk  formations  of 
the  southern  counties."  He  adds: 

"They  are  found  in  large  quantities  in  Cambridgeshire.  .  .  .  They  were  also 
found  in  enormous  quantities  in  Suffolk,  Norfolk,  Bedfordshire,  and  Essex, 
and  were  for  a  long  time  largely  used  in  the  manufacture  of  superphosphate 
(acid  phosphate),  but  of  late  years  have  not  been  used  to  anything  like  the  same 
extent,  owing  to  the  fact  that  there  are  richer  and  cheaper  sources  of  phosphate 
of  lime  available;" 

In  addition  to  all  this,  England  produces  and  supplies  to  her 
soils  large  quantities  of  slag  phosphate,  the  amount  of  which  ex- 
ceeded 100,000  tons  a  year  before  the  close  of  the  last  century, 
and  her  annual  production  has  since  risen  to  300,000  tons  per 
annum. 

France,  Germany,  and  other  small  European  countries  are  not 
far  behind  England  in  the  matter  of  increasing  the  fertility  of  their 
soils.  By  1890  France  was  using  about  400,000  tons  of  phosphate 
annually,  and  this  was  supplemented  by  slag  phosphate,  the  amount 
of  which  exceeded  200,000  tons  in  1899,  while  Germany  applied 
800,000  tons  of  slag  phosphate  to  her  soils  the  same  year.  The 
application  of  phosphates  to  the  soils  of  Europe  has  largely  in- 
creased during  the  years  of  the  present  century.  Thus,  in  1907, 
Italy,  with  a  total  area  of  less  than  115,000  square  miles  (about 
twice  as  large  as  Illinois),  used  950,000  metric  tons  of  phosphate 
(also  82,000  tons  of  nitrogen  fertilizer,  and  7000  tons  of  potassium 
salts;  and  during  the  five  years,  1904  to  1908,  more  than  i| 
million  long  tons  of  Florida  phosphate  were  shipped  to  Germany. 


326       SYSTEMS    OF   PERMANENT   AGRICULTURE 

Since  the  promulgation  of  much  definite  knowledge  during  the 
first  half  of  the  last  century,  by  such  teachers  as  De  Saussure,  Davy, 
Bousingault,  Liebig,  and  Lawes  and  Gilbert,  the  increasing  appli- 
cations of  phosphates,  manures  made  in  part  from  imported  food 
stuffs,  and  other  fertilizing  materials,  including  more  or  less  po- 
tassium salts  and  nitrates,  and  in  more  recent  years  a  larger  use  of 
legumes,  are  found  to  bear  fruit  in  the  corresponding  increase  in 
the  crop  yields  of  western  Europe,  as  will  be  seen  from  the  follow- 
ing crop  statistics,  compiled  by  Professor  Wilhelm  Kellerman 
(Landwirtschaftliches  Jahrbuch,  1906,  page  289)  and  republished 
by  the  United  States  Bureau  of  Soils  (Bulletin  55)  for  the  purpose 
of  showing  that  soils  do  not  wear  out. 

The  data  from  Schmatzfeld  are  of  interest  because  of  the  old 
records,  but  they  appear  to  represent  in  the  main  single  years, 
and  in  part  selected  years.  Even  the  tenth-year  records  from  1830 
to  1870  may  signify  but  little.  Thus  the  rye  and  oats  for  1870 
average  less  than  for  1830.  The  late  averages  are,  of  course,  very 
significant. 

The  Trebsen  records  have  much  value  because  they  include 
several  ic-year  averages  which  show  no  advancement  prior  to  the 
publication  of  De  Saussure's  work,  which  gave  to  the  world  the 

YIELDS  OF  CEREALS  IN  SCHMATZFELD,  GERMANY 


YEAR 

WHEAT 
(Bu.) 

RYE 
(Bu.) 

BARLEY 
(Bu.) 

OATS 
(Bu.) 

iC'?2-i';<;7    . 

12   < 

T  7   ? 

T/l    9 

14  8 

1660    

i6--* 

12  8 

8  3 

1670    . 

14  6 

172 

°-6 
16  i 

"•j 

T7  A 

1822    

18  7 

I/.  4 

182^ 

18  i 

^4-J 

66-  1 
28  I 

TO  e 

1870    . 

18  7 

?r  g 

3a-5 

1840    

2C  6 

OJ-U 

AC    C 

i8<;o    . 

28  7 

Jl.U 

45o 
Cn  T 

1860    

•3C     -7 

66-  L 

3v-o 

5°'4 

1870    

27  6 

6y-o 

3^-y 

/tc  8 

/ifi  fi 

1886    

77  O 

28  9 

4:>-0 

fifi  f\ 

1887-1896    . 

43  •  •* 

1897-1904    .... 

46  I 

59-7 

5°-4 

THEORIES    CONCERNING    SOIL   FERTILITY       327 

YIELDS  OF  CEREALS  ON  RITTERGUT  TREBSEN,  NEAR  LEIPZIG 


YEAR 

WHEAT 
(Bu.) 

RYE 
(Bu.) 

BARLEY 
(Bu.) 

OATS 
(Bu.) 

I766—I  77  "? 

13.  2t; 

12.33 

21.71 

23.48 

1776-1785     
1  736-1  7(K      . 

16.63 
13.98 

14.47 
13.67 

20.44 
l6.77 

23-45 
IQ.l6 

1  796—1800     

13.89 

IS-  16 

I5.l6 

17.00 

1814-1816     

15.28 

15.68 

2^.41 

2<C.  72 

1820—1822     

16.00 

19.14 

18.28 

26.36 

i82<;-i834    , 

21.04 

21.63 

3O.I9 

31.83 

l83<-l844     , 

77.40 

27.92 

36.66 

46X4 

/•>8   -- 

i»45  1049    
1883-1892    

25-51 
27.03 

2°-75 
23.06 

3O.95 

56-25 
44.64 

1803-1804    , 

29.81: 

28.36 

3O.95 

54-74 

180^—1800    . 

35.85 

30.45 

35-3Q 

51.15 

i  000—1004    , 

36.14 

32.52 

43.23 

57.80 

YIELDS  OF  CEREALS  ON  ANOTHER  GERMAN  ESTATE 


1800-1810     

21.15 

14.64 

19.80 

17.22 

1810—1820     

20.02 

11.76 

20.92 

17.44 

1820-1830    
1830-1840    
1840—1850     

23-25 
18.82 

23.10 

17.76 

15.04 

10.84 

21.29 

16.37 

20.87 

14.84 
13.86 
27.58 

1850-1855  
1855-1860    

26.40 
25.  27 

23.12 

24.16 

32-75 

27.71 

33-46 

34-44 

1860-1865    

29.77 

30.48 

37.85 

44.52 

1865-1870    

27.45 

26.48 

36.17 

55.72 

1870-1875    
1875-1880    

29.92 

28.12 

28.32 

24,72 

35-71 
29.38 

51-38 

7O.48 

1880-1885   
1885-1894    

25-57 

3^.70 

25.12 

20.^2 

36.45 

41.06 

45.08 
43.06 

AVERAGE  YIELDS  OF  CEREALS  IN  GERMANY 


1881-1885    

21.7? 

18.56 

20.07 

36.06 

1886-1890    

22.6=C 

IQ.O4 

20.07 

40.42 

i8oi-i8(X 

2A.7O 

21.28 

2I.SJ4 

40.88 

I896—I9OO        

26."^ 

23.04 

32.49 

45.  08 

AVERAGE  YIELDS  OF  CEREALS  IN  FRANCE 


1815-1824    

11.86 

IO.IO 

14.  4C 

17.12 

1825-1834 

13.44 

12.34 

14.64 

17.78 

1835-1844    , 

14.30 

I3.OI 

1^-02 

2O.  IO 

1855-1864    

I  ^  QO 

14  II 

10  QO 

24.03 

1865-1874 

I5.8l 

14  6< 

IQ.7S 

24.40 

1875-1876    . 

1  6.  60 

1^.71 

IQ.OO 

23.6l 

328        SYSTEMS    OF   PERMANENT   AGRICULTURE 

first  definite  information  which  could  serve  as  a  scientific  basis 
for  systems  of  soil  improvement.  The  few  records  from  1800  to 
1825  are  of  little  or  no  value,  but  the  averages  from  1825  to  1834 
show  very  clearly  the  application  of  definite  knowledge  as  com- 
pared with  the  averages  previous  to  1800;  while  the  further  marked 
increase  for  the  ten  years  ending  1844  clearly  shows  that  the  teach- 
ings of  Davy,  Bousingault,  and  Liebig  were  being  applied  on  the 
Trebsen  estate  as  well  as  by  Sir  John  Lawes  at  Rothamsted. 

The  most  satisfactory  data  are  from  the  third  German  estate, 
showing  lo-year  or  5-year  averages  for  practically  all  of  the  last 
century,  from  which  it  is  plain  to  see  that  the  first  distinct  increases 
date  from  the  publication  of  Liebig's  teachings  in  1840. 

While  the  larger  private  estates  would  perhaps  be  the  first  to 
adopt  the  teachings  of  science,  the  records  show  general  increases 
for  both  Germany  and  France.  The  average  yields  of  wheat  of 
late  years  for  England,  Germany,  and  France  are  32.2,  28.0,  and 
19.8  bushels  per  acre,  respectively,  or,  as  a  general  average,  about 
double  the  average  of  100  years  ago.  It  is  safe  to  credit  this  in- 
crease very  largely  to  the  use  of  plant  food,  including  the  more 
general  use  of  atmospheric  nitrogen  by  legume  crops  during  the 
last  quarter  century.  The  average  yield  of  wheat  in  the  United 
States  is  13.7  bushels  for  the  ten  years,  1899  to  1908. 

A  second  factor1  of  much  importance  in  crop  improvement, 
though  very  subordinate  to  that  of  plant  food,  is  the  improvement 
in  seed  by  selection  and  breeding.  A  German  economist  has  esti- 
mated that,  as  an  average,  seed  improvement  has  produced  a 
gain  of  25  per  cent.  In  exceptional  cases,  as  with  the  sugar  beet, 
very  remarkable  progress  has  been  made  by  breeding,  the  average 
sugar  content  of  the  beet  having  been  raised  from  about  4  per  cent 
to  12  per  cent  or  more. 

The  following  extracts  from  an  address  by  President  Creelman, 
of  the  Ontario  Agricultural  College,  to  the  Ontario  Agricultural 
and  Experimental  Union,  December,  1908,  is  well  worthy  of  care- 
ful consideration  (Report  for  1908,  page  62) : 

1  Other  factors  of  improvement  are  of  doubtful  consequence,  including  correc- 
tion of  toxic  bodies.  Tillage  and  crop-rotation  have  been  the  rule  for  centuries  in 
old  countries.  Isolation  of  such  bodies  signifies  little.  The  soil  is  earth's  waste- 
basket,  wherein  we  may  find  almost  every  substance,  toxic  or  nontoxic. 


THEORIES    CONCERNING   SOIL   FERTILITY       329 

"SOME  OBSERVATIONS  OF  FARMING  IN  SOUTHERN  EUROPE 

"Italy  has  been  practicing  the  art  of  agriculture  since  the  early,  early  days 
of  the  old,  old  civilization,  hundreds  of  years  before  the  Christian  era  began, 
and  agriculture  is  still  the  most  important  industry  in  Italy,  as  85  per  cent  of  all 
the  Italian  soil  is  productive  land.  Dairying  is  not  one  of  the  leading  lines, 
however,  nor  is  any  other  kind  of  stock  raising.  Oxen  and  asses  are  still  the 
principal  beasts  of  burden,  and  wine  the  largest  crop. 

"And  yet,  the  agricultural  products  of  Italy  are  varied,  and  in  the  aggregate 
amount  to  a  very  large  total.  Remember  that  Italy  is  only  twice  the  size  of  the 
State  of  New  York,  and  you  will  realize  that  not  much  land  is  wasted  when  the 
following  crops  are  produced  annually: 

Wheat 143,400,000  bushels 

Corn 85,600,000  bushels 

Oats 19,360,000  bushels 

Rye  and  barley 18,400,000  bushels 

Rice 26,000,000  bushels 

Other  cereals       18,000,000  bushels 

Total  cereals 310,760,000  bushels 

Potatoes 19,360,000  bushels 

Hemp 111,000,000  pounds 

Flax 30,000,000  pounds 

Cotton    .< 22,000,000  pounds 

Tobacco 7,250,000  pounds 

Olive  oil 74,500,000  gallons 

Wine 666,000,000  gallons 

"But,  like  the  Swiss  and  the  French,  the  peasant  people  are  a  frugal,  thrifty 
race ;  and  while  the  rich  eat  wheat  bread,  the  work-people  are  content  with 
bread  made  from  corn  or  rye. 

"Legumes  everywhere.  In  looking  about  to  find  how  the  fertility  of  the 
soil  was  maintained,  in  districts  where  live  stock  was  not  common,  and  hence 
farm  manure  was  far  from  plentiful,  I  noticed  that  everywhere  leguminous  crops 
(or  pulse)  were  the  rule.  I  also  discovered  that  in  some  form  it  was  eaten  every, 
day  by  rich  and  poor  alike.  All  the  time  I  was  in  Italy  I  never  once  sat  down 
to  a  dinner  without  being  served  with  peas  or  beans  or  lentils,  or  some  other 
variety  of  leguminous  annual.  I  found  also  that  the  poorer  classes  consume 
large  quantities  of  pulse,  it  being  used  to  a  large  extent  as  a  substitute  for  meat." 

The  increases  in  these  European  crop  yields  since  about  1825  to 
1840  should  be  a  most  effective  object-lesson  to  the  American  farmer 
to  "  go  and  do  likewise  ";  and  if  he  will  talk  with  any  man  who 
has  had  experience  in  western  European  agriculture  during  the 
last  quarter  century,  he  will  promptly  receive  the  positive  assur- 


33° 


SYSTEMS   OF   PERMANENT   AGRICULTURE 


ance  that  no  successful  farmer  in  those  countries  thinks  of  trying 
to  farm  without  liberal  applications  of  plant  food,  especially  of 
phosphate  fertilizers,  and,  as  a  rule,  either  farm  manure  or  green 
manure.  Often  commercial  nitrogen  and  potassium  are  also 
used,  in  part  because  of  the  very  high  value  of  farm  produce  and 
also  because  of  the  low  price  of  potassium  salts,  Germany's  supply 
of  which  is  estimated  to  be  sufficient  to  meet  the  present  con- 
sumption of  the  world  for  190,000  years. 

In  comparison  with  these  European  records,  marked  contrast 
appears  in  the  average  crop  yields  of  the  state  of  Kansas  during 
48  years.  Professor  W.  J.  Spillman,  of  the  United  States  Bureau 
of  Plant  Industry,  has  called  attention  to  these  statistics  in  the 
following  words: 

"The  following  table  of  figures  is  interesting: 

"YIELDS  PER  ACRE  —  AVERAGE  FOR  STATE  OF  KANSAS 


CROP 

1860-1889 

(Bu.) 

1880-1908 
(Bu.) 

DECREASE 
(Per  Cent) 

Corn    

T.A.2 

21  6 

-26.0 

Wheat      

1C.  2 

n.8 

22.8 

Oats    

12.8 

2I.O 

32.2 

"These  figures  are  in  general  agreement  with  data  collected  from  other 
sections  of  this  country.  When  rich  virgin  soil  is  brought  into  cultivation  and 
farmed  without  any  reference  to  the  conservation  of  fertility,  good  yields  are 
obtained  for  about  forty  years.  Then  begins  a  decline,  and  the  yield  ultimately 
sinks  down  to  a  point  where  there  is  no  profit  for  the  farmer.  ...  In  the  case 
of  each  of  the  three  crops  above  mentioned  the  average  yield  for  the  past  nine 
years  is  slightly  greater  than  for  the  preceding  ten  years.  This  indicates  that  the 
.  Kansas  farmer  is  slowly  but  surely  improving  his  system  of  farming.  Dairying 
and  the  feeding  of  beef  cattle,  also  hay  raising  are  becoming  more  prevalent, 
and  there  is  every  reason  to  believe  that  before  another  generation  has  passed 
the  Kansas  farmer  will  have  rehabilitated  his  soil  and  have  developed  suitable 
systems  of  farming  that  will  keep  Kansas  near  the  forefront  in  agriculture." 
(Hoard's  Dairyman,  May  14,  1909.) 

While  the  average  yields  are  probably  approximately  correct 
and  the  results  are  exceedingly  striking,  in  the  author's  opinion 
these  Kansas  results  have  little  significance,  because  of  the  enor- 
mous increase  and  westward  extension  of  the  area  put  under  cul- 


THEORIES    CONCERNING   SOIL   FERTILITY 


331 


tivation  in  Kansas  during  the  fifty  years,  as  briefly  indicated  by 
the  following  tenth-year  records: 

ACREAGE  OF  CEREALS  IN  KANSAS 


YEAR 

CORN 

WHEAT 

OATS 

1862       . 

17036^ 

O^6o 

2036 

1868       
1878       

360388 

240^482 

98525 

I  7  3081  2 

9880 
4441  QI 

1888       

600"?  20  7 

1120119 

16^6814 

1808 

7277601 

4624731 

KX4QOO 

IOCS 

7CK7<^c; 

60  30  'Kl 

8311^0 

When  we  consider  that  eastern  Kansas,  the  part  first  settled, 
is  in  the  humid  section  of  the  United  States,  and  that  the  later 
years  include  the  records  from  the  central  and  western  parts  of 
the  state  where  semiarid  conditions  prevail,  it  will  be  seen  that  the 
average  yields  computed  by  Professor  Spillman  may  serve  best  to 
illustrate  the  possibility  of  drawing  erroneous  conclusions  from  the 
use  of  general  statistics  unless  full  consideration  is  given  to  all 
important  factors.  The  explanation  for  the  slight  increase  in  the 
average  yields  of  the  last  nine  years  of  the  period,  as  compared 
with  the  preceding  ten  years,  is  very  possibly  to  be  found  in  the 
increased  rainfall  in  the  semiarid  region,  as  is  well  illustrated  by 
the  very  interesting  and  very  instructive  diagram  (shown  on  an- 
other page)  of  the  rainfall  record  at  North  Platte,  Nebraska,  for 
the  thirty-four  years,  1875  to  1908  (Nebraska  Bulletin  109,  April, 
1909),  from  which  it  will  be  seen  that  the  ten  years,  1890  to  1899, 
included  eight  years  below  normal  and  averaged  only  15.35  inches, 
while  the  following  nine  years,  1900  to  1908,  show  but  three  years 
below  normal,  and  average  21.21  inches. 

It  should  be  kept  in  mind  that  meat  and  dairy  products  bring 
much  larger  returns  in  Maryland  than  in  Kansas,  and  until  the 
well-situated,  well-drained,  and  well-wa'tered  farm  lands  of  Mary- 
land and  Virginia  have  been  rehabilitated  by  these  methods  of 
live-stock  farming  (which  farmers  have  been  familiar  with  for 
centuries) ;  until  such  soils  as  the  Leonardtown  loam,  comprising 
41  per  cent  of  St.  Mary  County,  Maryland,  where,  to  quote  the 


332        SYSTEMS   OF   PERMANENT   AGRICULTURE 

language  of  the  Bureau  of  Soils,  "  it  is  worth  from  $i  to  $3  an  acre," 
which  also  covers  45,770  acres  of  land  in  Prince  George  County, 
adjoining  the  District  of  Columbia,  where  it  "  can  be  bought  for 
$1.50  to  $5  an  acre,  even  within  a  few  miles  of  the  District 
line,"  -  until  this  Leonardtown  loam,  which,  according  to  Whit- 
ney's latest  decision  (Bureau  of  Soils  Bulletin  55,  page  116,  Febru- 
ary, 1909),  "  is  a  valuable  upland  soil  of  Maryland  and  Virginia; 
the  surface  is  slightly  rolling,  the  drainage  in  most  areas  good,  and 
altogether  the  land  is  well  suited  to  general  farming";  until  this 
land  which,  according  to  the  analyses  of  the  Bureau  of  Soils 
(Bulletin  54,  page  19),  contains  in  2  million  pounds  of  the  surface 
soil  only  160  pounds  of  total  phosphorus  and  1000  pounds  of  total 
calcium;  that  is,  sufficient  total  phosphorus  and  total  calcium 
in  the  plowed  soil  of  an  acre  for  about  8  crops  of  clover,  with  such 
yields  as  we  can  and  do  produce  on  our  best-treated  land  in  good 
seasons  (4  tons  in  2  cuttings),  —  until  these  impoverished  lands 
surrounding  the  National  Capital  have  been  rehabilitated  and 
changed  in  value  from  $1.50  to  $150  an  acre,  by  crop  rotation,  or 
even  by  live-stock  farming  without  the  purchase  of  plant  food  in 
feed  or  fertilizers,  —  until  these  results  have  actually  been  accom- 
plished, the  student  of  agriculture  is  earnestly  warned  against 
accepting  any  predictions  that  the  farmers  of  Kansas  or  of  any 
other  states  are  actually  enriching  their  soils  because  they  are 
practicing  live-stock  farming  to  a  greater  or  less  extent.  The 
student  is  urged  to  have  faith  in  the  exact  data  of  scientific  inves- 
tigations, such,  for  example,  as  those  conducted  for  more  than  60 
years  at  Rothamsted,  England,  and  for  about  30  years  at  Urbana, 
Illinois,  and  at  State  College,  Pennsylvania,  full  records  of  which 
are  given  in  the  following  pages. 

Of  course  the  small  commercial  countries  of  Europe  which  retain 
practically  all  of  their  own  fertility  and  import  much  more  in 
food  stuffs  and  fertilizers  can  markedly  enrich  their  soils,  just  as 
some  of  our  small  states  can  build  up  some  small  areas  of  culti- 
vated lands;  but  as  the  average  yield  of  corn  in  the  great  state 
of  Georgia  is  only  n  bushels  per  acre,  so  the  average  yield  of  wheat 
on  the  "  black  soils  "  of  Russia,  for  the  20  years,  1883  to  1902,  is' 
8^  bushels  per  acre,  and  as  a  rule  this  land  lies  fallow  every  third 
year.  The  following  comment  is  recorded  on  page  27  of  Bulletin  42 


THEORIES    CONCERNING   SOIL   FERTILITY       333 

of  the  Bureau  of  Statistics,  United  States  Department  of  Agri- 
culture: 

"It  may  be  claimed  that  this  extremely  low  average  yield  in  European  Russia 
is  caused  by  the  total  failure  of  crops  in  famine  years,  and  that  these  should 
have  been  omitted  in  calculating  the  average  for  a  series  of  years.  But  the 
extreme  variability  of  the  average  yield  is  no  less  a  characteristic  feature  of  Rus- 
sian agriculture  than  its  very  low  yield;  and  the  famine  years  have  been  so 
frequent  as  to  become  a  permanent  feature  of  Russian  agriculture,  each  one  of 
the  five-year  periods  including  at  least  one  famine  year,  and  some  even  two." 

It  may  be  added  that  in  famine  years  the  average  yield  of  wheat 
in  Russia  is  6^  bushels,  the  lowest  recorded  average  yield  being 
5^  bushels  per  acre. 

In  India  the  average  yield  of  cotton  on  the  "  black  cotton  soils  " 
is  less  than  100  pounds  of  lint  per  acre.  The  following  extract  from 
an  article  written  by  Saint  Nihal  Singh  of  India  (see  Wallaces' 
Farmer,  April  30,  1909)  is  given  as  a  faithful  description  of  the 
present  condition  of  our  cousins  in  India,  the  Eastern  Branch  of 
our  own  Aryan1  race,  "  the  sons  of  Japheth  ": 

"If  the  American  farmer  were  to  seek  contrast  to  his  life  and  labor,  he 
would  find  it  on  the  farm  in  India ;  and  the  contrast  would  be  as  clearly  defined 
as  that  which  exists  between  day  and  night." 

"Almost  all  the  farm  land  has  to  be  irrigated.  While  the  rainfall  is  heavy  at 
seasons,  it  is  uncertain,  and  prolonged  drouths  make  irrigation  positively  neces- 
sary." (In  the  main  the  water  for  irrigation  is  collected  in  ponds  or  large  shal- 
low wells  during  the  rainy  season,  and  then  drawn  to  the  fields  by  oxen  or  carried 
by  hand  as  needed.  When  the  monsoons  fail  and  the  wells  or  reservoirs  are  not 
filled,  at  least  partial  crop  failure  results,  and  famine  is  likely  to  follow.  — 
C.  G.  H.) 

"  The  farm  in  India  is  very  small  in  area.  It  is  very  rarely  larger  than  ten 
or  twenty  acres  —  often  it  is  only  two  or  three  acres. 

1  "  The  languages  of  all  these  branches  or  groups  of  people  are  akin ;  that  is  to 
say,  they  are  descendant  of  one  original  tongue,  once  spoken  in  a  limited  locality, 
by  a  single  community,  but  where  or  when  it  is  impossible  to  say. 

"Many  words  still  live  in  India  and  England  that  have  witnessed  the  first 
separation  of  the  northern  and  southern  Aryans,  and  these  are  witnesses  not  to  be 
shaken  by  any  cross  examination.  The  terms  for  God,  for  house,  for  father,  mother, 
son,  daughter,  for  dog  and  cow,  for  heart  and  tears,  for  axe  and  tree,  identical  in 
all  the  Indo-European  idioms,  are  like  the  watchwords  of  soldiers.  We  challenge 
the  seeming  stranger;  and  whether  he  answer  with  the  lips  of  a  Greek,  a  Ger- 
man, or  an  Indian,  we  recognize  him  as  one  of  ourselves.  There  was  a  time  when 
the  ancestors  of  the  Celts,  the  Germans,  the  Slavonians,  the  Greeks  and  Italians, 
the  Persians  and  Hindus,  were  living  together  beneath  the  same  roof,  separate  from 
the  ancestors  of  the  Semitic  and  Turanian  races. "  —  MAX  MULLER. 


334 


SYSTEMS    OF   PERMANENT   AGRICULTURE 


"As  to  the  nature  of  the  crops  grown  in  the  country:  wheat,  corn,  various 
kinds  of  peas  and  lentils,  cotton,  and  sugar  cane  are  grown  exclusively  in  north- 
ern India,  except  such  portions  where  the  lands  are  low  and  the  rainfall  heavy 
where  rice  is  grown.  Rice  is  the  principal  crop  in  southern  India." 

"Considering  the  amount  of  hard  drudging  work  that  the  Indian  farmer  puts 
into  his  work,  the  yield  l  from  the  labor  is  pitifully  disappointing." 

"At  harvest  time  extra  hands  are  needed  and  they  are  employed  by  the  far- 
mer, who  agrees  to  pay  them  a  certain  amount  of  grain  to  compensate  them  for 
their  labor.  If  payment  is  made  in  coin,  it  seldom  exceeds  two  and  a  half  annas 
(five  cents 2)  a  day.  The  income  of  the  average  East  Indian,  according  to  gov- 
ernmental statistics,  is  only  fifty  cents  a  month,  and  farmers,  as  a  community, 
live  in  the  most  miserable  poverty. 

"There  are  450,000  square  miles  of  waste  land  in  Hindustan,  or  nearly  one 
fourth  of  the  country,  that  is  to-day  uncultivated,  though  capable  of  yielding 
rich  harvests.  The  people  of  India  do  not  know  enough  to  bring  these  lands 
under  cultivation.  The  soil  that  is  in  use  is  never  allowed  to  lie  fallow,  even 
for  a  brief  space  of  time.  Crops  follow  one  another  in  quick  rotation.  The 
farmer  lacks  the  knowledge  and  resources  to  enrich  his  land  by  means  of  fer- 
tilizers. The  only  fertilizer  that  he  knows  about  is  cow  dung  and,  unfor- 

1  Nitya  Gopal  Mukerji,  Professor  of  Agriculture  and  Agricultural  Chemistry  in 
the  Civil  Engineering  College  at  Sibpur,  Bengal,  India,  in  his  "Handbook of  Indian 
Agriculture"  (1907),  reports  "the  area  under  food  grains  in  India  at  164  million 
acres  and  the  produce  of  grain  per  acre  per  annum  at  840  lb.,  and  the  population 
at  350  millions." 

There  are  about  70  million  acres  of  rice  and  nearly  30  million  acres  of  wheat. 
The  average  yields  are  estimated  at  17  bushels  of  rice  (of  60  lb.  each),  about  10 
bushels  of  wheat,  and  7  to  12  bushels  of  corn,  per  acre,  and  in  the  main  the  crops 
are  grown  under  irrigation. 

The  following  quotations  from  Mukerji  are  of  interest: 

"The  farmer  aims  at  doing  without  manures  (the  English  term  for  commercial 
fertilizers)  as  much  as  possible,  at  keeping  up  the  fertility  of  his  land  simply  by 
feeding  his  cattle  with  nourishing  oil  cakes  and  utilizing  all  the  cattle  dung,  urine, 
and  litter  in  manuring  his  fields.  By  growing  leguminous  crops  and  by  adopting 
a  judicious  system  of  rotation  he  also  tries  to  avoid  the  purchase  of  manures  (fer- 
tilizers)." 

"  The  reported  fertility  of  Indian_  soils  is  more  a  myth  than  a  reality.  Where 
the  soil  has  been  in  cultivation  for  many  years,  the  virgin  richness  has  disappeared, 
except  where  it  is  irrigated  by  canals  (e.g.,  the  Eden  Canal)  bringing  rich  desposits  of 
silt,  or  annually  flooded  by  rivers  leaving  such  deposits  (e.g.,  in  eastern  Bengal). 
As  a  rule,  Indian  soils  yield  poor  crops. 

"In  the  famine  of  1770,  in  nine  months,  ten  million  people  died  in  Bengal. 
The  famine  of  1784  was  of  such  a  bad  type  that  four  seers  (8  lb.)  of  wheat  were  sold 
for  a  rupe  (48  ct.),  and  the  deaths  from  starvation  were  innumerable.  The  most 
recent  of  all  famines,  viz.,  that  prevailing  in  some  part  of  India  or  other  from  1897 
to  1900,  has  been  severer  than  the  famine  of  1874-1878." 

*  The  anna  is  about  3  cents,  but  it  sometimes  depreciates  to  less  than  2  cents. 
—  C.  G.  H. 


THEORIES    CONCERNING   SOIL   FERTILITY        335 

tunately,  he  is  able  to  spare  little  of  this  for  enriching  the  field,  for  timber 
is  scarce  in  most  parts  of  India  and  the  cow  chips  are  used  for  fuel. 

"When  these  old-fashioned  methods  are  taken  into  consideration,  it  is  easy 
to  understand  why  agriculture  does  not  pay  in  India.  Since  95  per  cent  of  the 
people  of  Hindustan  are  engaged  in  farming  or  allied  industries,  it  is  easy  to 
realize  why  the  people  of  India  live  in  excruciating  poverty.  Famine  rages  in 
the  country  all  the  year  round,  and  it  will  continue  to  do  so  until  the  East 
Indian  agriculturist  is  taught  to  use  better  methods.  As  it  is,  only  one  out  of 
147  women  and  only  ten  out  of  100  men  farmers  are  capable  of  reading  and 
writing,  and  only  one  out  of  every  five  villages  in  India  has  a  schoolhouse. 

"The  home  life  of  the  farmer  is  so  filled  with  desperate  poverty  that  it  lacks 
all  picturesque  details.  .  .  .  The  house  usually  consists  of  but  one  room  or,  at 
best,  two  or  three,  and  all  of  these  are  most  rudely  furnished.  There  are  no 
carpets  on  the  floor,  which  is  of  dirt,  uncovered  by  boards  or  even  by  matting. 
The  men  and  women  usually  squat  on  the  floor,  using  small,  narrow  pieces  of 
gunny  sacks  to  sit  on.  The  bedstead  is  home-made  and  may  be  described  as  a 
cot  made  in  the  most  elementary  manner  of  bamboo  laced  across  with  coarse 
twine.  The  same  room  is  used  for  storing  goods  of  all  descriptions,  preparing 
and  eating  food,  and  for  sitting  and  sleeping  purposes.  Not  unoften  the  cattle 
are  given  a  corner  in  the  room.  Since  the  married  sons  of  the  father  live  at 
home,  the  shortage  of  space  compels  two  or  three  families  to  herd  together  in 
the  same  apartment. 

"Life  for  the  woman  is  especially  filled  with  drudgery.  She  gets  up  between 
three  and  four  o'clock  in  the  morning.  While  the  husband  is  feeding  the  stock 
she  milks  the  cows.  Over  night  the  milk  has  been  boiled  and  allowed  to  curdle. 
The  woman  puts  it  into  an  earthen  pot  and  churns  it.  Buttermilk  forms  an 
important  item  of  the  scanty  breakfast.  About  the  only  thing  that  the  farmer 
eats  along  with  the  whey  is  corn  or  wheat  bread,  which,  unlike  in  this  country, 
is  made  thin  like  a  pancake  and  six  or  eight  inches  in  diameter.  Both  men  and 
women  take  a  bite  of  this  bread  and  pour  down  a  quantity  of  buttermilk.  In 
eating  no  knives,  forks,  spoons,  are  employed.  The  fingers  are  made  to  perform 
the  various  eating  operations." 

"The  life  of  great  hardship  and  excruciating  poverty  that  farmers  in  India 
are  obliged  to  lead  makes  them  subnormal.  They  lack  vim  and  vitality.  In 
their  waking  moments  they  are  only  half  awake.  Through  insufficient  nutrition 
they  are  unable  to  do  the  hard  physical  work  they  would  be  able  to  do  otherwise. 
Naturally  the  people  in  India  are  fatalists  by  religion.  They  look  upon  life 
as  an  adversity  that  has  to  be  shouldered  as  best  it  can  be.  They  are  not  afraid 
of  death;  in  fact,  they  long  for  death,  for  they  believe  that  on  the  other  side  of 
existence  they  would  lead  a  happier  and  a  better-fed  life.  Thus  do  the  people  of 
India  live  and  labor." 

In  China,  the  fourth  great  agricultural  country  comparable  with 
the  United  States  in  extent  and  necessary  self-dependence,  there 
are  areas  of  arable  upland  plains,  sometimes  100  square  miles  or 


336 

more  in  extent,  that  are  not  now  populated,  the  reclamation  of 
which  has  been  called  the  "  Problem  of  China." 

The  information  available  is  not  sufficient  to  determine  to  what 
extent  the  waste  lands  of  India  and  China  represent  abandoned 
farms  that  were  once  cultivated,  but  it  is  fully  known  that  to  some 
extent  this  is  the  case.  On  the  other  hand,  the  Chinese  have  main- 
tained well  the  fertility  of  much  of  the  lands  they  are  now  culti- 
vating. The  explanation  is  found  in  the  following  quotations,  taken 
largely  from  Sir  Humphry  Davy's  "Agricultural  Chemistry"  (1827) 
and  from  Davis,  Fortune,  and  other  writers,  through  extracts 
published  in  the  works  of  Baron  Justus  von  Liebig  (1840  to  1859) : 

"The  Chinese,  who  have  more  practical  knowledge  of  the  use  and  application 
of  manures  than  any  other  people  existing,  mix  their  night  soil  with  one  third 
of  its  weight  of  a  fat  marl,  make  it  into  cakes,  and  dry  it  by  exposure  to  the  sun. 
These  cakes,  we  are  informed  by  the  French  missionaries,  have  no  disagreeable 
smell,  and  form  a  common  article  of  commerce  of  the  empire."  —  DAVY. 

"Davis,  in  his 'History  of  China,' states  that  every  substance  convertible  into 
manure  is  diligently  husbanded.  'The  cakes  that  remain  after  the  expression 
of  their  vegetable  oils,  horns,  and  hoofs  reduced  to  powder,  together  with  soot 
and  ashes,  and  the  contents  of  common  sewers  are  much  used.  The 
plaster  of  old  kitchens,  which  in  China  have  no  chimneys,  but  an  opening 
at  the  top,  is  much  valued  :  so  that  they  will  sometimes  put  new  plaster  on 
a  kitchen  for  the  sake  of  the  old.  All  sorts  of  hair  are  used  as  manure,  and 
barber's  shavings  are  carefully  appropriated  to  that  purpose.  The  annual 
produce  must  be  considerable,  in  a  country  where  some  hundred  millions  of 
heads  are  kept  constantly  shaved.  Dung  of  all  animals,  but  more  especially 
night  soil,  is  esteemed  above  all  others.  Being  sometimes  formed  into  cakes, 
it  is  dried  in  the  sun,  and  in  this  state  becomes  an  object  of  sale"  to  farmers, 
who  dilute  it  previous  to  use.  They  construct  large  cisterns  or  pits  lined 
with  lime  plaster,  as  well  as  earthen  tubs  sunk  in  the  ground,  with  straw 
over  them  to  prevent  evaporation,  in  which  all  kinds  of  vegetable  and  animal 
refuse  are  collected.  These,  being  diluted  with  a  sufficient  quantity  of  liquid, 
are  left  to  undergo  the  putrefactive  fermentation,  and  then  applied  to  the  land." 

"  Human  urine  is,  if  possible,  more  husbanded  by  the  Chinese  than  night  soil 
for  manure;  every  farm,  or  patch  of  land  for  cultivation,  has  a  tank  where  all 
substances  convertible  into  manure  are  carefully  deposited,  the  whole  made 
liquid  by  adding  urine  in  the  proportion  required,  and  invariably  applied  to 
the  soil  in  that  state.  The  business  of  collecting  urine  and  night  soil  employs 
an  immense  number  of  persons,  who  deposit  tubs  in  every  house  in  the  cities 
for  the  reception  of  the  urine  of  the  inmates,  which  vessels  are  removed  daily 
with  as  much  care  as  our  farmers  remove  their  honey  from  the  hives.  The 
night  soil  is  collected  in  the  same  way,  as  well  as  on  the  roads  and  by-places, 


THEORIES    CONCERNING   SOIL   FERTILITY       337 

persons  being  always  on  the  alert  with  baskets  and  rakes  to  avail  of  the  least 
particle  that  appears.  The  Chinese  get  as  much  off  their  land  as  it  is  capable 
of  producing,  and  this  is  done  by  the  liberal  use  of  manure  and  application  of 
much  more  labor  in  working  the  soil  than  in  other  countries.  The  reason  they 
do  not  use  dung  is  that  they  have  comparatively  no  animals." 

"It  is  quite  impossible  for  us  in  Europe  to  form  an  adequate  conception  of 
the  great  care  which  is  bestowed  in  China  upon  the  collection  of  human  excre- 
ments. In  the  eyes  of  the  Chinese,  these  constitute  the  true  sustenance  of  the 
soil  (so  Davis,  Fortune,  Hedde,  and  others  tell  us),  and  it  is  principally  to  this 
most  energetic  agent  that  they  ascribe  the  activity  and  fertility  of  the  earth." 

"Except  the  trade  in  grain,  and  in  articles  of  food,  generally  there  is  none  so 
extensively  carried  on  in  China  as  that  in  human  excrements.  Long,  clumsy 
boats,  which  traverse  the  street  canals,  collect  these  matters  every  day,  and  dis- 
tribute them  over  the  country.  Every  coolie  who  has  brought  his  produce  to 
market  in  the  morning  carries  home  at  night  two  pails  full  of  this  manure  on  a 
bamboo  pole. 

I11  The  estimation  in  which  it  is  held  is  so  great  that  everybody  knows  the 
amount  of  excrements  voided  per  man  in  a  day,  month,  or  year ;  and  a  Chinese 
would  regard  as  a  gross  breach  of  manners  the  departure  from  his  house  of  a 
guest  who  neglects  to  let  him  have  that  advantage  to  which  he  deems  himself 
justly  entitled  in  return  for  his  hospitality.  The  value  of  the  excrements  of  five 
people  is  estimated  at  two  Teu  per  day,  which  makes  2000  Cash l  per  annum, 
or  about  twenty  hectoliters  (440  gals.),  at  a  price  of  seven  florins."  w 

"Every  substance  derived  from  plants  and  animals  is  carefully  collected  by 
the  Chinese  and  converted  into  manure.  Oil  cakes,  horn,  and  bones  are 
highly  valued,  and  so  is  soot,  and  especially  ash.  To  give  some  notion  of  the 
value  set  by  them  upon  animal  offal  it  will  be  sufficient  to  mention  that  the 
barbers  most  carefully  collect,  and  sell  as  an  article  of  trade,  the  somewhat  con- 
siderable amount  of  hair  of  the  beards  and  heads  of  the  hundreds  of  millions 
of  customers  whom  they  daily  shave.  The  Chinese  know  the  action  of  gypsum 
and  lime;  and  it  often  happens  that  they  renew  the  plastering  of  the  kitchens 
for  the  purpose  of  making  use  of  the  old  matter  for  manure." —  DAVIS. 

"During  the  summer  months  all  kinds  of  vegetable  refuse  are  mixed  with 
turf,  straw,  peat,  weeds,  and  earth,  collected  into  heaps,  and  when  quite  dry, 
set  on  fire ;  after  several  days  of  slow  combustion  the  entire  mass  is  converted 
into  a  kind  of  black  earth.  This  compost  is  only  employed  for  the  manuring  of 
seeds.  When  seedtime  arrives,  one  man  makes  holes  in  the  ground;  another 
follows  with  the  seed,  which  he  places  in  the  holes ;  and  a  third  adds  this  black 
earth.  The  young  seed  planted  in  this  manner  grows  with  such  extraordinary 
vigor  that  it  is  thereby  enabled  to  push  its  rootlets  through  the  hard  solid  soil, 
and  to  collect  its  mineral  constituents."  —  FORTUNE. 

"The  Chinese  farmer  sows  his  wheat,  after  the  grains  have  been  soaked  in 

1  The  Chinese  coin  tsien  (pronounced  chen),  called  cash  by  foreigners,  is  valued 
at  about  one  tenth  of  a  cent.  —  C.  G.  H. 


338       SYSTEMS    OF   PERMANENT  AGRICULTURE 

liquid  manure,  quite  close  in  seed  beds  and  afterwards  transplants  it.  Oc- 
casionally, also,  the  soaked  grains  are  immediately  sown  in  the  field  properly 
prepared  for  their  reception,  at  an  interval  of  four  inches  from  each  other.  The 
time  of  transplanting  is  toward  the  month  of  December.  In  March  the  seed 
send  up  from  seven  to  nine  stalks  with  ears,  but  the  straw  is  shorter  than  with 
us.  I  have  been  told  that  wheat  yields  120  fold  and  more,  which  amply  repays 
the  care  and  labor  bestowed  upon  it." 

—  ECKEGERG,  in  Report  to  the  Academy  of  Sciences  at  Stockholm,  1765. 

"In  Chusan,  and  the  entire  rice  districts  of  Chekiang,  and  Keangaoo,  two 
plants  are  exclusively  cultivated  for  the  purpose  of  serving  as  green  manure  for 
the  rice  fields;  the  one  is  a  species  of  Coronilla,  clover  is  the  other.  Broad  fur- 
rows, similar  to  those  intended  for  celery,  are  made,  and  the  seeds  are  planted 
on  the  ridges  in  patches,  at  a  distance  of  five  inches  from  each  other.  In  the 
course  of  a  few  days  germination  begins,  and  long  before  the  winter  is  gone  the 
entire  field  is  covered  with  a  luxuriant  vegetation.  In  April  the  plants  are 
plowed  in ;  and  decomposition  soon  begins,  attended  with  a  most  disagreeable 
odor.  This  method  is  adopted  in  all  places  where  rice  is  grown." — FORTUNE. 

^.^ 

"These  extracts,"  said  Liebig,  "which,  from  want  of  space, 
cannot  be  further  extended,  will  probably  suffice  to  convince  the 
German  agriculturist  that  his  practice,  when  compared  with  that 
of  the  oldest  agricultural  nation  in  the  world,  stands  somewhat  in 
the  position  of  the  acts  of  a  child  to  those  of  a  full-grown  and 
experienced  man." 

A  communication  dated  Chengtu,  Szechuan,  China,  July  4,  1907, 
from  Elrick  Williams  (formerly  associated  with  the  author,  as 
student  and  teacher,  at  the  University  of  Illinois)  contains  the 
following  information: 

"One  of  the  first  things  which  attract  the  attention  of  a  foreigner  on  reach- 
ing China  is  the  simple  form  of  closets  and  'outhouses'  in  vogue.  Private  ones 
consist  of  a  square  box  in  which  is  placed  an  earthenware  vessel  usually  smaller 
than  a  bushel  basket.  A  stranger  will  notice  that  it  is  empty  every  morning, 
even  at  an  early  hour.  Greater  still  is  one's  astonishment  to  note  along  the 
streets  convenient  places  for  accommodating  one's  necessity  in  this  regard.  They 
are,  of  course,  very  simple.  Along  the  river  where  there  are  multitudes  of 
trackers  (men  who  tow  the  boats),  one  finds  earthenware  vessels  set  in  the 
ground  behind  a  half  circle  of  matting  about  three  or  four  feet  high.  Enter- 
prising farmers  put  these  in  to  reap  the  passing  reward.  Last,  but  by  no  means 
least,  is  the  man  with  the  dung  basket  and  fork.  The  man  may  be  a  woman 
or  child  but  the  majority  are  grown  men.  They  haunt  the  streets,  alleys,  lanes, 
or  loafing  places  of  men,  and  the  feeding  places  of  beasts.  I  have  seen  a 
woman  run  down  a  steep  hill  with  a  basket  in  order  to  be  nearest  to  a  squatting 
tracker.  Before  he  is  twenty  feet  away,  often  the  prize  is  gathered  up. 


339 

"Human  manure  is  the  most  highly  prized,  although  a  friend  told  me  that 
the  manure  from  silk  worms  was  even  more  valuable.  Dog  manure,  pig 
manure,  cow  manure,  and  water  buffalo  manure  are  prized  in  about  this  order." 

Thus  do  the  people  of  China  follow  the  products  of  the  land  to 
the  place  of  consumption  and  return  to  the  soil  every  possible 
recoverable  residue,  and  to  this  are  added  a  large  use  of  legume 
crops  and  applications  of  muck,  marl,  lime,  etc.,  and  silt  deposits 
on  overflowed  or  irrigated  lands.  (See  also  page  594.) 

The  following  quotations  from  circular  letters  from  Doctor  Al- 
fred M.  Peter,  Head  of  the  Division  of  Agricultural  Chemistry  of 
the  Kentucky  University  Agricultural  Experiment  Station,  will 
be  of  interest  to  the  student  (see  also  pages  263-267,  Vol.  i, 
Journal  of  Industrial  and  Engineering  Chemistry,  April,  1 909) : 

"LEXINGTON,  KY.,  January  21,  1909. 

"DEAR  SIR: 

"  In  a  '  Hearing  before  the  Committee  on  Agriculture  of  the  House  of  Repre- 
sentatives,' 1908,  Doctors  Whitney  and  Cameron  of  the  Bureau  of  Soils  have 
made  statements  to  the  effect  that  the  recent  teachings  of  the  Bureau  in  regard 
to  soil  fertility  are  generally  accepted  throughout  this  country  and  Europe,  and 
that  they  are  being  widely  taught  in  the  Agricultural  Colleges  of  this  country. 
The  teachings  referred  to,  with  which  you  are,  no  doubt,  familiar,  may  be  sum- 
marized in  the  following  statements: 

"  i.  That  all  soils  contain  enough  mineral  plant  food  in  available  form  for 
maximum  crops,  and  that  this  supply  will  be  indefinitely  maintained. 

"  2.  That  the  real  cause  of  infertility  is  the  accumulation  in  the  soil  of  poison- 
ous excreta  from  plant  roots. 

"  3.  That  it  is  not  ever  necessary  to  add  fertilizers  for  the  purpose  of  increas- 
ing the  plant  food  in  the  soil,  the  good  effect  of  fertilizers  being  due  to  their 
power-of  neutralizing  or  destroying  these  toxic  substances  or  their  activity. 

"  4.  That  soil  fertility  can  be  maintained  indefinitely  by  practicing  a  system 
of  rotation  by  which  a  crop  is  grown  each  year  that  is  not  injured  by  the  ex- 
creta of  the  preceding  crop. 

"  In  order  to  ascertain  just  how  extensively  these  views  are  accepted  and  taught 
in  our  Agricultural  Colleges  and  Experiment  Stations,  the  writer  is  sending 
this  letter  to  professors  of  agriculture,  agronomists,  and  agricultural  chemists  in 
all  such  institutions  on  the  "Organization  Lists."  It  is  proposed  to  publish  a 
summary  of  the  data  obtained,  without  giving  names  of  institutions  or  individ- 
uals. Will  you  kindly  assist  by  telling  me  whether  or  not  these  views  are  ac- 
cepted and  taught  by  you  or  your  institution,  or  by  referring  this  letter  to  some 
one  who  will  give  me  an  authoritative  answer  ? 

"  Yours  very  truly, 
(Signed)  "ALFRED  M.  PETER." 


SYSTEMS    OF   PERMANENT  AGRICULTURE 

"  LEXINGTON,  KY.,  February  18,  1909. 

"DEAR  SIR: 

"  Replies  to  my  letter  of  January  21  have  now  been  received  from  104  in- 
dividuals in  the  United  States  and  Canada,  including  35  Agricultural  Chemists, 
25  Agronomists,  21  Professors  of  Agriculture,  9  Soil  Specialists,  both  chemists 
and  physicists,  8  Experiment  Station  Directors,  not  otherwise  classified,  3 
Directors  of  Farmers'  Institutes,  i  Professor  of  Vegetable  Pathology,  i  of  Hor- 
ticulture, and  i  of  Natural  Science.  Out  of  these  only  two  indorse  the  Bureau's 
views  without  qualification  and  say  they  are  taught  in  their  institutions  as  estab- 
lished facts.  These  two  are  from  minor  or  branch  institutions,  however,  not 
one  of  the  Land-grant  Colleges  or  State  Experiment  Stations  being  willing  to 
accept  or  teach  them  in  the  sense  in  which  they  have  been  put  forward  by  the 
Bureau.  About  half  recognize  more  or  less  truth  in  the  doctrines,  and  present 
and  discuss  them  in  advanced  teaching.  Most  of  them  recognize  the  value  of 
the  Bureau's  work  on  toxic  substances  and  consider  them  a  possible  factor  in 
soil  fertility,  though  not  the  most  important  one.  The  rest  either  say  they  do 
not  accept  and  teach  the  Bureau's  views  on  these  subjects,  or  oppose  them. 
The  Agricultural  Colleges  and  Experiment  Stations  in  47  States  and  Terri- 
tories of  the  United  States  are  represented  in  these  answers,  showing  a  very 
general  interest  in  the  subject  of  the  inquiry.  It  is  apparent  that  while  the 
Bureau's  views  on  soil  fertility  are  not  being  accepted  and  taught  as  established, 
in  these  institutions,  they  are  being  generally  presented  and  discussed  in  ad- 
vanced teaching  of  agriculture. 

"  In  a  letter  to  me  dated  January  28,  a  copy  of  which  has  been  sent  to  you, 
Doctor  Cameron  takes  exception  to  my  presentation  of  the  Bureau's  teachings 
and  explains  his  position  in  this  matter.  Doctor  Whitney  in  a  letter  to  me  ap- 
proves Doctor  Cameron's  letter,  so  it  may  be  taken  as  an  authoritative  ex- 
pression of  the  Bureau's  views.  If,  after  reading  it,  you  desire  to  modify  your 
opinion  already  expressed  to  me,  I  will  be  glad  to  hear  from  you  before  making 

my  final  publication.  « ,r  , 

"  Yours  very  truly, 

(Signed)  "ALFRED  M.  PETER." 

From  the  numerous  exact  quotations  hereinbefore  given  the 
student  will  be  able  to  determine  for  himself  how  fairly  Doctor 
Peter  has  summarized  the  teachings  of  the  Bureau  of  Soils.  Under 
date  of  July  3,  1909,  Doctor  Peter  wrote  the  author  as  follows: 

"  About  half  of  my  correspondents  wrote  me  again  to  say  that  Doctor 
Cameron's  letter  had  made  no  change  in  their  views.  I  did  not  hear  from 
any  one  who  desired  to  change  his  expression  of  opinion." 

The  persistent  and  long-continued  teaching  of  the  Federal 
Bureau  of  Soils,  that  the  fertility  of  the  soil  can  be  indefinitely 
maintained  without  the  restoration  of  plant  food,  is  widely  pro- 
mulgated by  inspired  press  reporters  and  other  prolific  writers  and 


THEORIES   CONCERNING   SOIL   FERTILITY       341 

gladly  accepted  by  land  agents  and  by  landowners  inexperienced 
in  the  management  of  truly  depleted  soils. 

And  why  not  ?  No  doctrine  could  be  more  pleasing,  —  an  in- 
exhaustible national  asset !  —  a  self-maintaining  food  supply  !  —  a 
dish  from  which  we  can  eat  and  eat,  to-day,  to-morrow,  and  for- 
ever !  —  a  bank  account  which  requires  for  its  maintenance  only 
the  rotation  of  the  check  book  among  the  members  of  the  family ! 
—  a  "  philosopher's  stone  "  that  creates  an  infinite  supply  of  golden 
grain  from  finite  quantities  of  baser  materials  ! 

The  possible  enormous  and  irreparable  damage  of  such  teach- 
ing lies  in  the  fact  that  even  our  remaining  supply  of  good  land 
will  ultimately  be  depleted  by  the  present  practices  beyond  the 
point  of  self-redemption,  thus  repeating  the  history  of  our  aban- 
doned Eastern  lands,  where  the  rotation  of  crops  was  the  com- 
mon rule  of  practice  for  more  than  a  hundred  years. 

The  following  extracts  are  typical : 

"  SOILS  NOT  WEARING  OUT 

"  A  most  comprehensive  bulletin  has  recently  been  published  by  the  Na- 
tional Department  of  Agriculture  dealing  with  the  question  of  soil  composition." 

"  The  facts  and  figures  presented  in  this  bulletin  tend  to  show  that  there 
is  not  any  immediate  danger  of  the  soils  of  the  United  States  wearing  out. " 

"Considering  the  fact  that  the  farms  of  the  United  Kingdom  have  been 
under  cultivation  for  a  thousand  years  or  more,  it  is  held  by  Professor  Whitney 
that  continuous  cropping  does  not  necessarily  tend  to  decrease  production." 

"  We  believe  that  Professor  Whitney's  statements  will  come  as  a  surprise 
to  a  great  majority  of  our  readers,  because  the  average  man  labors  under  the 
belief  that  soils  are  gradually  wearing  out ;  on  the  other  hand,  it  is  a  fact  that 
our  leading  farmers,  in  every  state  in  the  Union,  are  not  only  able  to  main- 
tain their  crop  yield,  but  they  are  increasing  it  from  year  to  year." 

"  It  is  true  that  there  may  be  annually  some  loss.of  mineral  elements,  but  in 
ordinary  good  soils,  such  as  our  clays  and  loams,  the  supply  of  these  minerals 
is  so  great  that  a  five-hundred  or  even  a  thousand-year  period  will  not  reduce 
the  supply  to  a  point  where  production  is  materially  affected."  —  The  Home- 
stead, October  28,  1909. 

"  FERTILITY  OF  SOIL 

"  Artificial  Fertilizers  Said  to  be  all  Wrong 
"  Special  Correspondence. 

"WASHINGTON,  Nov.  17.  —  Artificial  fertilizers  —  phosphates  and  nitrates, 
chiefly — act  upon  the  soil  as  drugs  act  upon  the  human  body,  according  to 


342        SYSTEMS    OF   PERMANENT   AGRICULTURE 

investigations  just  completed  by  the  Bureau  of  Soils  of  the  Department  of 
Agriculture. 

"  Although  there  are  some  experiments  and  some  tabulation  of  results  yet 
to  be  made,  the  scientists  have  gone  far  enough  to  evolve  a  theory  that  may 
upset  present-day  methods  of  agriculture. 

"  The  new  theory  is  based  on  a  series  of  experiments  that  have  been  con- 
ducted during  the  summer  and  for  several  years  prior  to  this  season.  They 
intend  to  show  that  there  are  natural  agencies  at  work  in  the  soil  that  will 
replenish  worn-out  'soil  tissues'  just  as  the  worn-out  tissues  of  the  body  in 
man  are  replaced  by  agencies  inside.  Only  in  the  case  of  man  there  is 
usually  a  limit  to  this  process,  whereas,  in  soils,  the  scientists  have  observed 
some  wonderful  results  from  soils  long  ago  abandoned  as  useless. 

"  Sensible  rotation  of  crops  will  produce  much  better  and  more  lasting 
results  than  the  artificial  fertilization  of  soils,  say  the  experts"  —  Freeport 
(Illinois)  Daily  Buttetin,  November  19,  1909. 

"  SECRETARY  WILSON  ON  EASTERN  FARMING 

"  Secretary  of  Agriculture  Wilson  has  been  traveling  through  some  of  the 
Eastern  States  for  the  purpose  of  studying  farming  conditions,  and  is  quoted 
as  saying: 

' '  It  was  a  beautiful  country  that  we  passed  through,  but  the  farms  gener- 
ally did  not  show  prosperity.  Many  of  the  districts  looked  depopulated.  We 
saw  plenty  of  children  in  the  villages,  but  few  in  the  rural  regions.  The  coun- 
try looked  deserted.  In  fact,  interest  in  agriculture  appears  to  have  declined.' 
'  The  soils  in  this  state  are  not  exhausted.  In  some  cases  they  have  be- 
come unproductive  by  failure  to  rotate  crops,  and  again  because  there  has 
been  no  change  of  seed.  I  am  told  that  many  farmers  hereabout  have  planted 
seed  from  the  same  source  for  fifty  years.  In  the  West  they  know  the  value 
of  changing  seed.  We  have  searched  the  world  for  seeds  which  would  flour- 
ish in  all  climates  and  conditions,  and  we  are  going  to  increase  our  production 
by  making  use  of  them.' "  —  Wallaces1  Farmer,  November  5,  1909. 

In  conclusion  it  may  be  stated  that  the  four  great  fundamental 
facts  of  plant  nutrition  still  stand  against  every  test:  thus,  Sen6- 
bier's  proof  of  the  fixation  of  carbon,  oxygen,  and  hydrogen  by 
photosynthesis,  De  Saussure's  discovery  of  the  presence  and  abso- 
lute necessity  of  mineral  plant  food,  Lawes  and  Gilbert's  proof 
that  the  soil  must  furnish  the  nitrogen  for  most  plants,  and  Hell- 
riegel's  discovery  of  the  fixation  of  free  nitrogen  by  the  bacteria 
of  legumes  always  lead  to  the  same  conclusion  whenever,  wherever, 
or  by  whomsoever  they  are  repeated.  They  are  fully  recognized 
as  absolutely  established  facts,  at  least  as  well  established  as  the 
fact  that  the  earth  is  round. 


SIR  JOHN  BENNET  LAWES  (1814-1900) 


PART    III 

SOIL   INVESTIGATION    BY   CULTURE 
EXPERIMENTS 

IN  the  preceding  pages  we  have  considered  the  subject  of  soil 
fertility  in  large  part  from  the  chemical  and  mathematical  stand- 
point (the  last  chapter  being  disregarded).  Thus,  we  have  dis- 
cussed briefly  the  chemical  composition  of  earth,  air,  water,  plants, 
and  animals;  the  essential  plant-food  elements  and  their  relative 
abundance  in  plants  and  in  plant  and  animal  products  and  resi- 
dues, also  in  normal  and  abnormal  soils;  and  the  sources  and  forms 
of  materials  whose  use  is  necessary  for  the  adoption  of  systems  of 
permanent  agriculture  on  ordinary  lands  under  general  farming. 

We  have  thus  far  referred  to  field  or  pot-culture  experiments 
mainly  to  cite  the  existing  evidence  concerning  the  possibility  and 
practicability  of  using  methods  or  materials  regarding  which  the 
scientific,  agricultural,  and  commercial  interests  are  not  agreed. 

Before  taking  up  a  study  of  various  factors  that  influence  crop 
production,  including  the  use  of  special  fertilizers  for  special  soils 
and  crops,  it  seems  wise  to  consider  in  detail  the  results  of  some  of 
the  long-continued  field  experiments  with  general  farm  crops  on 
ordinary  normal  soils;  and,  after  wandering  through  the  wilder- 
ness of  the  last  chapter,  the  seeker  after  truth  will  welcome  the 
positive  data  from  thoroughly  scientific  cultural  investigations,  not 
from  20-day  cultures  in  pound  pots  or  water  extracts  or  even  from 
single-year  tests,  but  the  definite  yields  of  mature  crops  year  after 
year  for  twenty,  thirty,  and  even  for  sixty  years. 

At  the  same  time  the  author  begs  some  consideration  for  the 
question  if  we  need  prepare  to  avoid  in  America  a  repetition  of 
the  Dark  Ages  that  followed  the  high  civilization  of  the  Mediter- 
ranean countries,  until  relieved  by  the  discovery  of  the  New  World, 
and  that  still  exist  for  the  masses  in  Russia,  India,  and  China. 

343 


CPTAPTER  XIX 

THE  ROTHAMSTED  EXPERIMENTS 

ROTHAMSTED  is  the  oldest  agricultural  experiment  station.  It 
was  formally  established  in  1843,  nme  years  before  the  first  German 
experiment  station  was  started  at  Mockern  (Leipzig),  although 
some  experiments  had  been  conducted  at  Rothamsted  at  least  as 
early  as  1837,  and  more  extensive  field  experiments  were  begun  in 
1840.  The  published  records  report  all  of  the  crops  grown  on 
Broadbalk  field  since  1839,  and  the  exact  yields  of  produce  are 
recorded  since  1844,  so  that  the  records  now  cover  about  two  thirds 
of  a  century. 

It  was  in  1843  that  John  Bennet  Lawes,  the  proprietor  of  the 
Rothamsted  estate  and  founder  of  the  experiment  station,  secured 
the  services  of  Doctor  Joseph  Henry  Gilbert;  and  this  associa- 
tion, which  continued  to  the  end  of  the  century,  made  the  names, 
Lawes  and  Gilbert,  almost  synonymous  with  Rothamsted. 

The  earlier  extensive  investigations  of  De  Saussure  concerning 
the  mineral  constituents  of  plants,  followed  by  the  discussion  and 
further  investigations  of  Sir  Humphry  Davy  and  others,  and  the 
confident  announcement  of  well-defined  theories  by  Baron  Justus 
von  Liebig,  were  among  the  important  factors  that  influenced  the 
general  plans  that  were  adopted  for  the  Rothamsted  field  experi- 
ments. 

Lawes  and  Gilbert  did  not  concur  in  Liebig's  theory  so  far  as 
concerns  the  element  nitrogen,  and  the  central  plan  in  most  of 
the  Rothamsted  field  experiments  is  based  upon  this  difference 
of  opinion;  and,  while  the  accumulated  information  showing  the 
correctness  of  Lawes  and  Gilbert's  views  is  exceedingly  full  and 
complete,  some  other  important  facts  find  little  proof  in  the 
Rothamsted  data. 

344 


SIR  JOSEPH  HENRY  GILBERT  (1817-1901) 


THE    ROTHAMSTED   EXPERIMENTS  345 

Notwithstanding  this  somewhat  restricted  character  of  the 
general  plans,  the  records  of  Rothamsted  are  the  greatest  source  of 
knowledge  concerning  many  of  the  most  fundamental  problems 
of  soil  fertility;  and  in  justice  to  the  American  farmer  and  student 
of  permanent  agriculture,  the  author  cannot  do  less  than  to  repro- 
duce the  following  records  of  Rothamsted  investigations  that  seem 
to  bear  most  directly  upon  the  maintenance  of  soil  fertility  as 
measured  by  crop  yields: 

1.  Crops  grown  in  rotation  on  Agdell  field,  with  records  since 
1848. 

2.  Wheat  grown  continuously  on  Broadbalk  field,  with  records 
since  1844. 

3.  Wheat  alternating  with  fallow  on  Hoos  field,  with  records 
since  1851. 

4.  Barley  grown  continuously  on  Hoos  field,  with  records  since 
1851. 

5.  Potatoes  grown  continuously  on  Hoos  field,  twenty-six  years' 
records  (1876  to  1901). 

6.  Hay  grown  continuously  on  the  permanent  Park,  with  records 
since  1856. 

7.  Experiments  with  root  crops  on  Barn  field,  with  records  since 


This  mass  of  valuable  data  is  given  in  order  that  one  who  so 
desires  may  study  these  results  from  any  point  of  view  and  draw 
his  own  conclusions.  Space  is  also  taken  for  a  brief  discussion  of 
the  summaries  of  the  Rothamsted  laboratory  investigations,  and 
frequent  reference  to  these  data  must  be  made  for  proof  of  estab- 
lished principles. 

AGDELL  FIELD  ROTATION  CROPS  * 

The  Agdell  field  includes  two  series  of  six  plots  each.  On  one 
series  a  four-year  rotation  is  practiced,  as  follows  : 

First  year      ....  Swede  turnips  (rutabagas). 

Second  year  ....  barley. 

Third  year     ....  clover  (or  beans). 

Fourth  year  ....  wheat. 


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THE   ROTHAMSTED    EXPERIMENTS 


347 


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THE    ROTHAMSTED   EXPERIMENTS  353 

The  cropping  of  the  other  series  is  the  same,  except  that  fallow 
cultivation  is  practiced  instead  of  growing  clover  or  beans  the 
third  year.  In  the  tabular  statements  the  one  is  termed  the 
"  legume  "  system,  and  the  second  the  "  fallow  "  system. 

Crosswise,  Agdell  field  is  divided  into  three  sections  of  four  plots 
each.  One  section  is  unfertilized,  the  second  or  middle  section 
received  a  phosphorus  fertilizer  for  the  first  nine  rotations  (36 
years)  and  a  mixed  mineral  fertilizer,  including  phosphorus,  po- 
tassium, magnesium,  and  sodium,  during  the  last  six  rotations  (24 
years),  while  the  third  section  of  four  plots  has  received  both  the 
mixed  minerals  and  nitrogen  during  the  entire  sixty  ye'ars.  The 
fertilizers  are  all  applied  for  the  turnip  crop,  that  is,  only  once  every 
four  years. 

In  each  of  the  three  sections  two  plots  (one  legume  and  one  fal- 
low) have  had  the  turnip  crops  all  removed  (leaves  and  roots) ; 
while  the  other  two  plots  (one  legume  and  one  fallow)  have  had  the 
turnips  all  fed  off  by  sheep,  all  other  crops  having  been  removed 
from  all  plots  as  regularly  harvested.  In  1904  the  plan  was  adopted 
of  removing  the  turnips  from  all  of  the  plots,  thus  simplifying  the 
experiments  as  shown  in  the  tables.  In  1850,  only,  clover  was 
grown  on  the  entire  field,  including  the  series  since  in  fallow  every 
four  years.  The  twelve  individual  plots  were  each  one  fifth  acre 
in  size  and  nearly  square;  so  that,  as  conducted  since  1904  (or 
evidently  since  1901),  the  six  individual  plots  are  each  two  fifths 
acre  in  size  and  about  twice  as  long  as  wide. 

In  1848  Norfolk  white  turnips  were  grown  on  the  "  legume  " 
series  and  Swede  turnips  on  the  "  fallow  "  series.  The  exact 
yields  are  recorded  in  Tables  52  and  53;  but  in  computing  the 
average  yields  for  the  first  twenty  years  (5  rotations)  the  1848 
yields  from  the  fallow  series  were  used  for  both  series,  as  otherwise 
the  averages  would  not  be  comparable. 

The  clover  was  regularly  cut  twice  during  the  season  (three 
times  in  1874).  Undoubtedly  the  frequent  failure  of  the  clover1 
crop  has  to  a  considerable  extent foeen  caused  by  clover  "sickness." 

1  For  many  years  the  best  farmers  of  England  and  Continental  Europe  have 
practiced  the  substitution  of  some  other  legume,  as  beans,  yellow  trefoil,  etc.,  in 
alternate  rotations,  thus  seeding  clover  on  the  same  land  only  once  in  about  eight 
years. 


354    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

The  fertilizers  applied  per  acre  every  four  years  (for  the  turnip 
crop  only)  have  been  about  as  follows,  where  used: 

(a)  FERTILIZERS  FOR  AGDELL  FIELD,  POUNDS  PER  ACRE,  1892  AND 

PREVIOUSLY 


ELEMENTS  AND  MATERIALS 

UNFERTILIZED 

MINERALS 
(Phosphate  only 

MINERALS  AND 

previous  to  1884) 

Nitrogen             .... 

None 

None 

140 

Phosphorus    

None 

28 

45 

Potassium      

None 

125 

147 

Ammonium  sulfate      .     . 

None 

None 

IOO 

Ammonium  chlorid     .     . 

None 

None 

IOO 

Rape  cake      

None 

None 

2000 

Acid  phosphate  .... 

None 

350 

35° 

Potassium  sulfate    .     .     . 

None 

300 

300 

Magnesium  sulfate      .     . 

None 

IOO 

IOO 

Sodium  sulfate   .... 

None 

200 

2OO 

(b)  FERTILIZERS  FOR  AGDELL  FIELD,  POUNDS  PER  ACRE,  1896  AND  SINCE 


Nitrogen    

None 

None 

1  4O 

Phosphorus    

None 

40 

57 

Potassium      

None 

2IO 

232 

Ammonium  sulfate      .     . 

None 

None 

IOO 

Ammonium  chlorid     .     . 

None 

None 

IOO 

Rape  cake      

None 

None 

20OO 

Acid  phosphate  .... 

None 

500 

500 

Potassium  sulfate    .     .     . 

None 

500 

500 

Magnesium  sulfate      .     . 

None 

200 

2OO 

Sodium  sulfate   .... 

None  • 

IOO 

IOO 

Exceptions  to  these  tabular  statements  are  as  follows: 

In  1848,  about  40  pounds  of  nitrogen,  20  pounds  of  phosphorus, 
and  60  pounds  of  potassium  were  applied,  with  no  magnesium  or 
sodium  salts. 

In  1852,  about  30  pounds  of  phosphorus  and  only  100  pounds  of 
sodium  sulfate  were  applied,  otherwise  the  applications  for  1852 
were  the  same  as  shown  in  table,  except  as  explained  below. 

In  1884,  the  applications  of  alkali  minerals  were  made  for  the 
first  time  to  the  middle  section  and  for  that  year  were  double  the 


THE    ROTHAMSTED    EXPERIMENTS  355 

regular  amounts;  that  is,  600  pounds  of  potassium  sulfate,  200 
pounds  of  magnesium  sulfate,  and  400  pounds  of  sodium  sulfate. 

In  1896  and  in  1900,  600  pounds  of  basic  slag  phosphate  were 
applied  instead  of  500  pounds  of  acid  phosphate. 

The  sixty  years'  data  from  Agdell  field  are  exceedingly  valuable 
in  the  study  of  many  important  soil  fertility  problems.  No  ex- 
haustive discussion  can  be  given  here,  but  these  results  will  be 
referred  to  for  many  years  at  least  as  the  greatest  source  of  informa- 
tion concerning  the  effect  of  long-continued  crop  rotation.  A  few 
of  the  plainly  indicated  conclusions  may  be  noted. 

(1)  On  the  unfertilized  land  the  rotation  of  crops  does  not  main- 
tain the  fertility  of  the  soil,  the  yields  of  every  crop  having  de- 
creased with  the  possible  exception  of  beans.  The  yield  of  Swede 
turnips  dropped  from  about  10  tons  per  acre  in  1848  to  less  than 
2  tons  in  1852,  and  never   equaled  3  tons  per  acre  afterward. 
That  is  to  say,  the  turnips  have  always  been  grown  at  a  loss  since 
the  first  year,  the  best  yields  being  scarcely  worth  harvesting.  The 
barley  yields  have  decreased  from  more  than  40  bushels,  1849,  to 
15  bushels  as  an  average  of  the  last  20  years,  but  the  decrease 
has  been  very  gradual.  The  yield  of  legumes  has  been  very  irregu- 
lar, but,  with  the  exception  of  the  beans  in  1898,  has  markedly 
decreased,  the  clover  from  2.8  tons  in  1850  to  less  than  one  half 
ton  per  acre  as  an  average  of  the  crops  grown  during  the  third 
2o-year  period. 

The  yield  of  wheat  has  been  greatly  influenced  by  several  condi- 
tions, but  during  the  sixty  years  has  decreased  as  an  average  by 
8  bushels  in  the  legume  system  and  by  16.5  bushels  in  the  fallow 
system,  if  we  assume  that  the  difference  between  the  averages  for 
the  first  20  years  and  the  last  20  years  represents  the  decrease  of 
40  years.  The  lowest  average  yield  is  for  the  second  20  years,  but 
this  period  includes  the  abnormally  low  yields  of  1879  (when  the 
best  fertilized  plots  averaged  only  13.5  bushels)  and  two  other 
rather  poor  years. 

It  should  be  kept  in  mind,  too,  that  the  wheat  crop  comes  in  the 
next  year  after  legumes  or  fallow,  and  thus  has  the  most  favored 
place  in  the  rotation. 

(2)  The  application  of  mineral  plant  food  has  as  an  average  main- 
tained the  yields  of  legumes  and  of  the  following  wheat  crops. 


356    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

Even  the  yield  of  turnips  has  been  fairly  good  and  practically 
maintained  since  1852  in  the  legume  system,  but  it  should  be  noted 
that  the  yield  of  Swede  turnips  fell  off  nearly  10  tons  from  1848  to 
1852  (see  fallow  series  only  for  Swedes  in  1848).  In  case  of  the 
barley  the  influence  of  the  legumes  grown  three  years  before  is 
less  apparent,  and  the  barley  yields  have  decreased  during  the 
sixty  years  by  22  bushels  in  the  legume  system  and  by  31  bushels 
in  the  fallow  system,  if  we  consider  that  the  averages  for  the  first 
and  third  2o-year  periods  are  40  years  apart. 

(3)  Where  both  minerals  and  nitrogen  have  been  applied  (al- 
ways to  the  turnip  crop  only),  the  yield  of  turnips  has  been  appre- 
ciably increased;  and,  if  allowance  be  made  for  the  failure  of  1868, 
the  increase  has  been  somewhat  regular;    while  the  barley  crop, 
which  follows  the  turnips,  has  apparently  suffered  approximately 
in  proportion  to  the  increasing  drafts  upon  the  soil  by  the  turnips, 
and  with  as  near  approach  to  regularity.  The  fact  that  this  marked 
decrease  in  yield  appears  in  the  barley  straw  as  well  as  in  the  grain 
clearly  indicates  that  the  abundant  supplies  of  minerals  applied 
and   liberated  from   the  soil  make  it  possible  for  the  enormous 
turnip  crop  to  appropriate  so  much  of  the  available  nitrogen  supply 
that  the  quick-growing  spring  barley  is  limited  in  yield  by  lack  of 
nitrogen.   In  the  case  of  the  legumes  the  average  yields  have  dis- 
tinctly decreased  where  commercial  nitrogen  has  been  supplied. 
This  raises  the  question  whether  the  larger  crops  of  turnips  and 
barley  where  nitrogen  was  supplied  have  not  removed  such  large 
amounts  of  the  mineral  elements  that  the  yield  of  the  legumes 
(which  have  power  to  balance  their  own  nitrogen  ration)  is  thereby 
limited.    In  this  connection  it  may  be  noted  that,  as  an  average,  the 
yields  of  both  clover  and  beans  have  been  better  where  the  full 
minerals  alone  are  applied  (middle  section  since  1884)  than  where 
nitrogen  also  has  been  added.  The  yield  of  wheat  following  the 
legumes  has  been  well  maintained,  not  only  where  both  minerals 
and   nitrogen  are  applied,   but   also  where   minerals   alone  are 
used. 

(4)  On  the  unfertilized  land  the  fallow  system  has  given  better 
average  yields  of  turnips,  of  barley,  and  of  wheat  than  the  legume 
system,  throughout  the  entire  sixty  years,  except  for  the  wheat 
in  the  last  twenty.  The  fallow   system  also  gave  better  results 


THE    ROTHAMSTED    EXPERIMENTS  357 

on  the  phosphorus  plots  with  wheat  and  turnips,  and  practically 
the  same  yields  of  barley,  as  the  legume  system,  clearly  indicating 
that  where  the  soil  contains  a  fair  supply  of  nitrogen  in  proportion 
to  its  phosphorus  content  the  legume  crops  add  little  if  any  nitro- 
gen to  the  soil  in  excess  of  what  they  take  from  the  soil,  when  the 
regular  legume  crops  are  all  removed.  Ultimately,  however,  with 
the  continued  reduction  of  the  absolute  or  relative  supply  of  nitro- 
gen, in  comparison  with  other  essential  elements,  a  point  is  reached 
below  which  the  legumes  leave  in  the  roots  and  stubble  more  nitro- 
gen than  they  have  taken  from  the  soil.  In  soils  practically  devoid 
of  available  nitrogen  only  legumes  can  be  grown,  and  their  total 
content  of  nitrogen  must,  of  course,  be  taken  from  the  air. 

It  is  evident  that  nitrogen  has  become  so  depleted  in  the  unfer- 
tilized land  that  the  legume  residues  are  now  furnishing  the  wheat 
crop  with  some  nitrogen  taken  from  the  air,  but  this  effect  does  not 
extend  to  the  turnips  or  barley  crop.  On  the  other  hand,  where  an 
abundant  supply  of  minerals  makes  possible  the  production  of 
large  crops  of  legumes,  the  atmospheric  nitrogen  stored  in  the 
legume  crop  residues  (or  possibly  gathered  subsequently  as  sug- 
gested elsewhere)  not  only  maintains  the  yield  of  wheat  but  mark- 
edly affects  both  the  turnips  and  the  barley,  although  the  yield  of 
barley  is  steadily  decreasing. 

As  a  general  average  on  unfertilized  land  the  wheat  after  clover 
or  beans  has  yielded  about  10  per  cent  less  than  after  fallow;  but 
the  clover  residues  have  increased  the  yield  of  wheat  by  18  per  cent 
on  the  mineral  plots  and  by  13  per  cent  on  the  plots  receiving 
minerals  and  nitrogen,  compared  with  the  fallow  system;  whereas 
the  wheat  yields  after  beans  have  averaged  less  than  after  fallow 
on  all  plots.  These  results  are  in  accord  with  the  data  already 
given,  showing  that  the  roots  and  stubble  of  annual  legumes,  such 
as  cowpeas  and  soy  beans,  contain  much  less  nitrogen  and  organic 
matter  than  the  roots  and  residues  of  red  clover,  alfalfa,  and  sweet 
clover. 

(5)  The  fallow  system  is  unquestionably  very  exhaustive  of  the 
soil's  supply  of  nitrogen.  During  the  first  twenty  years  the  fallow 
system  produced  as  an  average  larger  crops  than  the  legume 
system,  but  the  decrease  in  yield  under  the  fallow  system  has  in 
most  cases  been  more  marked  than  under  the  legume  system. 


358    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

This  is  especially  noticeable  on  the  mineral  section,  where  best 
provision  is  made  for  rapidly  exhausting  the' nitrogen  by  removing 
other  limits  to  crop  production.  With  barley  under  the  fallow 
system  the  yield  for  the  last  twenty  years  averages  no  more  where 
minerals  are  supplied  than  where  no  fertilizer  is  used,  thus  indi- 
cating the  same  nitrogen  limit  for  that  crop,  and  emphasizing  the 
fact  that  no  amount  of  phosphorus  or  other  elements  can  increase 
the  yield  of  crops  where  nitrogen  has  become  the  limiting  element. 
In  the  case  of  wheat,  the  yield  is  still  greater  where  the  minerals  are 
supplied,  because  wheat  is  the  first  crop  grown  after  the  year  of  fallow 
cultivation,  the  principal  effect  of  which  is  to  liberate  nitrogen  from 
the  residue  still  contained  in  the  soil  humus;  and  whatever  weeds  are 
allowed  to  grow,  during  the  fallow  year  or  other  years,  will  help  to 
save  soluble  nitrogen  from  loss  in  drainage  water;  and  if  the  volun- 
teer herbage  includes  any  legume  plants,  some  atmospheric  nitrogen 
would  thus  be  added.  Of  course  if  any  growth  of  this  character 
were  larger  on  the  mineral  plots  than  on  the  unfertilized  land,  the 
effect  would  be  greatest  on  those  plots  in  the  increased  growth  of 
the  wheat,  turnips,  and  barley. 

It  is  pointed  out  by  Dyer  (Results  of  Investigations  on  the  Roth- 
amsted  Soils,  Bulletin  106  of  the  Office  of  Experiment  Stations, 
United  States  Department  of  Agriculture)  that  where  barley  is 
grown  every  year  on  Hoos  field  the  most  common  weed  on  the  plot 
receiving  minerals  without  nitrogen  is  yellow  trefoil,  which  grows 
even  while  the  barley  crop  is  supposed  to  occupy  the  land;  and  that 
Sir  Henry  Gilbert  had  expressed  the  opinion  that  very  appreciable 
quantities  of  nitrogen  were  added  to  the  soil  by  that  leguminous 
plant,  which  grows  persistently  as  a  weed  on  that  plot  despite  the 
efforts  to  eradicate  it. 

Since  the  above  was  written,  Director  Hall,  of  Rothamsted,  has 
kindly  furnished  the  specific  information  that  the  fallow  portion  of 
Agdell  field  is  kept  plowed,  and  is  therefore  practically  free  from 
weeds  during  that  year;  but  when  wheat  is  grown,  "  there  is  a  good 
deal  of  wild  yellow  trefoil,  particularly  in  certain  seasons,  and 
on  the  plots  receiving  mineral  manures  only."  He  states  that  this 
trefoil  was  so  abundant  in  1907  that  after  the  wheat  harvest  he 
had  it  cut  and  weighed  separately,  and  found  that  the  amounts 
per  acre  (including,  presumably,  the  wheat  stubble  etc.)  were 


THE    ROTHAMSTED    EXPERIMENTS  359 

1330  pounds  on  the  unfertilized  land,  2633  pounds  where  minerals 
alone  are  used,  and  718  where  both  minerals  and  nitrogen  are 
applied.  These  figures  relate  only  to  the  fallow  plots.  On  the 
legume  plots  there  was  very  much  less  trefoil.  Director  Hall 
states  that  the  amounts  that  grew  on  the  fallow  plots  in  1907  are 
rather  exceptional,  but  that  in  every  crop  of  wheat  or  barley  there 
is  some  of  this  wild  legume,  "  which  must  have  some  influence 
upon  the  nitrogen  content  of  the  soil." 

(6)  The  effect  of  feeding  off  the  turnips  by  pasturing  with  sheep 
is  a  distinct  benefit  to  succeeding  crops  wherever  the  yield  of  tur- 
nips amounts  to  much.  This  effect  is  most  marked,  of  course,  on 
the  mineral  plots,  where  nitrogen  is  very  deficient,  and  it  is  also 
most  marked  on  the  barley  crop,  which  follows  immediately  after 
the  turnips,  although  the  influence  can  usually  be  seen  on  the 
legumes  and  wheat,  and  even  on  the  following  turnip  crop. 

Before  leaving  Agdell  field  we  may  well  try  to  view  these  results 
from  the  financial  standpoint,  particularly  during  the  last  twenty 
years,  because  the  world  affords  no  other  data  from  crop-rotation 
experiments  in  which  can  be  studied  2o-year  averages  secured  after 
a  preliminary  period  of  forty  years.  (See  also  page  419.) 

In  Table  59  the  turnips  are  valued  at  $1.40  per  ton,  the  clover 
hay  at  $6  per  ton,  the  barley  at  50  cents  a  bushel,  the  beans  at 
$1.25  a  bushel,  and  the  wheat  at  70  cents  a  bushel.  At  these  prices, 
the  turnips  and  beans  were  more  valuable  per  acre  than  the  wheat. 
Nitrogen  is  figured  at  15  cents  a  pound,  phosphorus  at  12  cents, 
and  potassium  at  6  cents;  and  it  is  assumed  that  the  magnesium 
and  sodium  salts  cost  the  same  as  the  extra  salts  in  kainit  at  $15 
a  ton.  These  various  prices  may  be  modified  and  the  results  re- 
calculated to  fit  different  local  conditions. 

No  values  are  allowed  for  the  straw  of  barley,  beans,  or  wheat, 
or  for  turnip  leaves;  but  in  computing  the  value  of  increases  it  is 
assumed  the  increase  in  these  by-products  would  be  worth  as  much 
as  the  extra  cost  of  harvesting,  threshing,  etc. 

At  the  prices  used  in  Table  59,  the  use  of  minerals  in  the  legume 
system  has  more  than  doubled  the  value  of  the  crops  produced 
during  the  last  20  years,  the  average  of  which  really  represents  the 
condition  just  fifty  years  from  the  beginning,  in  1848.  While  the 
effect  upon  turnips  is  to  change  a  practical  failure  into  a  crop  which 


almost  pays  for  the  minerals  the  first  year,  the  residual  effect 
upon  the  other  crops  is  to  nearly  double  their  total  value. 

TABLE  59.   ROTATION  CROPS  ON  AGDELL  FIELD,  ROTHAMSTED 
Average  per  Acre  of  Third  2o-year  Period,  1888  to  1907 


Son.  TREATMENT 

UNFERTILIZED 

MINERALS 

MINERALS  AND 
NITROGEN 

System  

Legume 

Fallow 

Legume 

Fallow 

Legume 

Fallow 

Swede  turnips,  pounds  . 
Barley,  bushels     .     .     . 
Clover  hay  (3),  pounds 
Beans  (2),  bushels    .     . 
Wheat,  bushels     .     .     . 

967 

13-7 
770 

16.0 
24-3 

2502 
15-9 

25275 
22.2 

3895 
28.3 
38.4 

20629 
15-9 

4I731 
29.2 

3479 
19.6 

36-4 

46523 
24.1 

23-5 

28.0 

32.1 

Swede  turnips,  value 
Barley,  value   .... 
Clover,  value  (f)  .     .     . 
Beans,  value  (I)   .     .     . 
Wheat,  value   .... 

Value  in  four  years  .     . 

$    .68 
6.85 

i-39 
8.00 
17.01 

$  i-75 
7-95 

$I7-69 
II.  IO 
7-OI 

I4-I5 
26.88 

$14.44 

7-95 

$29.21 
14.60 
6.26 
9.80 
25.48 

$32.57 
12.05 

16.45 

19.60 

22-47 

S33-83 

$26.15 

$76-83 

$41.99 

$35.35 

$67.09 

Value  of  increase               

$43-00 
17.88 

$15.84 
17.88 

$5i-52 
42.24 

$40.94 
42.24 

Cost  of  treatment               

Profit  or  loss  (  —  )     

$25.12 

-$2.04 

$9.28 

-$1-30 

In  this  system  the  minerals  have  paid  for  themselves  and  made 
a  net  profit  of  140  per  cent  on  the  investment.  They  have 
also  fully  maintained  the  average  yield  of  legumes,  wheat,  and 
turnips  since  1852,  but  the  system  fails  to  maintain  the  supply 
of  nitrogen,  and  because  of  this  the  barley  has  markedly  de- 
creased in  yield. 

One  may  assume  with  reasonable  confidence  that  if  the  turnip 
leaves,  the  wheat  and  barley  straw,  the  bean  straw,  and  perhaps 
part  of  the  clover  crop,  had  been  returned  to  this  land  to  furnish 
nitrogen  and  decaying  organic  matter,  the  barley  yields  might 
also  have  been  maintained  and  the  turnip  crops  kept  equal  to  that 
of  1848,  thus  providing  a  permanent  system;  whereas,  under  the 
system  practiced,  it  seems  certain  that  the  yield  of  turnips  must 
decrease  in  time;  and  in  the  opinion  of  the  author  the  nitrogen 
supplied  by  the  legume  residues  will  ultimately  be  insufficient  to 


THE    ROTHAMSTED    EXPERIMENTS  '  361 

maintain  the  yield  of  wheat,  unless  the  azotobacter  or  some  other 
nitrogen-fixing  agency  is  more  efficient  than  our  present  knowl- 
edge indicates;  or  unless  the  leguminous  weeds  are  allowed  to 
grow  in  sufficient  quantity  to  furnish  and  maintain  the  nitrogen 
balance. 

The  application  of  commercial  nitrogen  does  not  solve  the  prob- 
lem for  present  conditions  of  general  farming  in  the  United  States, 
because  at  reasonable  average  prices  the  addition  of  $21  of  nitro- 
gen has  increased  the  average  crop  values  by  only  $8.52  under  the 
only  profitable  system,  notwithstanding  the  additional  phosphorus 
and  potassium  also  supplied  in  the  rape  cake.  As  would  be  ex- 
pected, the  applied  nitrogen  produced  a  more  marked  effect  in  the 
fallow  system,  which  is  so  very  exhaustive  of  the  soil  nitrogen; 
and  in  this  case  the  minerals  and  nitrogen  produced  slightly  less 
loss  than  the  minerals  alone;  so  that,  if  produce  from  the  mineral 
plots  could  be  figured  at  prices  which  would  show  some  profit,  it 
would  then  be  profitable  to  add  the  ammonium  salts  and  rape 
cake. 

The  question  remains  whether  a  liberal  supply  of  decaying  or- 
ganic matter  in  connection  with  the  phosphorus  fertilizer  would 
not  have  rendered  the  use  of  potassium  sulfate  and  other  salts 
unnecessary  or  unprofitable,  especially  since  much  of  the  potassium 
removed  in  crops  would  be  returned  in  the  straw  and  leaves. 
Since  there  has  been  a  recent  change  on  Agdell  field,  by  which  the 
practice  of  pasturing  off  the  turnips  has  been  discontinued, 
Director  Hall  is  considering  the  plan  of  applying  to  the  "  fed  " 
plots,  in  addition  to  the  regular  fertilizers,  amounts  of  farm 
manure  equivalent  to  the  root  crops,  straw,  and  clover  hay  pro- 
duced on  those  respective  plots,  because  that  would  more  closely 
agree  with  ordinary  farming  practice  in  England. 

In  passing  from  the  Agdell  rotation  field  to  the  continuous 
wheat-growing  on  Broadbalk  field,  attention  is  called  to  the  fact 
that  as  an  average  of  the  third  2o-year  period  the  unfertilized 
plot  3  on  Broadbalk  produced  12.2  bushels  of  wheat  per  acre  (see 
Table  62),  which  at  70  cents  a  bushel  would  be  worth  $34.16  in 
four  years;  whereas  the  average  value  of  the  rotation  crops 
produced  on  unfertilized  land  during  four  years  (as  an  average 
of  the  third  2o-year  period  on  Agdell  field)  was  only  $33.83  in  the 


362     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

legume  system,  and  $26.15  in  the  fallow  system,  at  the  prices  used 
in  Table  59.   (See  also  comparative  statement  of  prices  on  page  359.) 


17.58 


TURNIP  CROP  OF  1908  ON  AGDELL  FIELD,  ROTHAMSTED;  6isx  CROP  IN  4-YEAR 
ROTATION;  TONS  PER  ACRE 


Unfertilized 


Mineral  plant  food 


Minerals  and  nitrogen 


Counting  from  the  left,  lots  1,3,  and  5  were  grown  on  land  where  the  rotation  is 
turnips,  barley,  clover,  and  wheat,  while  lots  2,  4,  and  6  were  grown  on  land  where  the 
rotation  is  turnips,  barley,  fallow,  and  wheat.  The  six  lots  were  all  produced  on  plots  of 
ground  of  equal  size.  Plots  i  and  2  have  received  no  fertilizer.  Plots  3  and  4  received 
only  a  phosphorus  fertilizer  for  the  36  years,  1848  to  1883,  but  since  that  time  they 
have  received  mixed  minerals,  including  phosphorus,  potassium,  magnesium,  and  sodium. 
(The  average  yield  of  turnips  in  1880  was  i%  tons  for  plots  i  and  2,  and  the  average 
yield  of  plots  3  and  4  for  the  same  year  was  1 2%  tons  per  acre.)  Plots  5  and  6  have  re- 
ceived mixed  minerals  and  nitrogen  since  1848. 

These  are  the  rotation  experiments  referred  to  by  Professor 
Whitney  on  page  22  of  U.  S.  Farmers'  Bulletin  257,  as  follows: 

"In  other  experiments  of  Lawes  and  Gilbert  they  have  maintained  for  fifty 
years  a  yield  of  about  30  bushels  of  wheat  continuously  on  the  same  soil  where 
a  complete  fertilizer  has  been  used.  They  have  seen  their  yield  go  down  where 
wheat  followed  wheat  without  fertilizers  for  fifty  years  in  succession  from  30 
bushels  to  12  bushels,  which  is  what  they  are  now  getting  annually  from  their 
unfertilized  wheat  plot.  With  a  rotation  of  crops  without  fertilizers  they  have 
also  maintained  their  yield  for  fifty  years  at  30  bushels,  so  that  the  effect  of  rota- 
tion has  in  such  case  been  identical  with  that  of  fertilization." 

In  commenting  upon  these  statements,  Director  A.  D.  Hall,  of 
the  Rothamsted  Experiment  Station,  says: 

"I  cannot  agree  with  Professor  Whitney's  reading  of  the  results  on  the 
Agdell  field  in  the  least.  The  figures  he  quotes  for  wheat  are  hardly  justifiable 
as  approximations,  and  are  in  spirit  contrary  to  the  general  tenor  of  the  par- 
ticular experiment.  In  my  opinion  the  results  on  the  Adgell  rotation  field  are 
directly  contrary  to  Professor  Whitney's  idea  that  rotation  can  do  the  work  of 
fertilizers."  (See  Report  of  the  Committee  of  Seven,  including  Woll  of  Wiscon- 
sin, Van  Slyke  of  New  York,  Lipman  of  New  Jersey,  Davidson  of  Virginia, 


THE    ROTHAMSTED    EXPERIMENTS  363 

Ross  of  Alabama,  Peter  of  Kentucky,  and  Penny  of  Pennsylvania,  appointed 
by  the  Association  of  Official  Agricultural  Chemists,  "to  consider  in  detail 
the  questions  raised";  published  in  full  in  Circular  123  of  the  University  of 
Illinois  Agricultural  Experiment  Station.) 


BROADBALK  FIELD 

Undoubtedly  Broadbalk  is  the  best-known  experiment  field  in 
the  world,  and  plots  2  and  3  are  the  most  often  referred  to.  While 
the  continuous  growing  of  wheat  on  the  same  land  is  not  to  be 
considered  the  best  practice,  the  records  given  in  Table  60  show 
very  clearly  that  it  is  possible.  These  plots  are  compared  with 
most  of  the  others  for  a  period  of  55  years.  Perhaps  the  most 
interesting  and  instructive  results  are  the  average  yields  of  12.9 
bushels  on  the  unfertilized  land,  35.5  bushels  with  farm  manure, 
and  37.1  bushels  with  the  heaviest  applications  of  commercial 
plant  food. 

Plots  5,  6,  7,  and  8  differ  only  in  the  amount  of  nitrogen  applied; 
and,  with  successive  additions  of  43  pounds  of  nitrogen  per  acre, 
the  average  yields  increase  from  14.9  bushels  with  no  nitrogen 
applied,  to  23.8  bushels  with  43  pounds  of  nitrogen,  to  32.8  bushels 
with  86  pounds  of  nitrogen,  and  to  37.1  bushels  with  129  pounds 
of  nitrogen.  The  average  yield  of  55  crops  is  only  2  bushels  more 
per  acre  where  792  pounds  of  mixed  mineral  fertilizers  have  been 
applied  every  year  than  where  no  fertilizer  of  any  kind  has  been 
used.  These  data  are  in  striking  contrast  with  the  results  from 
Agdell  field,  where,  as  an  average  of  the  last  20  years,  the  increase 
with  minerals  alone  is  83  per  cent  of  the  total  increase  with  min- 
erals and  nitrogen,  while  on  Broadbalk  the  minerals  alone  have 
produced  an  average  increase  which  is  only  8  per  cent  of  the  in- 
crease from  minerals  and  nitrogen  (plot  8). 

With  the  fallow  system  on  Agdell  field  the  results  are  tending 
in  the  same  direction  as  those  from  Broadbalk,  and  most  markedly, 
of  course,  where  all  crops  were  removed. 

This  must  emphasize  a  fact  which  it  is  exceedingly  important  to 
keep  in  mind  while  studying  the  results  from  Broadbalk  field; 
and  indeed,  when  studying  the  data  from  not  only  the  Rothamsted 
fields  but  from  nearly  all  of  the  oldest  soil  experiment  fields  in 


364    INVESTIGATION    BY   CULTURE   EXPERIMENTS 


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Minerals  (P,  K,  Mg,  Ca,  S 
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THE    ROTHAMSTED    EXPERIMENTS 


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NOTE.  Average  yields  of  straw  for  the  eight  years,  1844  to  1851,  were  2979  Ib.  from  plot  2,  also  1736  Ib.  from  plot  3,  and 
2654  Ib.  from  plot  10. 

1  Applied  in  alternate  years.  *  This  is  three  fourths  of  actual  yield  on  half  plots  after  fallow. 

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366    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

America  as  well;  namely,  that  practically  no  provision  has  been 
made  for  maintaining  any  adequate  supply  of  decaying  organic 
matter  in  the  soil,  in  consequence  of  which,  in  the  author's  opin- 
ion, the  soil  itself  becomes  practically  inactive,  and,  if  satisfactory 
crops  are  to  be  grown,  every  essential  element  of  plant  food  must 
be  supplied  artificially  in  readily  available  form. 

According  to  well-established  and  universally  accepted  physical 
laws,  a  solution  is  always  saturated  so  long  as  there  is  contact 
and  equilibrium  between  the  solution  and  the  undissolved  sub- 
stance ;  but,  in  the  author's  opinion,  this  law  of  solution  does  not 
apply  to  the  soil  mass  as  a  whole,  for  equilibrium  is  never  estab- 
lished in  the  soil  mass  as  a  whole.  In  the  unlimited  and  unquali- 
fied application  of  this  entirely  correct  solution  theory,  we  might 
say  that  the  peaty  swamp  lands  of  Illinois  have  direct  capillary 
connection  with  the  potassium  mines  of  Germany;  but  the  fact  is, 
that,  where  200  pounds  of  potassium  sulfate  per  acre  have  been 
applied  to  that  peaty  swamp  land  with  a  resultant  yield  of  more 
than  50  bushels  of  corn  per  acre,  the  crop  on  the  untreated  ad- 
joining land,  separated  only  by  a  half-rod  division  strip,  receives 
absolutely  no  benefit  because  of  any  capillary  connection,  and 
yields  less  than  5  bushels  of  corn  per  acre,  even  where  the  experi- 
ment is  continued  year  after  year. 

Even  regarding  the  Rothamsted  permanent  grass  plots,  which 
are  separated  only  by  a  line,  which  vary  in  soluble  fertilizers  re-, 
ceived  from  none  to  a  ton  per  acre  per  annum,  in  average  yield 
from  one  to  four  tons  of  hay  per  acre,  and  in  herbage  from 
strictly  nonleguminous  to  fifty  per  cent  of  legume  plants,  the  state- 
ment is  made  by  Director  Hall  that,  "although  the  treatment  has 
been  repeated  now  for  fifty-two  years,  the  dividing  line  between 
the  two  plots  remains  perfectly  sharp,  and  the  rank  herbage  pro- 
duced by  the  excess  of  nitrogenous  fertilizer  on  one  side  does  not 
stray  six  inches  over  the  boundary." 

Unquestionably  the  film  of  water  surrounding  a  soil  grain  be- 
comes a  saturated  solution  of  all  the  minerals  exposed  on  the 
surface  of  that  individual  particle,  but  this  solution  may  be  of 
different  composition  from  each  of  the  other  films  surrounding 
the  other  billion  or  more  soil  grains  which  may  exist  in  the  same 
cubic  inch  of  soil,  of  which,  perhaps,  only  one  in  a  thousand  con- 


THE    ROTHAMSTED    EXPERIMENTS  367 

tains  any  phosphorus,  for  example.  If  the  87  pounds  of  acid- 
soluble  phosphorus  contained  in  2  million  pounds  of  the  surface 
soil  of  an  acre  of  the  level  upland  "  barrens  "  of  the  Highland 
Rim  of  Tennessee  were  all  distributed  in  a  coating  of  uniform 
thickness  over  the  surfaces  of  all  the  soil  grains  in  the  stratum,  it 
is  very  possible  that,  if  all  other  essentials  were  provided  in  abun- 
dance or  perfection,  the  abundant  sunshine  and  rainfall  of  Ten- 
nessee would  bring  forth  from  that  soil  hundred-bushel  crops  of 
corn  for  three  successive  years,  or  possibly  longer,  because,  accord- 
ing to  the  Tennessee  Experiment  Station  (Bulletin  3,  Volume  X, 
1897),  there  are  61  pounds  of  acid-soluble  phosphorus  in  each 
2  million  pounds  of  the  subsoil. 

Absolute  science  shows  no  necessary  relation  between  the 
amount  of  potassium,  for  example,  that  may  be  dissolved  from 
100  grams  of  soil  by  500  grams  of  water,  during  twenty  minutes 
of  laboratory  manipulation,  and  the  amount  of  the  same  element 
that  a  corn  plant  may  secure  from  a  cubic  yard  of  earth  during 
the  four  months'  period  of  growth. 

Referring  again  to  the  Broadbalk  field  data,  it  will  be  seen 
that  even  where  86  pounds  of  nitrogen  are  applied  (plot  10),  the 
average  yield  is  only  20.4  bushels,  or  18.6  for  the  last  25  years; 
and  the  increase  of  6.6  bushels  by  nitrogen  alone  is  raised  to  21.2 
bushels  (or  to  33.2  bushels  per  acre)  when  both  nitrogen  and 
minerals  are  supplied.  Under  these  conditions,  nitrogen  and  phos- 
phorus are  powerless  to  maintain  the  yield  (see  plot  n);  for, 
although  the  soil  contains  abundance  of  potassium  and  other  less 
important  essential  elements,  there  is  evidently  but  little  action 
in  the  soil  by  which  they  can  be  made  available.  One  is  inclined, 
for  the  land's  sake,  to  wish  that  one  or  two  good  crops  of  clover 
might  be  plowed  under  on  plots  5  and  n,  were  it  not  for  the  fact 
that  these  plots  are  far  too  valuable  for  the  lessons  they  are  now 
teaching  to  justify  any  such  change. 

It  is  even  questionable  whether  the  effect  of  the  potassium  ap- 
plied to  plot  13  is  wholly  due  to  the  use  of  that  element  as  plant 
food,  or  perhaps  due  in  part  to  its  power  to  hold  other  elements, 
as  phosphorus,  in  available  form.  It  will  be  observed  that  during 
the  first  30  years  sodium  and  magnesium  salts  (applied  in  molec- 
ular proportions)  produced  essentially  the  same  increase  (about 


368    INVESTIGATION   BY   CULTURE    EXPERIMENTS 

5  bushels)  as  potassium  sulfate.  It  is  commonly  assumed  that  the 
effect  of  the  sodium  and  magnesium  salts  is  due  to  their  reaction 
with  insoluble  potassium  silicates  with  liberation  of  soluble  potas- 
sium, and  the  results  of  the  later  years  certainly  strongly  support 
that  view.  The  regularity  with  which  potassium  is  surpassing  so- 
dium and  magnesium  in  its  influence  upon  crop  yields  would 
even  lead  one  to  imagine  that  the  1907  yields  of  plots  12  and  13 
might  have  been  interchanged,  except  that  the  exceedingly  care- 
ful methods  of  the  Rothamsted  Station  makes  such  an  error  prac- 
tically impossible,  and  that  the  more  certain  explanation  lies  in 
the  enormous  variation  (which  every  experimenter  is  familiar 
with)  in  different  seasons  among  field  plots,  subject  to  so  many 
uncontrolled  and  uncontrollable  influences.  Compare,  for  example, 
plot  ii  with  plot  17  (minerals)  in  1904  and  1906. 

In  studying  plots  17  and  18,  it  should  be  understood  that  for  the 
1907  crop  (for  example)  the  minerals  only  were  applied  to  plot  17 
and  the  ammonium  salts  only  to  plot  18,  while  for  the  1908  crop 
the  ammonium  salts  only  were  applied  to  plot  17  and  the  minerals 
only  to  plot  1 8,  this  system  of  alternating  having  been  followed 
since  1852,  and  the  amounts  recorded  in  Table  60  for  these  two 
plots  are  thus  applied  biennially  and  not  annually. 

The  data  prove  conclusively  that  almost  none  of  the  applied 
nitrogen  remains  to  benefit  the  second  crop,  while  the  minerals 
remain  and  exert  marked  benefit  on  the  succeeding  crop.  Compare 
with  plot  7  (for  example),  which  receives  twice  as  much  minerals 
during  the  biennium. 

It  is  of  interest  to  note  that  in  the  dry  season  of  1893  (see 
rainfall  record,  Table  65)  the  farm  manure  plot  produced  12.5 
bushels  more  wheat  than  the  best  fertilized  plot  (No.  8),  while  as 
an  average  the  heaviest  applications  of  commercial  plant  food  have 
given  slightly  larger  yields  than  the  farm  manure,  and  the  difference 
in  favor  of  the  commercial  materials  seems  to  be  greater  in  wet  sea- 
sons. Thus,  in  1903,  plot  8  produced  6.1  bushels  more  than  plot  2. 
Compare  also  the  wet  year  of  1879  with  .the  dry  year  of  1898. 

It  must  be  understood,  of  course,  that  Broadbalk  field  is  de- 
signed to  secure  knowledge  and  establish  principles  rather  than 
to  serve  as  a  model  for  agricultural  practice.  Nevertheless,  it  is  of 
interest  to  apply  some  financial  measurements  to  the  results. 


THE  ROTHAMSTED    EXPERIMENTS  369 

Thus,  the  average  increase  of  22.6  bushels  resulting  from  the 
annual  application  of  15.7  tons  of  farm  manure  (14  tons  of  2240 
pounds)  would  be  worth  $15.82  at  70  cents  a  bushel.  In  other 
words,  manure  is  worth  $i  per  ton  for  use  at  this  rate  in  continu- 
ous wheat  culture. 

In  no  case  has  the  total  application  of  commercial  plant  food 
paid  for  its  cost  at  standard  prices;  and  rarely  has  any  addition 
paid  for  itself  in  increase  produced,  even  though  the  cost  of  other 
materials  be  disregarded.  We  may  reckon  $6.45  as  the  cost  of 
43  pounds  of  nitrogen,  $3.48  for  29  pounds  of  phosphorus,  $5.10 
for  85  pounds  of  potassium,  and  $8.98  for  the  full  minerals  (assum- 
ing that  the  magnesium  and  sodium  salts  can  be  bought  as  cheaply 
as  in  kainit  at  $15  a  ton  when  used  in  connection  with  sufficient 
potassium) . 

Thus  the  minerals'  alone  on  plot  5  produced  an  average  increase 
of  2  bushels,  worth  $1.40,  at  a  cost  of  $8.98,  and  of  course  any 
application  made  in  addition  to  minerals  must  pay  for  this  deficit 
of  $7.58  as  well  as  for  its  own  cost  before  there  could  be  any  profit. 
But  if  we  disregard  this  deficit,  we  find  that  $6.45  in  nitrogen  on 
plot  6  produced  8.9  bushels  increase,  worth  only  $6.23;  that  a 
second  $6.45  in  nitrogen  on  plot  7  produced  a  further  increase  of 
9  bushels,  worth  $6.30;  and  that  the  third  $6.45  invested  in  nitro- 
gen on  plot  8  produced  4.3  bushels  of  wheat,  worth  $3.01. 

We  may -also  begin  our  computations  with  the  400  pounds  of 
ammonium  salts  applied  to  plot  10,  on  which  86  pounds  of  nitro- 
gen (only  12  pounds  more  than  would  be  contained  in  a  5o-bushel 
crop),  costing  $12.90,  produced  7.5  bushels  increase,  worth  $5.25, 
thus  placing  a  deficit  of  $7.65  against  any  additional  treatment. 
The  increase  from  minerals  alone  was  worth  only  $1.40,  but  with 
nitrogen  provided  (on  plot  7)  the  minerals  costing  $8.98  produced 
$8.68  increase  in  the  value  of  the  crop,  thus  adding  only  30  cents 
to  the  deficit;  while  acid  phosphate  on  plot  n  added  $1.31,  mak- 
ing a  total  deficit  of  $8.96  for  nitrogen  and  phosphorus,  which, 
however,  was  reduced  to  $8.60  by  the  potassium  on  plot  13.  The 
plan  of  the  Broadbalk  experiment  affords  no  answer  to  the  question 
as  to  how  much  effect  would  be  produced  by  potassium  salt  by 
itself,  but  some  extensive  American  experiments  hereinafter  dis- 
cussed indicate  that  by  itself  the  potassium  sulfate  would  have 


370    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

been  much  less  effective  than  where  liberal  provision  is  also  made 
for  phosphorus  and  nitrogen. 

The  sodium  sulfate  and  the  magnesium  sulfate  produced  more 
than  three  fourths  as  much  increase  as  the  potassium  sulfate,  and 
may  have  been  profitable  in  themselves,  but  even  if  they  cost 
nothing,  they  would  not  overcome  one  half  of  the  deficit  standing 
against  the  treatment  with  nitrogen  and  phosphorus. 

In  the  last  five-year  average,  potassium  pays  a  profit  of  $3.93, 
but  meanwhile  the  deficit  on  plot  n  has  increased  to  $10.43,  the 
soil  having  become  so  deficient  in  decaying  organic  matter  that 
only  half  a  crop  can  be  produced  with  the  amount  of  potassium 
liberated  from  the  immense  supply  still  remaining  in  the  soil, 
even  though  phosphorus  and  nitrogen  are  supplied  in  available 
form.  The  other  sulfates  have  become  only  half  as  effective  as  the 
potassium  salt,  and  the  fact  that  sodium  produces  the  same  effect 
as  magnesium  strengthens  the  common  belief  that  their  chief 
action  is  to  liberate  potassium  from  the  insoluble  silicates. 

Under  these  conditions,  it  ought  not  to  be  expected  that  decaying 
organic  matter  of  itself  would  liberate  sufficient  potassium  from  the 
soil  for  the  production  of  maximum  crops.  However,  any  system 
under  which  the  organic  matter  content  of  the  soil  can  be  main- 
tained in  optimum  amount  will  necessarily  return  to  the  soil  in 
the  organic  matter  most  of  the  potassium  taken  from  the  soil. 
On  the  other  hand,  all  of  the  crops  taken  from  plot  2  during  the 
55  years  have  removed  in  both  grain  and  straw  only  2330  pounds 
of  potassium  (based  upon  Rothamsted  analyses),  or  only  one 
fifteenth  as  much  as  was  contained  at  the  beginning  in  2  million 
pounds  of  the  fine  surface  soil.  In  other  words,  the  total  supply  of 
potassium  contained  in  2  million  pounds  of  the  soil  would  be 
sufficient  for  such  crops  (grain  and  straw)  for  800  years. 

The  55  crops  from  plot  2  have  removed  about  650  pounds  of 
phosphorus,  and  2  million  pounds  of  the  surface  soil  of  plot  3 
(unfertilized)  now  contain  only  980  pounds  of  phosphorus  soluble 
in  strong  nitric  or  hydrochloric  acid,  after  ignition,  and  reported 
by  Doctor  Bernard  Dyer  *  as  total  phosphorus.  Here  we  find  that 
the  phosphorus  actually  removed  in  55  crops  from  plot  2  is  two 

1  Bulletin  106,  Office  of  Experiment  Stations,  United  States  Department  of 
Agriculture. 


THE    ROTHAMSTED    EXPERIMENTS  371 

thirds  as  much  as  the  total  phosphorus  now  contained  in  the  plowed 
soil  of  the  adjoining  plot.  Furthermore,  the  surface  soil  of  the  farm 
manure  plot  to  the  same  depth  now  contains  1 700  pounds  of  total 
phosphorus.  Plots  5,  7,  n,  12,  13,  and  14  now  contain  as  much 
phosphorus  as  plot  2,  while  plots  4,  10  a,  and  10  b,  none  of  which  has 
received  any  phosphorus  fertilizer  during  the  55  years,  now  contain 
about  the  same  amount  as  plot  3. 

Because  of  the  extreme  difficulty  with  some  very  persistent 
weeds  on  the  unfertilized  land,  one  half  of  plot  3  was  fallowed  in 
1904  and  the  other  half  in  1905,  but  this  weed  trouble  is  now  being 
controlled  by  drilling  the  wheat  in  somewhat  wider  rows  and  hand 
hoeing  when  necessary.  Manifestly,  the  actual  yields  from  one 
half  of  plot  3  for  1905  and  from  the  other  half  for  1906  ought  not 
to  be  used  in  making  averages  for  wheat  after  wheat  every  year; 
but  it  will  be  seen  from  Table  63  that  the  average  yield  of  continu- 
ous wheat  is  about  three  fourths  of  the  yield  of  wheat  alternating 
with  fallow,  and  consequently  this  factor  has  been  employed  as 
stated. 

In  Table  62  are  given  the  actual  annual  yields  of  wheat  harvested 
from  certain  Rothamsted  plots  since  1844. 

Space  is  taken  for  these  complete  records  because  the  author 
feels  that  they  will  be  of  genuine  interest  to  the  more  careful 
readers,  and  also  because  every  reader  is  entitled  to  such  records 
of  these  oldest  and  most  valuable  soil  investigations,  in  order  that 
he  may  make  any  comparisons  that  may  be  desired.  Questions 
may  occur  to  the  reader  that  neither  the  author  nor  any  other 
writer  has  even  thought  of;  and,  since  these  are  the  longest  con- 
tinuous records  the  world  affords,  they  are  likely  to  furnish  the 
best  data  for  helping  to  solve  some  very  practical  questions.  For 
example,  is  it  a  true  saying  that,  as  a  rule,  poor  crops  are  followed 
by  good  crops  the  next  year?  If  so,  then  what  kind  of  a  crop  should 
follow  an  exception  to  this  rule;  that  is,  should  two  poor  crops  in 
succession  be  followed  by  an  .exceptionally  good  crop?  It  is  also 
said  that  an  extra  good  crop  is  likely  to  be  followed  by  another 
good  crop. 

One  might  eliminate  the  poorest  yield  or  the  best  yield  in  every 
eight-year  period,  for  example,  and  then  determine  if  the  average 


372 


INVESTIGATION   BY   CULTURE   EXPERIMENTS 


TABLE  62.   WHEAT  YIELDS  AT  ROTHAMSTED 
Wheat,  Bushels  per  Acre 


FIELD 

BROAD- 
BALK 

Hoos 

AGDELL 

AGDELL 

AGDELL 

BROAD- 
BALK 

BROAD- 
BALK 

BROAD- 
BALK 

Crop 
System 

Wheat 
Every 
Year: 
Plots 

Wheat  and 
Fallow 
Alterna- 
ting 

Turnips, 
Barley, 
Fallow, 
Wheat 

Turnips, 
Barley, 
Legume, 
Wheat 

Turnips, 
Barley, 
Legume, 
Wheat 

Wheat 
Every 
Year: 
Plot  2 

Wheat 
Every 
Year: 
Plot  8 

Wheat 
Every 
Year: 
Plot  i  6 

Soil 
Treatment 

None 

None 

None 

None 

Phos- 
phorus 

Farm 
Manure 

Minerals 

and  i  .•() 
Ib.  N 

Minerals 
and  173 
Ib.  N 

1844 

1845 
1846 

1847 
1848 
1849 
1850 
1851 

15.0 

23-3 
18.0 
16.9 
14.8 
19-3 
iS-9 
iS-9 

(fallow) 

(clover) 
30-S 

(clover) 
28.5 

(clover) 
28.0 

20.5 
32.0 

27-3 
29.9 
25.6 
31.0 
28.5 
29.6 

1852 
1853 
1854 
i8S5 
1856 

1857 
1858 
1859 

13-9 
5-9 

21.  1 
17.0 

14-5 
20.0 

18.0 
18.4 

37-o 
(fallow) 
42.0 
17-4 

21.8 

38.0 
25.8 

34-o 

27.6 
19.1 
41.1 
34-6 
36-3 
41-3 
38.8 

36-3 

27-5 
23-5 
48.6 

31-5 
39-1 
48.4 
41.9 

34-5 

28.5 
25-1 
49-9 
32-9 
37-9 
49-4 
41.9 
34-6 

(fallow) 
37-4 

(beans) 
35-3 

(beans) 
35-3 

(fallow) 
35-8 

(beans) 
35-3 

(  beans) 
34-8 

1860 
1861 
1862 
1863 
1864 

12.9 
11.4 

16.0 

J7-3 
16.5 

12.  1 

17.9 

22.9 

32-9 

3'-4 

32-3 
34-9 
38-4 
44.0 
40.0 

3J-3 
3S-i 
39-5 
55-8 
49-9 

32.6 
37-o 
36-3 
55-9 
Si-i 

(fallow) 
45-° 

(beans) 
34-1 

(beans) 
349 

(Note 
Change) 

None 

1865 
1866 
1867 

13-4 

12.  1 
8.9 

24-3 
10.8 
9.6 

37-1 
32.6 

27-5 

43-6 
32.1 

3°-5 

32-4 
17.4 
14.6 

(fallow) 
27.1 

(beans) 

21.0 

(beans) 
19.8 

1868 
1869 
1870 
1871 
1872 

1873 
1874 
1875 

16.6 

'4-3 
15.0 
9-4 
10.8 
n.8 

"•5 
8.6 

25.0 
10.3 
'7-3 
9-3 

12.8 
2.8 
21-5 

16.1 

41.8 
38.3 
36-S 
39-o 
32-4 
26.8 

39-3 
28.9 

46.5 
34-8 

45-3 
27.8 

35-6 
27-5 
40.5 
30.0 

22.8 

16.1 
18.3 
r3-5 
13-1 

12.8 

11.9 

10.  1 

(fallow) 
"•5 

(beans) 
20.  6 

(beans) 
23-9 

(fallow) 
24.4 

(clover) 

21.6 

(clover) 
28.3 

THE    ROTHAMSTED    EXPERIMENTS 


373 


TABLE  62.   WHEAT  YIELDS  AT  ROTHAMSTED  —  (Continued). 
Wheat,  Bushels  per  Acre 


FIELD 

BROAD- 
BALK 

Hoos 

AGO  ELL 

AGDELL 

AGDELL 

BROAD- 
BALK 

BROAD- 

BALK 

BROAD- 
BALK 

Crop 
System 

Wheat 
Everv 
Year": 
Plots 

Wheat  and 
Fallow  Al- 
ternating 

Turnips, 
Barley, 
Fallow, 
Wheat 

Turnips, 
Barley, 
Legume, 
Wheat 

Turnips, 
Barley, 
Legume, 
Wheat 

Wheat 
Every 
Year: 
Plot  2 

Wheat 
Everv 
Year: 
Plots 

Wheat 
Everv 
Year': 
Plot  16 

Soil 
Treatment 

None 

None 

None 

None 

Phos- 
phorus 

Farm 
Manure 

Minerals 
and 
129  Ib.  N 

None 

1876 
1877 
1878 
1879 
1880 
1881 
1882 
1883 

8.1 
8.9 
12.4 
4.8 

"•5 
13-8 

II.O 

'3-9 

10.3 
10.5 
19.8 
6.0 

15-3 

12.3 
n.8 

18.1 

23-9 
24.1 
28.3 
16.0 
38-4 
30-3 
32.8 

35-3 

29.6 
24.8 
38-1 
20.  6 
35-4 
30.8 
37-o 
41.9 

II.O 

9-9 
13.6 
4.9 
14.6 

13-5 
10.8 

iS-9 

(fallow) 

10.  1 

(beans) 
10.4 

(beans) 
14.4 

(fallow) 
33-S 

(clover) 
29.4 

(clover) 
36-5 

(Note 
Changes) 

Minerals 

Minerals 
&  86  Ib.  N 

1884 
1885 
1886 
1887 
1888 
1889 
1890 
1891 

13.0 

JS-3 
9.0 
14.9 

IO.O 

12.3 
14.0 
13-8 

20.3 
23.0 

9-3 
19.0 

12.8 

13.0 

17.8 

23.1 

32-5 
40.1 

36.5 
34-8 
38-0 
40.5 
43-o 
48.5 

43-5 
36.8 

42.4 
34-5 
35-3 
35-5 
37-6 
40.0 

3S-o 
37-9 
44.6 

39-6 
33-9 
29.0 

37-3 

42.1 

(fallow) 
34-8 

(clover) 
25.6 

(clover) 
42.3 

(fallow) 
32.0 

(beans) 
29-5 

(beans) 
42.3 

1892 

1893 
1894 

1895 
1896 
1897 
1898 
1899 

9-4 
9.8 
18.0 

IO.O 

16.8 
8.9 

12.  0 

12.0 

u.8 
J3-5 
15-5 
iS-S 
16.1 
7.0 
20.3 
iS-8 

33-4 
34-3 
45-5 
43-9 
44.0 

37-3 
38.0 

42.5 

38.1 

21.8 

49.0 
40.0 
44.1 

37-o 
29.4 

39-i 

31.8 

19-5 
47.0 
32.6 
37-8 
27-5 
23.8 

37-5 

(fallow)' 

21.8 

(clover) 
23-3 

(clover) 
37-o 

(fallow) 
26.8 

(beans) 
30-3 

(beans) 
40.3 

1900 

IQOI 
I9O2 
1903 
1904 

1905 
1906 
1907 

12-3 
EX.8 

13-3 

7.6 

4.2 

iS.o1 
15.2  i 
9.1 

11.9 
14.7 
22.4 
14.0 

8.2 

12.9 
13-4 
14-3. 

33-3 
39-6 
41-5 
29.7 
22.3 
38-5 
43-6 
33-7 

44-o 
42-4 
45-2 
35-8 
24.9 
40.5 
47-5 
34-7 

34-9 
30-S 
33-5 
26.8 
24.1 
34-2 
43-1 
34-7 

(fallow) 
20.3 

(clover) 
18.9 

(clover) 
28.9 

(fallow) 
16.3 

(clover) 
21.4 

(clover) 
36.8 

1908 

12.4 

7-2 



38.6 

47-5 

38.1 

1  Actual  yield  on  half -plot  after  fallow  (in  making  average,  only  f  of  these  yields 
•are  used). 


374    INVESTIGATION   BY    CULTURE   EXPERIMENTS 

yield  for  the  succeeding  years  is  greater  than  the  average  of  all, 
excluding,  of  course,  the  yields  eliminated. 

The  data  recorded  will  be  especially  useful  for  working  out  as- 
signed problems,  and  it  has  been  brought  together  from  several 
different  publications,  and  the  complete  records  are  made  possible 
only  through  the  kindness  of  Director  Hall  of  Rothamsted,  who 
has  furnished  the  author  with  some  unpublished  data. 

The  last  column  in  Table  62  shows  in  greater  detail  about  the 
same  fact  as  is  well  illustrated  in  the  data  from  the  twin  plots, 
17  and  18,  in  Table  60;  namely,  that  commercial  nitrogen  must  be 
utilized  by  the  crop  for  which  it  is  applied,  or  it  will  be  largely  lost 
in  drainage  water. 

While  plot  16  received  172  pounds  of  nitrogen  in  800  pounds  of 
ammonium  salts  per  annum  for  13  years  (1852  to  1864),  and  pro- 
duced 39.5  bushels  of  wheat  per  acre  as  an  average  for  those  years, 
there  is  apparently  but  little  residual  effect  except  for  one  year 
after  the  application  was  discontinued,  the  average  yields  of  the 
19  years  without  fertilizers  being  14.6  bushels  of  wheat  and  1400 
pounds  of  straw  per  acre. 

The  following  statement  will  be  of  some  interest  in  this  connec- 
tion: 

TABLE  63.  WHEAT  YIELDS  ON  BROADBALK  FIELD,  ROTHAMSTED 
Thirteen  Years'  Average,  1852-1864 


TOTAL 

YIELDS  PER  ACRE 

NITROGEN 

SALTS 

No. 

Son,  TREATMENT  APPLIED  EVERY  YEAR 

PER 

(Lb  ) 

ACRE 

Wheat 

Straw 

(Lb.) 

(Bu.) 

(Lb.) 

5 

Minerals  (P,  K,  Mg,  Na,  S)       .     . 

None 

792 

I8.3 

1862 

6 

Minerals  and  ammonium  salts    .     . 

43 

992 

28.6 

3038 

7 

Minerals  and  ammonium  salts    .     . 

86 

1192 

37-i 

4270 

8 

Minerals  and  ammonium  salts    .     . 

129 

1392 

39-o 

4788 

16 

Minerals  and  ammonium  salts    .     . 

172 

I592 

39-5 

5222 

While  the  second  addition  of  nitrogen  produced  almost  as  large 
an  increase  as  the  first,  the  third  addition  gave  but  little  increase  of 
grain,  and  the  fourth  still  less,  although  the  yield  of  straw  was  very 
appreciably  increased,  even  by  the  fourth  increment  of  nitrogen. 

For  convenience  a  general  summary  of  some  of  the  more  impor- 


THE    ROTHAMSTED    EXPERIMENTS 


375 


tant  data  relating  to  wheat  yields  at  Rothamsted  is  given  in  Table 

64: 

TABLE  64.   WHEAT  YIELDS  AT  ROTHAMSTED 

Wheat,  Bushels  per  Acre,  Averages 


FIELD  

BROAD- 
BALK 

Hoos 

AGDELL 

AGDELL 

AGDELL 

BROAD- 
BALK 

BROAD- 
BALK 

BROAD- 
BALK 

Crop  System    .    . 

Wheat 
Every 
Year: 
Plot3 

Wheat  and 
Fallow 
Alternating 

Turnips, 
Barley, 
Fallow, 
Wheat 

Turnips, 
Barley, 
Legume, 
Wheat 

Turnips, 
Barley, 
Legume, 
Wheat 

Wheat 
Every 
Year: 
Plot  2 

Wheat 
Every 
Year: 
PlotS 

Wheat 
Every 
Year: 
Plot  16 

Soil  Treatment     . 

None 

None 

None 

None 

Phos- 
phorus 

Farm 
Manure 

Minerals 
and 
laplb.  N 

Minerals 
and 
i72lb.N 

rS/i  »     rRer 

17.4 
15-9 

14.8 
15-4 

28.0 
29.6 

35-o 
35-6 

38.3 
38.1 

30.8 

IO44    1051 
1851         .       .       . 

T&ri      Tft^T 

(fallow) 

25-2  ' 
23-5 

3°-5 

28.5 

28.0 

39-5  2 
41.1° 

1855,'  59/63,  '67 

36.3 

3*-4 

31.2 

(Note  Change) 

None 

TCAC    TR8-> 

II.4 
9.2 

J3-7 
12.4 

32.0 
29.8 

34-i 
30.1 

13-3 

II.  I 

1871,  '75,  '79,  '83 

19.9 

20.5 

25-8 

(Note  Changes) 

Minerals 

Minerals 
and 
86  Ib.  N 

iQQ,     TSr>i-i 

12-5 
12.7 

10.4 

8.4 

15-9 
18.4 

14.0 
14.2 

39-6 
42.4 

35-3 
3*-7 

37-8 
38.4 

39-4 

35-3 

34-9 
38.0 

32-7 
30.8 

1887/91/95,  '99 

1900-1907 
1903-1907          . 

28.9 

27.2 

4°-5 

I8.3 

20.  2 

32-9 

1844-1875           . 
1876-1907 

14.8 

"•5 

21.4 
14.7 

30.2 
24-5 

28.1 
23.6 

29-3 
34-8 

33-4 
35-8 

37-5 
36.8 

1844-1907 

J3-1 

17-5 

27.2 

25-7 

32.2 

34-6 

37-i 

1  Average  of  15  crops.        2  Average  of  13  crops  (1852-1864). 
3  Average  of  3  crops  (1855,  '59,  '63). 

In  Table  64,  the  average  wheat  yields  from  the  plots  indicated 
are  grouped  in  two  ways.  First  are  given  the  averages  of  all  years 
for  those  plots  or  twin  plots  (on  Hoos  field)  which  furnish  a  con- 
tinuous record ;  and,  second,  the  averages  are  given  only  for  those 
years  when  wheat  was  grown  on  Agdell  field. 


There  are  a  preliminary  and  a  final  period  of  8  years  each,  and 
three  1 6-year  periods  intervening.  These  figures  show  that  the 
middle  i6-year  period  (1868-1883)  gives  averages  clearly  below  the 
normal,  and  that  the  average  of  the  four  years  within  that  period 
are  still  lower,  thus  proving  that  even  two  1 6-year  periods  may 
not  positively  establish  by  crop  yields  whether  land  is  growing 
better  or  poorer.  A  comparison  of  the  first  and  second  1 6-year 
periods  indicates  that  all  plots  are  growing  poorer;  while  a  com- 
parison of  the  second  and  third  1 6-year  periods  indicates  that  all 
plots  are  growing  better. 

In  the  lower  part  of  Table  64  are  recorded  the  average  yields  for 
all  wheat  crops  grown  in  two  32-year  periods,  and  these  figures  are 
the  best  that  can  be  secured.  They  show  decreases  of  6.7  bushels 
with  the  wheat  and  fallow  plot  (Hoos  field),  5.7  bushels  with  the 
fallow  system,  and  4.5  bushels  with  the  legume  system,  on  Agdell 
field,  and  3.3  bushels  decrease  with  unfertilized  continuous  wheat, 
which,  however,  is  a  greater  percentage  decrease  than  on  either  of 
the  Agdell  plots.  It  should  be  kept  in  mind,  however,  that  wheat 
is  the  only  profitable  crop  now  grown  on  the  unfertilized  Agdell 
plots.  The  yields  increased  slightly  on  the  farm  manure  plot  and 
very  considerably  where  minerals  and  legumes  were  used  on  Agdell 
field. 

Finally,  in  the  last  line,  are  recorded  the  general  average  of  all 
wheat  crops  grown  on  these  plots  since  the  experiments  were  be- 
gun, with  extremes  differing  by  24  bushels,  a  difference  which  in 
64  years  amounts  to  1500  bushels  more  wheat  from  the  applica- 
tion of  plant  food  than  could  be  obtained  without  it,  in  the  same 
system  of  cropping. 

Table  65  gives,  in  brief,  some  of  the  very  interesting  and  valuable 
weather  records  of  Rothamsted,  and  for  comparison  is  given  the 
very  trustworthy  average  rainfall  records  for  northern,  central, 
and  southern  Illinois,  and  Tennessee,  as  representing  a  wide  range 
of  latitude  in  central  United  States,  with  the  average  precipitation 
(including  snow  measured  as  water)  varying  from  33.48  inches  in 
northern  Illinois  to  53.69  in  Tennessee.  (See  also  map  showing 
average  annual  precipitation  in  the  various  parts  of  the  United 
States.) 

The  5<D-year  record  gives  practically  28  inches  as  the  average 


THE    ROTHAMSTED    EXPERIMENTS 


377 


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378    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

annual  rainfall  at  Rothamsted,  and  of  this  amount  50  per  cent  passes 
off  in  drains,  at  a  depth  of  40  inches,  and  50  per  cent  is  evaporated, 
from  a  soil  kept  free  of  vegetation.  Roughly,  the  evaporation  from 
a  bare  soil  may  be  regarded  as  a  constant,  to  be  subtracted  from 
the  rainfall  to  find  the  drainage  (and  run-off,  if  any).  Thus,  if  we 
regard  14.25  inches  as  the  constant  for  evaporation  at  Rothamsted, 
the  drainage  should  be  6.24  inches  for  1898  and  24.44  inches  for 
1903,  while  the  actual  records  show  7.90  and  23.59  inches,  respec- 
tively. 

Of  course  the  evaporation  can  be  markedly  reduced  by  culti- 
vating the  surface  as  soon  as  practicable  after  each  rain,  in  order 
to  destroy  the  capillary  connection  and  to  maintain  a  dust  mulch, 
and  thus  largely  preventing  the  rise  of  moisture  to  the  surface. 
On  the  other  hand,  evaporation  is  greatly  increased  by  growing 
crops,  so  that  during  the  growing  season  the  drainage  would  be 
less  on  the  ordinary  field  than  from  the  bare  soil.1 


BARLEY  EVERY  YEAR  ON  Hoos  FIELD,  ROTHAMSTED 

Table  66  presents  in  summarized  form  the  data  secured  from 
Hoos  field,  where  barley  has  been  grown  every  year  since  1852. 
These  experiments  help  to  answer  some  important  questions  con- 
cerning which  neither  Agdell  nor  Broadbalk  give  any  information. 
The  yields,  as  an  average  of  55  years,  vary  from  14.8  bushels  on 
the  unfertilized  land,  and  15.7  bushels  where  only  the  sulfates 
of  potassium,  magnesium,  and  sodium  were  used,  to  43.9  bushels 
with  sodium  nitrate  and  acid  phosphate,  and  47.7  bushels  with 
farm  manure  (15.7  tons  a  year). 

As  an  average  of  the  3<D-year  and  25-year  periods,  the  yields 
have  decreased  nearly  10  bushels  per  acre  on  all  plots  receiving 
nitrogen,  undoubtedly  because  the  43  pounds  of  nitrogen  was  not 
sufficient  for  larger  crops,  after  deducting  losses  by  leaching.  It 
will  be  remembered  that  the  second  addition  of  43  pounds  of  nitro- 

1  Ingle  reports  some  computations  in  his  "Manual  of  Agricultural  Chemistry," 
page  76,  in  which  the  drainage  is  reckoned  at  about  86  inches;  but  probably  the 
intention  was  to  use  8.6  inches,  which  would  reduce  his  estimated  "enormous  loss 
of  phosphoric  acid"  to  a  very  insignificant  amount  quite  in  harmony  with  other 
data,  such  as  he  gives  on  page  77. 


THE    ROTHAMSTED    EXPERIMENTS  379 

gen  on  Broadbalk  produced  9.0  bushels  of  wheat  per  acre.  A  40- 
bushel  crop  of  barley  would  remove  in  the  grain  and  straw  about 
56  pounds  of  nitrogen,  in  accordance  with  the  average  of  many 
analyses;  so  that,  where  4o-bushel  crops  are  produced  with  only 
43  pounds  of  nitrogen  supplied,  the  soil  is  now  being  exhausted  of 
its  nitrogen  content  about  as  rapidly  as  on  the  unfertilized  landl 
According  to  the  analyses  reported  by  Dyer,  the  nitrogen  content 
of  the  soil  to  a  depth  of  27  inches  decreased  by  528  pounds  per  acre 
on  plot  A4  and  by  841  pounds  on  plot  N4  during  the  14  years  from 
1868  to  1882,  while  the  nitrogen  content  of  plot  04  actually  in- 
creased by  8 1  pounds  per  acre. 

This  problem  is  complicated  by  the  fact  that  there  is  often  con- 
siderable growth  of  leguminous  weeds  (especially  of  yellow  trefoil) 
on  plot  04.  The  decrease  in  yield  from  24.2  to  15.5  bushels  cer- 
tainly does  not  harmonize  with  any  actual  increase  in  the  nitrogen 
content  of  plot  04,  but  it  seems  very  certain  that  the  nitrogen 
content  of  plots  A4  and  N4  was  drawn  upon  during  the  14  years 
at  the  rate  of  40  to  50  pounds  a  year,  of  which  probably  one  half 
is  lost  in  drainage,  as  an  average. 

In  the  lower  part  of  Table  66  are  recorded  some  computed  effects 
for  different  elements  under  different  conditions.  Of  course,  many 
other  similar  computations  could  be  made  from  the  data.  In 
computations  of  this  sort,  the  first  effect  should  be  determined  for 
the  most  limiting  element,  the  next  effect  for  the  second  limiting 
element,  etc.  While  it  is  of  interest  to  compute  the  effect  of  apply- 
ing the  most  limiting  element  where  all  others  have  been  applied, 
the  result  has  no  practical  significance,  because  every  application 
should  pay  for  itself. 

It  is  evident  that  nitrogen  is  the  most  limiting  element  for  barley 
on  Hoos  field,  because  the  ammonium  salts  produce  a  greater  in- 
crease alone  than  either  acid  phosphate  or  alkali  salts.  Phosphorus 
is  as  clearly  the  second  limiting  element. 

While  the  alkali  salts  alone  had  some  power  to  increase  the  yields 
during  the  earlier  years  (probably  due  to  their  power  to  liberate 
phosphorus  or  encourage  nitrification),  their  stimulating  action 
during  those  years  is  indicated  by  reduced  yields  during  the  later 
25-year  period  when  plot  03  produced  less  than  Oi.  Exactly  the 
same  conditions  appear  where  alkali  salts  have  been  added  to  acid 


380    INVESTIGATION   BY   CULTURE   EXPERIMENTS 


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382     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

phosphate  (compare  O2  and  04  for  the  3o-year  and  25-year 
periods). 

Where  nitrogen  has  been  applied  without  phosphorus,  the  stimu- 
lating effects  of  the  alkali  salts  is  still  apparent,  probably  because 
they  continue  to  liberate  some  phosphorus  from  the  soil.  Where 
both  nitrogen  and  phosphorus  are  provided,  the  effect  of  the  al- 
kali salts  is  most  marked,  and  here  it  is  increasing,  very  possibly 
because  all  of  the  potassium  needed  by  the  larger  crops  is  not  liber- 
ated from  the  soil  on  account  of  lack  of  decaying  organic  matter. 
Here  it  will  be  seen,  however,  that  the  sodium  in  sodium  nitrate 
without  potassium  (plot  N2)  produces  even  better  results  than  the 
alkali  salts,  including  potassium  (plots  A4  and  N4),  but  this  com- 
parison is  complicated  by  the  fact  that  ammonia  nitrogen  and 
nitrate  nitrogen  may  have  different  effects,  and  the  chlorin  and 
sulfate  radicle  may  also  produce  some  effect. 

It  is  of  special  interest  to  compare  the  marked  residual  effect  of 
farm  manure  on  plot  7-1,  Hoos  field,  with  the  absence  of  such  an 
effect  from  the  heavy  applications  of  commercial  fertilizers  (in- 
cluding 172  pounds  of  nitrogen)  on  plot  16  of  Broadbalk  field.  (See 
Table  62.)  However,  it  should  be  kept  in  mind  that  plot  7-1  re- 
ceived 314  tons  of  manure  during  the  20  years  (1852  to  1871), 
which  is  equivalent  to  almost  6  tons  per  acre  a  year  for  the  entire 

55  years- 

At  40  cents  a  bushel  for  barley,  the  manure  applied  to  plot  7-2 
has  been  worth  about  85  cents  a  ton,  while  that  applied  to  plot  7-1 
has  already  paid  $1.36  a  ton  for  itself,  not  deducting  interest  on 
investment  or  counting  the  remaining  residual  effect,  plot  Ci  being 
used  as  the  basis  for  comparison. 

A  comparison  of  plots  N2  and  7-2  shows  the  marked  superiority 
of  the  farm  manure  in  a  dry  season  (1893),  while  the  commercial 
fertilizers  give  nearly  as  good  results  in  normal  or  wet  seasons,  and 
probably  would  surpass  the  farm  manure  if  the  nitrogen  were  in- 
creased sufficiently. 

If  the  43  pounds  of  nitrogen  cost  $6.45  and  the  29  pounds  of 
phosphorus  $3.48,  and  if  barley  is  worth  40  cents  a  bushel,  the 
ammonia  nitrogen  has  left  a  deficit  of  $1.97  a  year  for  the  55  years, 
while  phosphorus,  in  addition  to  nitrogen,  has  overcome  $1.92  of 
the  deficit,  leaving  a  net  loss  of  5  cents  per  acre  per  annum. 


THE    ROTHAMSTED    EXPERIMENTS  383 

The  nitrate  nitrogen  practically  paid  for  itself  as  an  average  of 
the  first  30  years,  but  left  a  deficit  of  about  $i  a  year  for  the 
subsequent  25-year  period,  of  which,  moreover,  the  last  15  years 
show  an  annual  loss  of  $1.49. 

Phosphorus  added  to  nitrate  has  paid  for  itself  and  60  per  cent 
net  profit  as  an  average  of  the  55  years,  and  the  effect  of  phosphorus 
is  apparently  increasing  where  applied  in  this  connection,  which 
practically  amounts  to  using  it  in  addition  to  both  nitrogen  and 
potassium,  assuming  that  the  sodium  has  power  to  liberate  potas- 
sium from  the  soil.  If  the  nitrogen  were  secured  from  the  air  by 
clover,  and  if  the  potassium  were  liberated  from  the  soil  also  by 
clover,  plowed  under  directly  or  in  manure,  it  is  easy  to  see  that 
applied  phosphorus  would  be  still  more  profitable,  especially  if 
the  29  pounds  were  applied  in  raw  natural  phosphate  at  a  cost  of 
87  cents  instead  of  in  acid  phosphate  costing  $3.48. 

It  should  be  remembered  always  that  computations  based  upon 
increases  compared  with  the  yields  from  unfertilized  land  may 
indicate  profits  that  would  not  be  wholly  realized  if  the  total  yield 
of  the  unfertilized  land  is  not  sufficient  to  pay  for  its  own  cost. 
In  other  words,  if  it  costs  more  than  the  value  of  14.8  bushels  of 
barley  to  secure  that  yield,  then  the  financial  deficit  from  the  un- 
fertilized land  must  also  be  overcome  before  any  profit  can  be  had 
from  the  use  of  fertilizers. 

Furthermore,  in  planning  systems  of  permanent  agriculture,  we 
must  also  consider  whether  the  apparent  increasing  gains  are  due 
solely  to  improvement  resulting  from  soil  treatment,  or  in  part  to 
the  general  depletion  of  the  unfertilized  land.  Probably  nothing 
is  more  difficult  for  the  average  landowner  to  realize  than  that 
what  appears  to  be  profit  is  in  part  at  least  taken  from  his  own 
capital.  This  is  very  clearly  illustrated  in  the  Hoos  barley  experi- 
ments. Thus,  with  nitrogen  on  plot  Ai,  during  the  15  years  (1892 
to  1906),  there  appears  to  be  an  average  increase  in  yield  of  nearly 
8  bushels  per  acre  above  the  unfertilized  yield;  but,  by  referring 
to  the  average  for  the  first  10  years  (1852  to  1861),  it  will  be  seen 
that  the  unfertilized  yield  has  decreased  by  more  than  12  bushels. 
On  this  basis,  as  an  average  of  the  last  25  years,  the  apparent  in- 
crease from  nitrogen  is  wholly  represented  in  the  decrease  in  pro- 
ductive power,  and  consequently  in  the  decrease  in  value,  of  the 
unfertilized  land. 


384    INVESTIGATION   BY    CULTURE    EXPERIMENTS 

POTATOES  EVERY  YEAR  ON  Hoos  FIELD,  ROTHAMSTED 

On  another  part  of  Hoos  field  potatoes  were  grown  every  year 
for  26  years  (1876-1901).  There  were  several  changes  in  the  va- 
rieties grown,  so  that  but  little  importance,  at  most,  should  be 
attached  to  the  yields  in  successive  periods  as  indicating  decreas- 
ing or  increasing  fertility,  except  in  those  cases  where  the  change 
is  so  regular  and  so  marked  as  to  leave  no  room  for  doubt.  It  is 
especially  to  be  kept  in  mind  that  the  variety  "  White  Beauty  of 
Hebron  "  was  grown  only  during  the  last  five  years  (1897-1901). 
During  the  previous  21  years  the  varieties  grown  were  "  Rock  " 
for  4  years,  "Champion  "  for  n  years,  "  Button's  Abundance  " 
for  5  years,  and  "  Bruce"  for  one  year,  and,  in  this  order,  from 
1876  to  1896.  Thus,  the  two  five-year  periods  from  1882  to  1891 
should  be  comparable,  but,  of  course,  seasonal  variation  renders 
even  that  possible  comparison  of  doubtful  value. 

The  special  object  of  the  experiment  was  to  ascertain  the  effect 
upon  the  yield  of  potatoes  of  different  fertilizing  materials,  as  indi- 
cated in  Table  68,  which  shows  the  general  plan,  the  treatment 
applied,  and  the  yields  obtained  each  year. 

One  of  the  points  most  clearly  indicated  by  the  data  in  Table  68 
is  that  "  White  Beauty  of  Hebron,"  grown  from  1897  to  1901, 
was  a  very  poor  yielding  variety. 

It  may  be  said  that  1879  was  an  exceedingly  wet  year  at  Rotham- 
sted,  the  rainfall  being  2.79,  3.48,  5.55,  4.24,  and  6.56  inches  for 
the  respective  months  April  to  August. 

In  any  consideration  of  these  potato  experiments,  it  should  be 
kept  in  mind  that  potatoes  are  a  market-garden  crop,  and  constitute 
one  form  of  intensive  agriculture.  An  annual  investment  of  $25 
to  $40  an  acre  for  fertilizing  materials  is  not  beyond  consideration 
for  a  crop  that  may  yield  300  bushels,  that  may  be  worth  $150 
an  acre. 

In  the  last  lines  of  Table  68  are  given  the  average  yields  for  the 
first  6-year  period  and  for  the  four  successive  5-year  periods,  and, 
finally,  the  average  for  the  26-year  period,  followed  by  the  several 
averages  for  the  value  of  the  increase  and  the  cost  of  treatment. 

Since  New  York  leads  in  the  production  of  potatoes,  the  price 


THE    ROTHAMSTED    EXPERIMENTS  385 

used  in  these  computations  is  50  cents  a  bushel  (57.6  cents  being 
the  10- year  average  farm  price  for  New  York  State,  and  also  for 
Ohio),  and  the  cost  of  manure  is  figured  at  $2  a  ton;  but  these 
figures  should  always  be  modified  to  meet  average  local  conditions. 
They  only  help  to  summarize  the  results  so  as  to  bring  to  mind 
their  economic  importance. 

Thus,  at  the  prices  named,  the  treatment  applied  to  plot  4  has 
cost  $35.32  a  year,  and  the  increase  produced  has  been  worth  $70 
a  year,  or  sufficient  to  pay  the  cost  and  leave  practically  100  per 
cent  net  profit. 

The  ammonium  salts  on  plot  5  have  paid  but  half  their  cost,  and 
the  sodium  nitrate  alone  has  but  slightly  more  than  paid  for  itself. 
By  far  the  largest  returns  for  money  invested  has  been  from  acid 
phosphate  on  plot  9,  which  has  paid  for  itself  and  added  more  than 
600  per  cent  net  profit  as  an  average  of  the  26  years.  Indeed,  the 
acid  phosphate  alone  exactly  doubled  the  average  yield  of  26  years. 

The  alkali  minerals,  including  300  pounds  of  potassium  sulfate, 
ico  pounds  of  magnesium  sulfate  (Epsom  salt),  and  100  pounds  of 
sodium  sulfate  (Glauber  salt) ,  have  not  paid  their  cost  when  used 
in  addition  to  acid  phosphate,  the  average  annual  increase  of  plot 
10  over  plot  9  being  only  7  bushels,  and  the  annual  cost  $7.90. 

The  largest  average  yield  and  the  largest  net  profit  per  acre  is 
from  plot  8,  which  produces  as  much  on  one  acre  as  were  grown  on 
four  acres  of  untreated  land.  It  should  be  noticed,  however,  that, 
during  the  last  10  years  of  the  experiment,  the  farm  manure  plots, 
3  and  4,  have  forged  ahead  of  the  complete  chemical  fertilizers  on 
plots  7  and  8. 

Director  Hall  makes  the  following  statements  in  his  book  on 
"  Rothamsted  Experiments  "  (1905) : 

"In  the  Hoos  field,  experiments  upon  potatoes  were  begun  in  1876,  and  con- 
tinued for  twenty -six  years ;  they  were  then  discontinued,  because  the  crop  on 
the  plots  receiving  no  organic  manures  had  fallen  to  a  very  low  ebb  in  conse- 
quence of  the  deterioration  of  the  texture  of  the  soil.  But  on  the  plots  receiving 
farmyard  manure,  and  even  on  those  receiving  only  a  complete  artificial  manure 
(plots  7  and  8),  the  crop  was  maintained  in  favorable  seasons.  No  falling  off 
was  observed  which  could  be  attributed  to  the  land  having  become  'sick' 
through  the  continuous  growth  of  the  same  crop,  or  through  the  accumulation 
of  disease  in  the  soil." 


386    INVESTIGATION   BY    CULTURE    EXPERIMENTS 


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THE   ROTHAMSTED    EXPERIMENTS 


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388    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

It  should  be  noted  that  the  average  yields  on  plots  3,  4,  and  8 
increased  during  the  fifteen  years  previous  to  the  last  five,  when  the 
"  Beauty  of  Hebron  "  variety  was  introduced;  and,  as  an  average, 
the  farm-manure  plots  yielded  higher  during  the  five  years  ending 
1896,  than  during  the  six  years  beginning  1876,  notwithstanding 
the  addition  of  acid  phosphate  during  the  earlier  period. 

During  the  first  six  years  the  use  of  $150  worth  of  plant  food  on 
plot  8  produced  $615  worth  of  potatoes,  above  the  85-bushel  yield 
on  the  untreated  land,  which  is  also  the  lo-year  average  yield  of 
potatoes  for  New  York  State.  Even  when  used  in  addition  to 
manure,  during  the  first  six  years,  acid  phosphate,  as  well  as  phos- 
phate and  nitrate,  paid  100  per  cent  net  profit  on  the  investment; 
but  no  test  was  made  with  manure  and  nitrate  without  phosphate. 

These  Rothamsted  data  furnish  no  information  concerning  the 
effect  of  potassium,  except  that  it  failed  to  pay  its  cost  on  plot  10. 
It  might  be  said  that  all  but  9  bushels  of  the  i96-bushel  increase  on 
.plot  7  should  be  credited  to  the  minerals  (compare  plot  5),  but  how 
much  of  this  increase  would  have  been  produced  by  acid  phosphate 
and  ammonium  salts  is  not  revealed;  on  the  other  hand,  nitrogen 
must  be  credited  with  the  increase  from  plot  7  above  plot  10;  all 
of  which  means  that  phosphorus  is  the  first  limiting  element  and 
nitrogen  the  second,  for  the  growth  of  potatoes  on  this  normal  soil. 

To  maintain  satisfactory  soil  texture  and  to  provide  for  the 
liberation  of  potassium,  magnesium,  etc.,  from  the  immense  supply 
in  the  soil,  liberal  applications  of  manure  should  be  made,  and  for 
the  improvement  of  the  subsoil  the  growing  of  clover  in  rotation  will 
produce  benefits  that  manure  cannot  produce.  On  the  other  hand, 
in  such  intensive  agriculture,  there  is  large  profit  in  a  moderate 
use  of  commercial  nitrogen,  especially  in  such  form  as  sodium 
nitrate,  which  also  furnishes  sodium  as  a  soil  stimulant. 

Whether  one  should  use  raw  phosphate  or  acid  phosphate,  in 
connection  with  the  manure,  clover,  and  sodium  nitrate,  is  not 
established,  but  the  Rhode  Island  and  Wisconsin  data  indicate  that 
potatoes  are  able  to  utilize  the  raw  phosphate  to  some  extent,  and 
(in  Rhode  Island)  even  without  adequate  provision  for  decaying 
organic  matter.  It  would  seem  advisable,  however,  to  use  the  acid 
phosphate  until  the  raw  rock  has  been  more  thoroughly  tested  for 
potatoes,  especially  considering  that  the  expense  for  phosphorus, 


THE   ROTHAMSTED   EXPERIMENTS  389 

even  in  acid  phosphate,  is  one  of  the  smallest  items  in  the  produc- 
tion of  this  expensive  and  valuable  crop. 

RESIDUAL  EFFECT  OF  FERTILIZERS  ON  Hoos  FIELD 

Any  one  who  has  made  himself  acquainted  with  the  26-year 
potato  experiments  on  Hoos  field  will  naturally  be  interested  in  the 
further  history  of  those  plots.  The  data  reported  since  1901  are 
given  in  Table  69,  following  a  summary  of  the  soil  treatment  and 
potato  yields. 

The  barley  yields  for  1902  are  in  harmony  with  the  common  ex- 
perience that  potatoes  leave  an  excellent  seed  bed  for  a  succeeding 
crop  of  barley  or  wheat;  and  the  residual  effect  for  one  year  is  also 
very  marked  where  nitrogen  has  been  applied,  as  was  the  case  with 
continuous  wheat  on  plot  16  of  Broadbalk  field.  Even  the  first 
barley  crop  on  plots  9  and  10  are  no  better  than  on  plots  i  and  2, 
clearly  showing  that  nitrogen  was  the  limiting  element  for  the  quick- 
growing  barley  crop.  Aside  from  the  farm-manure  plots,  much 
less  residual  effect  is  apparent  after  1902;  and,  in  all  cases  where 
the  treatment  is  comparable,  the  barley  yields  of  these  plots  in 
1903  were  less  than  on  corresponding  plots  in  the  same  field  (Hoos) 
where  barley  had  been  grown  every  year  for  more  than  half  a 
century. 

If  we  keep  in  mind  that  nine  of  the  eighteen  plots  of  continuous 
barley  produced  more  than  36  bushels  per  acre  in  1902,  also  that 
four  of  the  ten  plots  where  potatoes  had  been  grown  for  26  years 
produced  less  than  36  bushels  of  barley  in  1902,  and  that  the 
largest  average  yield  of  potatoes  from  the  farm-manure  plots  (3 
and  4),  either  for  one  year  or  for  five  years,  was  secured  after  pota- 
toes had  been  grown  on  the  same  land  every  year  for  more  than 
fifteen  years,  then  the  following  statement  by  Whitney  seems 
clearly  inapplicable: 

"One  of  the  most  interesting  instances  going  to  show  that  toxic  substances 
are  formed  and  that  what  is  poisonous  to  one  crop  is  not  necessarily  poisonous 
or  injurious  to  another  is  a  series  of  experiments  of  Lawes  and  Gilbert  —  the 
growing  of  potates  for  about  fifteen  years  on  the  same  field.  At  the  end  of 
this  period  they  got  the  soil  into  a  condition  in  which  it  would  not  grow  potatoes 
at  all.  The  soil  was  exhausted,  and  under  the  older  ideas  it  was  necessarily 
deficient  in  some  plant  food.  It  seems  strang?  that,  under  our  old  ideas 


390    INVESTIGATION   BY   CULTURE   EXPERIMENTS 


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THE   ROTHAMSTED    EXPERIMENTS  391 

of  soil  fertility,  if  the  soil  became  exhausted  for  potatoes,  it  should  grow  any 
other  crop,  because  the  usual  analysis  shows  the  same  constituents  present  in  all 
of  our  plants,  not  in  the  same  proportion,  but  all  are  present  and  all  necessary, 
so  far  as  we  know.  This  field  was  planted  in  barley,  and  on  this  experimental 
plot  that  had  ceased  to  grow  potatoes  they  got  75  bushels  of  barley."  l 

While  the  avoidance  of  possible  injury  to  plants  from  the  pos- 
sible toxic  substances  that  may  possibly  be  excreted  from  the  roots 
of  the  same  kind  of  plants  is  by  no  means  precluded  from  among 
the  possible  benefits  of  crop  rotation,  the  Rothamsted  data  fur- 
nish little  evidence  in  favor  of  such  a  theory,  and  even  less  in  sup- 
port of  the  Whitney  theory,  that  crop  rotation  alone  will  maintain 
the  fertility  of  the  soil.  On  the  other  hand,  the  residual  effect  of 
the  farm  manure  applied  to  plot  3  (Table  69),  previous  to  1882, 
is  still  apparent  after  the  removal  of  twenty-five  crops,  in  com- 
parison with  the  unfertilized  land. 

Clover  was  seeded  in  1905  on  plots  6,  8,  and  10,  and  cowpeas  on 
plots  5,  7,  and  9.  The  cowpeas  failed,  and  in  1906  clover  was  seeded 
on  5,  7,  and  9.  The  clover  yields  thus  far  reported  are  recorded 
in  Table  69.  They  are  of  some  interest  for  comparison  with  the 
1906  clover  on  Agdell  field  (Table  56),  where  clover  "  sickness  "  has 
been  recognized  by  the  Rothamsted  Station  as  the  probable  cause 
of  frequent  failure  during  more  than  half  a  century.  There  is  much 
evidence  to  show  that  soils  frequently  become  "  sick  "  from  the 
continuous  growing  of  flax  and  of  certain  legume  crops.  "  Clover 
sick  "  land  and  "  bean  sick  "  land  are  expressions  common  to 
nearly  all  countries.  Cowpea  wilt  and  flax  wilt  are  well  understood 
fungous  diseases,  and  the  evidence  thus  far  secured  indicates  that 
clover  "  sickness  "  is  also  due  to  a  fungus  rather  than  to  any  pos- 
sible toxic  excreta.  (See  below.) 

HAY  EVERY  YEAR  FROM  PERMANENT  MEADOW  AT  ROTHAMSTED 

In  1856,  experiments  were  begun  at  Rothamsted  in  top-dressing 
meadow  land  with  various  fertilizing  materials,  as  indicated  in 

1  From  page  14  of  Farmers'  Bulletin  257,  U.  S.  Department  of  Agriculture. 
The  careful  student  is  advised  to  secure  a  copy  of  this  interesting  bulletin  and 
also  Bulletins  22  and  55  of  the  U.  S.  Bureau  of  Soils  in  which  are  set  forth  in  greater 
detail  the  unique  theories  of  Whitney  and  Cameron  concerning  soil  fertility.  They 
should  be  read  in  connection  with  Circulars  72,  105, 123,  124,  and  129,  of  the  Uni- 
versity of  Illinois  Agricultural  Experiment  Station. 


39* 


INVESTIGATION   BY   CULTURE   EXPERIMENTS 


Table  70.  The  land  was  known  to  have  been  used  for  meadow  and 
pasture  for  at  least  two  centuries  previous  to  the  beginning  of  these 
experiments. 

The  field  was  known  as  The  Park,  and  consisted  of  normal,  nearly 
level  upland  soil,  very  similar  to  Agdell,  Broadbalk,  Hoos,  and 
other  Rothamsted  fields,  except  that  The  Park  had  not  been  heav- 
ily chalked  in  the  earlier  years,  while  the  other  Rothamsted  fields 
(with  the  exception  of  Geescroft  at  least)  had  received  chalk  dress- 
ings probably  amounting  to  100  tons  or  more  of  calcium  carbonate 
per  acre. 

The  Rothamsted  Station  has  no  knowledge  of  any  grass  seed 
ever  having  been  sown  on  The  Park,  either  before  or  since  the 
beginning  of  the  experiments.  From  1856  to  1874  only  the  first 
crops  were  harvested  and  weighed  as  hay,  the  second  crops  having 
been  fed  off  by  sheep,  as  a  rule,  and  the  sheep  having  been  con- 
fined upon  the  plots  so  that  the  droppings  were  returned  to  the 
respective  plots.  Since  1874,  the  second  crops,  when  sufficient  in 
amount  to  justify  it,  have  also  been  harvested  and  removed  as  hay. 

On  a  few  plots  the  treatment  was  not  fully  decided  upon  until  a 
few  years  after  the  beginning  of  the  experiments.  Thus,  plot  u 
was  divided  in  1862,  when  the  addition  of  sodium  silicate  was 
begun  on  11-2.  At  the  same  time  the  application  of  potassium  was 
discontinued  on  plots  8  and  10  and  the  sodium  sulfate  changed  from 
200  pounds  to  500  pounds  for  1862  and  1863  and  then  to  250 
pounds.  The  periods  represented  in  the  first  column  of  averages 
vary  from  7  to  10  years. 

In  studying  the  results  from  Table  70,  it  should  be  kept  in  mind 
that  all  applications  have  been  made  only  as  top-dressings;  and, 
consequently,  that  benefit  could  be  expected  only  from  those 
materials  which  were  sufficiently  soluble  to  permit  of  their  being 
carried  into  the  soil  to  the  depth  where  the  plant  roots  secure 
considerable  amounts  of  their  food  supplies.  It  should  be  kept  in 

NOTES  TO  TABLE  70.  The  "minerals"  regularly  included  392  Ib.  of  acid 
phosphate  (400  Ib.  of  basic  slag,  1897  to  I9°2),  500  Ib.  of  potassium  sulfate  (300  Ib. 
for  1878  and  previously),  100  Ib.  of  magnesium  sulfate,  and  100  Ib.  of  sodium 
sulfate  (200  Ib.,  1856  to  1863),  but  where  potassium  was  omitted  (plots  8  and  10), 
the  sodium  sulfate  was  increased  to  250  Ib.  from  1864  to  1904.  The  farm  manure 
applied  to  plots  i  and  2  was  at  the  rate  of  15.7  tons  per  acre  for  the  eight  years, 
1856  to  1863. 


THE   ROTHAMSTED    EXPERIMENTS 


393 


PER  CENT  BY  WEIGHT 
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Son.  TREATMENT  APPLIED  PER  ACRE 
EVERY  YEAR 
(Excepting  Changes  as  Noted) 

S 

(Manure,  amm.  salts);  then  amm.  sa 
(Manure);  then  unfertilized  .  . 
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(Minerals);  then  minerals,  except  K 

Amm.  salts  and  minerals  .  .  . 
Amm.  salts  and  minerals,  except  K 
Amm.  salts  and  minerals  .  . 
Amm.  salts,  minerals,  and  silicate2 

Unfertilized  
Amm.  salts,  minerals,  and  straw3 
Nitrate  and  minerals  .... 

(Nitrate);  then  minerals  .  .  . 
Nitrate  and  minerals  .... 
Sodium  nitrate  

& 

^°  i,  i, 

394     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

mind,  also,  that  soluble  acid  phosphate  is  almost  immediately 
converted  -into  an  insoluble  form  when  brought  in  contact  with 
ordinary  soil,  and  that  alkali  salts  have  more  or  less  power  to  make 
phosphates  soluble. 

The  yields  harvested  for  the  first  and  second  lo-year  periods 
are  comparable  for  most  plots,  and  this  is  also  true  for  the  following 
2o-year  and  lo-year  periods;  although  the  yields  of  first  crops 
only  (1856  to  1875)  cannot  be  compared  with  the  yields  of  two 
cuttings  (1876  to  1905).  The  double  comparisons  plainly  indicate 
that  the  yield  of  hay  is  decreasing  on  all  plots  except  those  to  which 
minerals  are  applied  without  nitrogen  (plots  5,  6, 7,  and  15)  orwith 
organic  matter  (plot  13).  The  largest  percentage  decrease  during 
the  last  thirty  years  has  occurred  on  the  unfertilized  land  (plots 
2,  3,  and  12)  and  on  plot  i,  where  ammonium  salts  and  heavy 
applications  of  farm  manure  were  used  during  the  eight  years, 
1856  to  1863,  and  ammonium  salts  alone  thereafter.  Marked 
decreases  have  also  followed  the  use  of  acid  phosphate  and  ammo- 
nium salts,  either  separately  or  together;  while  the  addition  of 
alkali  salts  with  both  nitrogen  and  phosphorus  has  lessened  the 
decrease,  but  not  entirely  prevented  it. 

Plots  6  and  7  appear  to  have  reached  an  equilibrium,  having 
produced  about  the  same  yield  during  the  last  lo-year  period  as 
during  the  previous  2o-year  period,  and  plot  15  appears  to  be  in 
the  same  class  during  the  last  zo-year  period. 

A  most  striking  fact  is  the  controlling  influence  of  the  alkali 
salts;  but  there  is  no  plot  receiving  alkali  salts  alone,  and  the 
question  again  arises  whether  the  effect  of  the  alkali  salts  is  more 
largely  direct  or  indirect.  Here,  as  on  the  Broadbalk  field,  the  mag- 
nesium and  sodium  salts  have  produced  a  marked  effect,  as  will  be 
seen  from  plots  8  and  10  in  comparison  with  plots  4-1  and  4-2. . 
Thus,  as  an  average  of  the  thirty  years,  1876  to  1905,  the  addition 
of  250  pounds  of  sodium  sulfate  and  100  pounds  of  magnesium  sul- 
fate  increased  the  yield  of  plot  10  over  that  of  plot  4-2  by  1243 
pounds  of  hay  per  acre  per  annum;  but  increasing  the  application 
of  alkali  salts  from  350  pounds  to  700  pounds,  by  substituting  500 
pounds  of  potassium  sulfate  for  150  pounds  of  the  sodium  sulfate, 
produced  a  further  increase  of  only  1009  pounds  of  hay  on  plot  9; 
while  the  further  addition  of  400  pounds  of  sodium  silicate  on  plot 


THE   ROTHAMSTED   EXPERIMENTS  395 

1 1-2  produced  an  increase  of  845  pounds  of  hay  over  plot  n-i, 
as  a  3<D-year  average.  When  we  remember  that  the  sulfates  of  mag- 
nesium and  sodium  contain  large  amounts  of  water  of  crystalliza- 
tion, and  that  potassium  sulfate  is  an  anhydrous  salt,  the  value  of 
potassium  for  its  own  sake  is  still  more  questionable. 

Attention  is  called  to  the  fact  that  the  total  weight  of  salts 
applied  to  the  best-yielding  plot  (11-2)  is  greater  than  the  total 
weight  of  field-cured  hay  produced  on  the  unfertilized  land,  as  an 
average  of  the  last  lo-year  period. 

It  seems  very  probable  that  the  benefit  of  the  alkali  salts  is  due 
in  part  at  least  to  their  power  to  increase  or  maintain  the  solu- 
bility of  the  phosphorus,  and  thus  provide  a  means  by  which  that 
element  is  carried  deeper  into  the  soil,  where  it  may  be  taken  up 
by  the  plant  roots.  Even  then  it  is  probable  that  a  very  consider- 
able part  of  the  phosphorus  applied  to  The  Park  plots  during  the 
past  half -century  still  remains  within  an  inch  or  two  of  the  surface. 

The  botanical  composition  of  the  herbage  (first  crops  only)  is 
given  in  the  last  four  columns  of  Table  70;  first  for  the  average  of 
nearly  fifty  years,  and  second  for  the  season  of  1902.  It  is  espe- 
cially interesting  to  note  the  large  percentages  of  legumes  on  plots 
6,  7,  and  15,  which  receive  the  minerals  alone  and  consequently 
must  depend  upon  legumes  for  a  supply  of  nitrogen.  Plot  8  (miner- 
als, except  potassium)  shows  the  next  highest  percentage  of  leg- 
umes "in  1902;  and,  in  proportion  to  the  actual  application  of 
anhydrous  alkali  salts,  this  is  relatively  higher  than  the  figures 
indicate. 

Plot  1 6,  which  receives  the  minerals  and  the  smaller  application 
of  nitrate,  shows  about  the  same  percentage  of  legumes  as  the 
unfertilized  plots  and  the  acid-phosphate  plot.  Where  heavy 
applications  of  nitrogen  are  used,  the  legumes  are  almost  lacking, 
and  entirely  so  in  a  few  cases. 

On  some  plots  the  herbage  is  largely  weeds.  Thus,  the  1902  crop 
of  plot  2  ,  (unfertilized  since  1864)  consisted  of  30  per  cent  of 
grasses  and  legumes  and  70  per  cent  of  weeds,  so  that  the  produce 
is  deteriorating  in  quality  as  well  as  in  yield.  The  following  state- 
ment by  Lawes  and  Gilbert  was  published  in  1900: 

"The  total  number  of  species  that  have  been  observed  on  the  plots  is  89,  com- 
prised in  63  genera,  and  22  orders ;  whilst,  to  take  some  of  the  more  important 


396    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

orders,  there  have  been  found  —  of  Gramineae  (grasses)  20  species,  of  5  genera; 
of  Leguminosae  10  species,  of  5  genera;  of  Compositas  13  species,  of  12  genera; 
of  Umbelliferae  5  species,  of  5  genera;  of  Polygonacese  3  species,  of  i  genus; 
of  Ranunculacese  5  species,  of  i  genus;  and  of  Plantaginaceae  2  species,  of  i 
genus.  The  majority  of  the  22  orders  are,  however,  represented  by  only  one, 
two,  or  three  species,  and  only  one  genus  each.  To  take  an  example,  it  may 
be  stated  that  the  herbage  of  the  unmanured  plot  comprises  about  50  species, 
and  that  any  kind  of  manure  —  that  is,  anything  that  increases  the  growth  of 
any  species  —  induces  a  struggle,  greater  or  less  in  degree,  causing  a  greater 
or  less  diminution,  or  a  disappearance,  of  some  other  species;  until  on  some 
plots,  and  in  some  seasons,  not  more  than  15  species  have  been  observable; 
indeed,  on  some,  after  a  number  of  years,  no  more  than  this  are  ever  traceable." 

Director  Hall  reports  that  in  1903  about  97  per  cent  of  the  prod- 
uce from  plot  n-i  (ammonium  salts  and  minerals)  consisted  of 
three  species:  false  oat  grass  (Arrhenatherum  avenaceum), 
meadow  foxtail  (Alopecurus  pratensis),  and  meadow  soft  grass 
(Holcus  lanatus}.  On  plot  14,  which  receives  nitrate  and  minerals, 
the  herbage  is  quite  similar  except  that  about  45  per  cent  of  meadow 
soft  grass  is  replaced  by  23  per  cent  of  soft  brome  grass  (Bromus 
mollis},  9  per  cent  of  blue  grass  (Poa  pratensis},  3  per  cent  of 
meadow  pea  (Lathyrus  pratensis},  and  10  per  cent  of  wild  beaked 
parsley  (Anthriscus  sylvestris},  a  weed  practically  never  found 
on  any  other  plot. 

The  herbage  of  plot  7  (minerals)  in  1903  included  4.27  per  cent 
of  white  clover,  6.41  per  cent  of  red  clover,  .43  per  cent  of  bird-foot 
trefoil  (Lotus  corniculatus} ,  and  22.04  Per  cent  of  meadow  pea; 
while  plot  8  (minerals  except  potassium)  showed  1.25  per  cent  of 
white  clover,  1.38  per  cent  of  red  clover,  12.24  Per  cent  of  bird-foot 
trefoil,  and  3. 70  per  cent  of  meadow  pea.  Yarrow  (Achittea  mille- 
folium)  is  a  common  weed  (i  to  10  per  cent)  on  plots  6, 7,  8,  and  15. 

The  produce  of  plot  6  (changed  from  ammonium  salts  to  min- 
erals in  1869)  contained  sorrel  (Rumex  acetosa}  to  the  extent  of 
12. 1 1  per  cent  in  1862  and  24.27  per  cent  in  1867,  which  dropped 
to  7.51  percent  in  1872  and  to  5.24  per  cent  in  1903.  Plot  5  showed 
14.84  per  cent  of  sorrel  in  1903.  Lance-leaf  plantain  was  found  to 
the  extent  of  1.98  per  cent  on  plot  3  (unfertilized),  2.49  per  cent 
on  plot  4-1  (acid  phosphate),  5.85  per  cent  on  plot  8  (minerals 
except  potassium),  and  10.70  per  cent  on  plot  17  (sodium  nitrate), 
in  1903. 


THE    ROTHAMSTED    EXPERIMENTS  397 

The  number  of  species  found  in  1903  varied  from  10  on  plot  u-i 
to  47  on  the  unfertilized  plot  3.  On  plot  3  there  were  16  species 
varying  in  amount  from  .59  per  cent  to  5.98  per  cent,  while  3 
species  were  present  in  large  quantity;  namely,  20.15  Per  cent  °f 
quaking  grass  (Briza  media),  17.45  per  cent  of  sheep's  fescue  grass 
(Festuca  ovind),  and  13.81  per  cent  of  the  burnet  weed  (Poterium 
sanquisorbia} .  For  a  more  complete  discussion  of  the  produce 
from  The  Park,  see  pages  150  to  189  of  Director  A.  D.  Hall's  book, 
"  The  Rothamsted  Experiments." 

In  considering  the  financial  aspect  of  these  experiments, 
probably  we  cannot  do  better  than  to  take  2600  pounds  of  hay, 
the  average  of  plots  3  and  12  for  the  fifty  years,  as  a  general  basis 
of  comparison,  and  then  figure  the  increase  in  the  yield  of  mixed 
hay  at  $3  per  1000  pounds,  or  $6  per  ton,  which  allows  more 
than  $3  per  ton  for  the  extra  expense  of  harvesting,  stack- 
ing, baling,  and  marketing,  and  for  loss,  based  upon  the  lo-year 
average  price  for  central  United  States. 

On  this  basis  the  top-dressing  with  $3.48  worth  of  acid  phosphate 
produced  practically  no  effect,  the  average  increase  of  18  pounds 
of  hay  per  acre  being  worth  about  5  cents.  The  use  of  $12.90 
worth  of  ammonium  salts  on  plot  5  produced  $1.19  worth  of  hay; 
but  with  both  ammonium  salts  and  acid  phosphate  (plot  4-2)  the 
increase  was  worth  $3.98  (cost  $16.38).  The  addition  of  alkali 
salts  on  plot  7  has  increased  the  yield  over  plot  4-2  by  2197  pounds 
of  field-cured  hay,  worth  $6.59,  but  the  average  cost  of  the  potas- 
sium itself  is  more  than  $10. 

The  total  increase  on  plot  n-i  over  the  unfertilized  land  is 
4900  pounds,  or  $14.70,  while  the  total  cost  amounts  to  more  than 
$33.  As  an  average  the  minerals  on  plot  7  paid  less  than  half 
their  cost,  but  as  an  average  of  40  years  the  wheat  straw  was 
worth  about  $2.60  a  ton  as  a  fertilizer  for  the  increase  it  produced 
on  plot  13  above  plot  9;  or  as  a  substitute  for  nitrogen,  at  15 
cents  a  pound,  the  straw  was  worth  $4.85  a  ton.  (See  plot  n-i.) 

An  investment  of  $6.45  in  sodium  nitrate,  applied  alone  to  plot 
17,  returned  $4.14;  but,  if  the  hay  were  figured  at  $10  a  ton  net, 
it  would  have  been  worth  $6.90,  thus  showing  an  average  profit 
of  45  cents  per  acre  per  annum,  if  we  disregard  the  gradual  decrease 
in  yield  of  the  unfertilized  plots,  which,  however,  cannot  be  ig- 


398     INVESTIGATION   BY   CULTURE    EXPERIMENTS 

nored  in  planning  systems  of  permanent  agriculture.  With  hay  at 
$15  to  $25  a  ton,  which  are  common  prices  near  the  large  Eastern 
markets,  very  satisfactory  profits  may  be  made  by  top-dressing 
timothy  meadows  with  200  pounds  or  more  of  sodium  nitrate,  or 
with  perhaps  300  pounds  each  of  sodium  nitrate,  acid  phosphate, 
and  kainit.  As  a  rule,  smaller  applications  will  give  the  greater 
profit  for  the  money  invested  in  fertilizers,  but  larger  amounts  may 
yield  still  greater  profit  per  acre,  especially  when  the  price  of  hay 
is  $20  or  more. 

On  the  other  hand,  at  the  average  prices  that  can  be  counted  on 
for  the  Central  states,  the  data  from  the  Rothamsted  investigations 
afford  no  evidence  of  profit  from  the  use  of  commercial  nitrogen  or 
potassium  salts  or  acid  phosphate  or  any  combination  of  these  ma- 
terials, for  top-dressing  permanent  meadows. 


ROOT  CROPS  ON  BARN  FIELD,  ROTHAMSTED 

While  some  important  experiments  with  turnips  were  made  by 
Sir  John  Lawes,  even  before  1840,  the  principal  individual  plot 
records  date  from  1845;  and,  with  the  exception  of  three  years 
when  barley  was  grown  without  the  annual  fertilizing  (1853- 
1855),  root  crops  have  been  grown  every  year  on  this  part  of  Barn 
field. 

These  experiments  were  made  more  extensive  in  1856,  as  will 
be  seen  from  Table  71,  which  gives  certain  average  yields  in  four 
periods,  from  1845  to  1870,  and  the  detailed  records  of  sugar  beets 
grown  on  these  plots  from  1871  to  1875, tne  last  two  years  without 
the  full  yearly  application  of  fertilizers.  The  last  column  shows  the 
percentage  of  sugar  in  the  beets  in  1873,  which  was  apparently  a 
normal  season  and  the  last  in  which  the  fertilizers  were  applied 
in  full  for  the  sugar  beets.  From  these  data,  the  sugar  per  acre  can 
be  computed,  but  it  should  be  kept  in  mind  that  the  yield  of  beets 
is  given  in  tons  of  2240  pounds  and  for  roots  with  only  the  leaves 
removed.  The  fertilizers  applied  were  in  general  the  same  as  those 
specified  in  Table  716. 

It  will  be  seen  that  the  first  year  sugar  beets  were  ever  grown  on 
this  field  the  yield  varied  from  5.05  tons  to  28.90  tons,— a  fact  which 


THE    ROTHAMSTED    EXPERIMENTS 


399 


TABLE  71.     ROOT  CROPS  ON  BARN  FIELD,  ROTHAMSTED 
Yield  per  Acre  of  Roots,  in  Long  Tons  (2240  Ib.) 


to 

IK 

1 

to 

o 

O^ 

«5 

O 

SUGAR  BEETS  (Vilmorin's) 

Son.  TREATMENT  EVERY  YEAR 

^1 

>? 

00 

^ 

(About  43  Ib.  N  till  1860  ;    then  86 

^   0 

cTH 

<.  O 

srb 

fc.^ 

0  3 

<.   O 

tffc 

,Q. 

PLOT 

Ib.     Nothing  applied   for   the  Bar- 

i« 

2  w 

.ra 
j>"^ 

i  ° 

c 

a 

a 

c 

c 

lrf! 

No. 

ley,  and  no  Manure,  Rape  Cake,  or 

§0? 

Doo 

<  in 

0!    t^ 

poo 

o 

o 

r  . 

£ 

0 

£ 

«" 

Nitrogen  applied  for  187,4  or  1875. 

H£ 

HT 

>°Z 

f  1 

H 

M 

r1 

H 

c-1 

C  (v 

About    300  Ib.    Potassium    Sulfate 

w  S. 

W 

w  *° 

M 

N 

m 

^> 

10 

till  1871  ;  afterward  500  Ib.) 

O 

g<S 

3 

S" 

t^ 

00 

r~ 

00 

t^ 

00 

t^ 

00 

*~ 

00 

a  M 
w  ^ 

£  "* 

•t 

in 

H 

C/5 

W 

300 

c/3  « 

Oi 

Farm  manure  (i4  long  tons)  .     .     . 

_ 

6.20 

18.15 

I5-65 

15.10 

10.80 

17-25 

12.  1 

02 

Manure  and  phosphate     .... 

— 

— 

— 

6.35 

14.65 

16.00 

14.30 

13-15 

15-55 

2-3 

03 

Unfertilized  since  1845      .... 

1.20 

2.30 

18.8 

•55 

7-SS 

7-Ss 

5-05 

5.10 

5-45 

3-1 

04 

Minerals  (P,  K,  Mg,  Na,  S,  Cl)  .     . 

8.0  s 

7.85 

20.8 

2.80 

7-S5 

6.70 

S-io 

6.50 

5-45 

3-1 

os 

Acid  phosphate  

8.80 

7-45 

21.0 

2.60 

5-00 

6.85 

5-25 

5-95 

5-55 

3-5 

06 

Phosphate  and  pot.  sul  

8.00 

6.80 

18.8 

2-35 

5-05 

6.30 

4.60 

5-55 

5-20 

3-6 

07 

Phos.,  pot.,  and  amm.  salts  (8  Ib.  N) 

— 

— 

—  • 

2.60 

5-90 

6-75 

5-95 

6.70 

5-55 

3-7 

O8 

Unfertilized  since  1853      .... 

— 

— 

— 

I-J5 

7.50 

5.20 

4-55 

S-oo 

4-75 

3-9 

Ni 

Nitrate  and  farm  manure       .     .     . 

— 

— 

— 

7-45 

27-65 

23-45 

20.25 

11.70 

19.90 

.6 

N2 

Nitrate,  manure,  and  phosphate    . 

— 

— 

—  . 

7-65 

25-80 

24.30 

21.50 

7-45 

19.90 

.2 

Ni 







•95 

22.  15 

21.35 

14*25 

3-io 

9.25 

.3 

N4 

Nitrate  and  minerals    





— 

s.io 

22.75 

20.10 

16.45 

8.80 

9.40 

•4 

NS 

Nitrate  and  phosphate      .... 

— 

— 

—  . 

4-65 

20.95 

19.30 

18.40 

7-50 

9-95 

•9 

N6 

Nitrate,  phosphate,  and  pot.  sul.    . 

— 

— 

— 

4-55 

21.25 

16.80 

15-85 

8.05 

8.20 

.8 

N7 

Nitrate,  phos.,  pot.,  amm.  salts  .     . 

— 

— 

— 

4-65 

20.95 

17.00 

16.70 

9-25 

8.10 

.1 

N8 

Sodium  nitrate    

— 

— 

— 

1.65 

11.65 

15-30 

12.45 

7-65 

7.20 

•3 

Ai 

Amm.  salts  and  farm  manure    .     . 





— 

8.40 

22.05 

22.70 

22.10 

11-35 

21.00 

.7 

A2 

Amm.  salts,  manure,  phosphate    . 

—  . 

— 

— 

8.2=; 

21-75 

22.00 

19.20 

9-25 

1  8.8s 

•o 

A3 

Ammonium  salts     

1-35 

3.85 

20.5 

•65 

15-3° 

iS-iS 

9-15 

3-35 

8.00 

•4 

A4 

Amm.  salts  and  minerals     .... 

9-75 

9-45 

22.5 

4.60 

17-5° 

15-50 

12.50 

7-50 

7.80 

•4 

As 

Amm.  salts  and  phosphate     .     .     . 

9.90 

8.70 

23-0 

3-80 

15.20 

14-25 

10.95 

7-30 

7.80 

•S 

A6 

Amm.  salts,  phos.,  and  pot.  sul. 

c-.8o 

8.70 

20.5 

4-25 

17.20 

14-35 

12.90 

8.05 

7-05 

•  5 

A7 

Amm.  salts,  phos.,  and  pot.  sul. 

— 

— 

4.60 

18.40 

15-45 

13.00 

8-75 

7-30 

.0 

A8 

Ammonium  salts     

— 

•  — 

—  • 

I.  TO 

16.10 

13-50 

8.40 

6.50 

6.05 

•S 

AC  i 

Amm.  salts,  rape  cake,  and  manure 



— 

— 

8.80 

2(5.20 

26.40 

22.75 

13-35 

2-35 

•7 

AC  2 

Amm.  salts,  cake,  manure,  phos.    . 

— 

.  —  . 

— 

8.70 

25.10 

25-45 

23-35 

12.25 

0-45 

.8 

AC  3 

Amm.  salts  and  rape  cake    .     .     . 

5  -So 

7.00 

24-5 

3-30 

19.50 

20.40 

15-60 

2-55 

4-05 

.7 

AC  4 

Amm.  salts,  cake,  and  minerals  .     . 

10.25 

13-05 

2S-0 

6.60 

22.75 

23.40 

20.15 

1  0.60 

2.70 

.6 

ACS 

Amm.  salts,  cake,  and  phosphate 

10.05 

I  J.2O 

26.8 

5.80 

IQ.  00 

18.55 

M-75 

1-75 

3-85 

.0 

AC  6 

Amm.  salts,  cake,  phos.,  and  pot.   . 

10-35 

I2.40 

25-0 

6.30 

23-55 

22.80 

20.  IO 

9-50 

2.40 

•3 

AC  7 

Amm.  salts,  cake,  phos.,  and  pot.   . 



6.75 

21.00 

23-45 

19.80 

11.70 

i.  8S 

-S 

ACS 

Amm.  salts  and  rape  cake    .     .     . 

— 

—  • 



3-05 

17-95 

19.60 

15-10 

7-30 

2.10 

.3 

Ci 

Rape  cake  and  farm  manure    .     . 



_ 



8.00 

28.90 

22.25 

23-50 

14.50 

9-65 

.0 

C2 

Rape  cake,  manure,  and  phosphate 

— 





7.80 

25.2O 

20.75 

2I.9O 

13-05 

8.50 

•9 

C3 

Rape  cake       

6-55 

7-70 

2S-9 

3-4° 

20.80 

16.15 

14.65 

3-9S 

I.8S 

•5 

C4 

Rape  cake  and  minerals   .... 

II.  IO 

12-35 

25.2 

5-40 

21-35 

17.90 

I6.O5 

8.10 

0.15 

•S 

cs 

Rape  cake  and  phosphate    .     .     . 

IO.9O 

10.50 

27.0 

5.00 

18.95 

15.90 

13-95 

5.85 

1.  10 

.8 

C6 

Rape  cake,  phos.,  and  pot.  sul.  .     . 

I0.8S 

11.7*0 

25.0 

5-15 

2I.OO 

15.85 

14.70 

7-65 

O.IO 

•3 

C7 

C8 

Cake,  phos.,  pot.,  amm.  salts    . 
Raoe  cake 



— 

5-45 
1.70 

21-35 

20.  *<; 

15-50 

iq.oo 

15.85 
12.10 

8.20 

•?.6o 

0.30 

1.  00 

•4 

.4 

does  not  suggest  that  the  principal  office  of  farm  manure  and  rape 
cake  is  to  destroy  toxic  excreta  from  the  roots  of  sugar  beets. 

In  Table  716  are  recorded  the  yields  of  mangel  roots  since  1876, 
in  averages  of  5-year  periods  for  30  years,  and  for  single  years 
subsequently.  (Swede  turnips  were  grown  in  1908,  after  the  man- 
gels failed,  the  yield  of  turnips  varying  from  1.34  to  13.01  tons.) 


TABLE  713.     MANGEL-WURZEL  ON  BARN  FIELD,  ROTHAMSTED 
Yield  per  Acre  of  Roots,  in  Long  Tons  (2240  Ib.) 


PLOT 

No. 

Son.  TREATMENT  EVERY 
YEAR 

(Except  no  Nitrogen  Salts 
in  1885  and  1901;    500  Po- 
tassium Sulfate   app  led    to 
Plots  2  for  1895  and  since, 
and  Minerals  with  No  Potas- 
sium or  Extra  Nitrogen  ap- 
plied to  Plots  7  for  1003  and 
Since) 

NITROGEN  PER  ACRE, 
(Pounds) 

TOTAL  SALTS  PER  ACRE, 
(Pounds) 

AVERAGE  YIELDS 

LATE  YIELDS 

1876 
to 
1880 

1881 
to 

1884 

1886 
to 
1800 

1891 
to 
1895 

1896 
to 
1900 

IOO2 

to 

1905 

1906 

1907 

Tur- 
nips, 
1908 

Oi 

02 

03 
04 

os 

06 
07 

08 

Farm  manure  (14  long  tons) 
Manure  and  phosphate  .     . 
Unfertilized  since  1845   .    . 
Minerals  (P,  K,  Mg,  Na,  S,  Cl) 
Acid  phosphate      .... 
Phosphate  and  pot.  sul.  .     . 
Phos.,  pot.,  and  amm.  salts 
(S  Ib  N)         

(?) 
(?) 
none 
none 
none 
none 

8 
none 

392 
none 
1292 
392 
892 

929 
none 

14.60 
15-05 
4-30 
5-70 
5-05 
4-50 

6.00 

3-45 

16.75 
16.60 
4-85 
5-8o 
5-35 
4-75 

6.60 
4-25 

15-75 
i6-35 
4-iS 
4-75 
4.70 
4.20 

5-05 
3-50 

22.20 
21.80 
6.35 
5.10 
S-oo 
4-85 

6.00 
4-40 

17.40 
18.95 
6-35 
5-45 
S-oo 
4-40 

5-85 
4.05 

18.68 
20.69 

4.06 
4.66 
3-63 

4.44 
3-i3 

20.39 
20.94 

5-Si 
5-9i 
5-31 

5-44 
3-67 

26.00 
26.52 

5-95 
6.21 

5-78 
6-59 

s-i"; 

11.69 
13.01 

4.07 
3-9i 
3-53 

8.76 
1-34 

Unfertilized  since  1853    .     . 

Ni 

N2 

N3 

£4 
>•  s 

N6 

N7 
N8 

Nitrate  and  farm  manure    . 
Nitrate,  manure,  and  phos- 

(?) 

(?) 
86 
86 
86 

86 

94 

86 

550 

942 
SSo 
1842 
942 

1442 

M79 
S5Q 

20.85 

22.90 
I3-30 
19.40 
16.45 

I7-30 
I7-65 

II.OO 

23-45 
25-05 

I2.QO 
I7-70 
14.65 

14-55 
14.80 

10.15 

20.95 

22.55 
13-65 
18.40 
15.60 

15.20 

15.80 
10.90 

29-65 

25.80 
12.80 
14.20 
12.90 

12.05 

12.  2O 

6.00 

26.90 

28.05 
18.25 
18.95 
16.15 

16.45 

16.05 
11.45 

30.32 
31-24 

22.51 
18.57 

19.84 

21.03 
1  1.  06 

30.31 
30.24 

13-08 
14.30 

17-23 

21.92 
10.25 

41.42 
42.13 

30.46 
24.62 

25-05 

26.54 
1  8.60 

12.73 
12.49 

11.19 
9-30 

8.03 

8.76 
2.79 

Sodium   nitrate      .... 
Nitrate  and  minerals  .     .     . 
Nitrate  and  phosphate    .     . 
Nitrate,  phosphate,  and  pot. 
sul  •.     .     . 

Nitrate,  phos.,  pot.,  amm. 
salts            

Sodium  nitrate       .... 

Ai 

A2 

A3 
A4 
As 
A6 
A7 
A8 

Amm.  salts  and  farm  manure 
Amm.  salts,  manure,  phosphate 
Ammonium  salts   .... 
Amm.  salts  and  minerals  .     . 
Amm.  salts  and  phosphate  . 
Amm.  salts,  phos.,  and  pot.  sul. 
Amm.  salts,  phos.,  and  pot.  sul. 
Ammonium  salts    .     .     .     . 

(?) 
(?) 
86 
86 
86 
86 
04 
f6 

400 
792 
400 
1692 
792 
1292 
1329 
400 

23.00 
22.70 
8.15 
iS-SS 
9.70 
14.00 
14.65 
7-05 

21-35 
21.45 
6.00 
16.10 
8.00 
14.40 
14.65 
5-45 

2O.  IO 

19.75 

6-35 
14.80 
8.10 
13-65 
14.70 
6.15 

25.00 
22.60 
4-95 
12.80 
5-70 
12.80 
13-25 
4-30 

18.70 
23-75 
6-95 
14-95 
6.60 
14.65 
14-85 
6.  20 

24-34 
30-15 

16.08 
6.93 
15.46 
16.51 
6.01 

25.69 
30-95 

12.29 
3-85 
16.38 
16.95 
6.36 

33-52 

41.68 

26.68 
10.88 
25-22 
26.52 
9-87 

11.05 
11.94 

11.48 
6.42 
10.07 
10.84 
2-53 

AC  i 
AC  2 

AC  3 
AC  4 
ACs 
AC  6 

AC? 

ACS 

Amm.  salts,  rape  cake,  and 
manuYe       
Amm.  salts,  cake,  manure, 

(?) 

(?) 

i«3 
183 
183 

183 

IQI 

183 

400 

79 
400 
169 
79 

129 

1329 

400 

24-95 

24.10 
11.80 
24.40 
12.50 

21.05 
20.80 

12.00 

25-I5 

24.90 
0-95 
26.00 
11.25 

24.10 
23.60 

21-45 

21-55 
10.40 
22.35 
10.50 

19.65 

20.50 
n.  so 

28.55 

26.25 
9-85 
28.65 
10.35 

25-80 

24.25 

p.  7" 

20.50 

25.80 
7-85 
24.2°; 
7.60 

20.70 

2I.OO 
8.70 

26.54 
34-15 

3T-52 

8.44 
27-77 

29-75 

8.22 

26.82 
32.06 

26.31 
6-57 

25.28 

28.19 
8.05 

34-29 

43-52 

40.97 
11.26 

35-88 

34.38 
10.^0 

10.98 
11.19 

n-55 
5-45 

9-52 

9-S3 
4.61 

Amm.  salts  and  rape  cake   . 
Amm.  salts,  cake,  and  minerals 
Amm.  salts,  cake,  and  phos. 
Amm.  salts,  cake,  phos.,  and 

Amm.  salts,  cake,  phos.,  and 
pot  

Amm.  salts  and  rape  cake  . 

Ci 

C2 

£3 

cl 

C6 

c? 

C8 

Rape  cake  and  farm  manuie 
Rape  cake,  manure  and  phos. 
Rape  cake  (200x3  pounds)    . 
Rape  cake  and  minerals  . 
Rape  cake  and  phosphate   . 
Rape  cake,  phos.,  and  pot.  sul 
Cake,  phos.,  pot.,  amm.salts 
Rape  cake  (2000  pounds)  . 

<n 
(?) 

97 
97 
97 
97 
105 
97 

39 

129 
39 
89 
92 

21.05 
22.15 
IT.  2O 
18.90 
12.40 
16.25 
16.90 
10.  IO 

25.15 
24.40 
11.15 
20.45 
12.50 
>9-35 
20.75 
10.35 

21-55 
21.40 
10-75 
19-35 
11.50 
16.30 
I7-I5 
9-75 

20.80 
28.25 
11.05 
26.11; 
II.So 
22.30 
22.65 
n-45 

22.25 
24-75 

8-95 
20.85 
8.00 
18.05 
18.15 
8.30 

25-13 
30.57 

24.08 
9.89 

21.  l6 

26.83 
8.84 

25.26 
30.10 

23-18 
8.93 
21.66 
24.68 
9-93 

35-02 
40.74 

33-09 
15-43 
28.15 
30-59 
I3-24 

0-73 
10.36 

11.03 
5.i6 
9.26 
9-43 
4.23 

These  data  are  presented  for  examination  by  the  reader,  and  only 
a  few  special  points  will  be  referred  to  here.  The  records  of  1885 
and  1901  are  not  included  in  the  averages  because,  owing  to  un- 


THE    ROTHAMSTED   EXPERIMENTS  401 

favorable  conditions,  no  nitrogen  salts  were  applied  for  those  years. 
For  the  same  reason  the  records  for  plots  N$  to  N8  and  A3  to  A8 
are  not  used  for  1903.  The  Rothamsted  Station  reports  that, 
owing  to  very  heavy  rains  in  November,  1894,  flooding  the  lower 
parts  of  the  experimental  mangel  field,  and  washing  soil  from  the 
farm-manure  plots,  especially  on  to  plot  03,  and  to  a  less  degree 
on  to  plot  N3,  there  is  no  doubt  that  the  results  from  those  plots 
are  too  high  for  1895  and  each  year  since.  Of  late  years  no  data  are 
reported  from  plot  3,  but  the  No.  8  plots  are  sufficient. 

As  explained  in  the  table,  500  pounds  of  potassium  sulfate  has 
been  applied  since  1895,  in  addition  to  the  other  regular  treatments, 
to  plots  Oa,  N2,  A2,  AC2,  and  €2;  and  for  1903  and  since  the 
application  of  potassium  and  the  extra  nitrogen  (8  pounds  per  acre) 
has  been  discontinued  on  plots  Oy,  Ny,  Ay,  ACy,  and  Cy,  but  in- 
stead those  plots  have  received  the  full  minerals,  except  potassium. 

The  "  minerals  "  regularly  include  392  pounds  of  acid  phosphate, 
500  pounds  of  potassium  sulfate,  200  pounds  of  magnesium  sul- 
fate, and  200  pounds  of  common  salt  (sodium  chlorid) ;  but  from 
1896  to  1902  the  acid  phosphate  was  replaced  throughout  by  slag 
phosphate. 

The  mangel  leaves  are  each  year  spread  over  the  respective 
plot,  and  thus  returned  to  the  soil. 

It  had  been  suggested  that  plants  with  large  leaf  surface,  like 
the  mangel,  could  probably  secure  sufficient  nitrogen  from  the  air, 
in  the  form  of  ammonia  or  possibly  as  free  nitrogen,  for  their  full 
requirement,  provided  a  small  amount  of  available  nitrogen  was 
furnished  to  give  the  plants  a  good  start;  and  because  of  this  the 
special  8  pounds  of  nitrogen  were  applied  to  plots  Oy,  Ny,  Ay,  and 
Cy  until  1902,  after  which  the  treatment  for  those  plots  was 
changed  as  stated. 

Where  no  other  nitrogen  was  supplied  (plot  Oy),  the  8  pounds 
increased  the  yield  of  mangel-wurzel  by  1.36  tons  as  an  average  of 
25  years.  At  $1.50  per  long  ton  this  increase  would  be  worth  $2.04 
per  acre,  while  the  nitrogen  would  cost  only  $1.20  at  15  cents  a 
pound.  Two  points  must  be  kept  in  mind,  however;  first,  that  the 
total  crop  on  plot  O8  was  produced  at  a  loss;  second,  that  the 
increase  from  the  phosphorus  and  potassium  applied  to  plot  O6 
was  worth  less  than  10  per  cent  of  the  cost  of  those  elements. 


402     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

Where  organic  nitrogen  was  applied  in  rape  cake,  the  additional 
8  pounds  of  soluble  nitrogen  produced  only  two  thirds  of  a  ton  in- 
crease, which  would  be  worth  less  than  the  cost  of  the  nitrogen,  at 
the  price  used. 

It  may  be  stated  that  the  first  crop  of  mangel-wurzel  (1876)  on 
plot  O8  was  5.45  tons,  while  the  same  plot  produced  6.95  tons  in 
1898  and  7.75  tons  in  1900.  Plot  N4  produced  25.05  tons  in  1876, 
and  several  plots  produced  still  higher  yields,  the  highest  being 
31.45  tons  on  plot  ACi. 

Since  1904,  the  200  pounds  of  sodium  chlorid  has  been  omitted 
from  one  half  of  plot  N4,  which  receives  sodium  in  the  nitrate. 
The  subsequent  yields  for  this  half  have  been  24.69,  16.69, an^  35- Z5 
tons  per  acre  for  the  years  1905-1907,  or  distinctly  more  than  where 
the  common  salt  was  included,  as  will  be  seen  from  Table  716. 

Of  special  interest  is  the  evident  effect  of  the  potassium  applied 
to  plots  2  for  1895  and  since.  The  previous  records  indicate  that 
the  heavy  applications  of  manure  had  furnished  sufficient  phos- 
phorus for  the  crops  grown,  and  the  yields  since  1895  plainly  show 
that  potassium  was  the  limiting  element  wherever  nitrogen  had 
been  applied  in  addition  to  the  farm  manure.  Since  phosphorus 
is  also  applied  to  plots  2,  it  is  impossible  to  determine  what  in- 
crease would  have  been  made  by  potassium  without  the  added 
phosphorus;  but  on  plots  A2,  AC2,  and  C2  the  yields  since  1895 
have  averaged  about  5  tons  more  than  on  the  No.  i  plots.  The 
sodium  applied  in  the.  sodium  nitrate  on  plot  Ni  appears  to  produce 
almost  the  same  effect  as  the  potassium  applied  (since  1895)  to 
plot  A2.  It  will  be  observed  that  phosphorus  produced  an  appre- 
ciable effect  on  N2  from  1876  to  1890. 

As  an  average,  one  ton  (2000  pounds)  of  mangel-wurzel  contains 
about  3.6  pounds  of  nitrogen,  .5  pound  of  phosphorus,  and  6.6 
pounds  of  potassium,  and  the  average  requirements  for  such  an 
enormous  crop  as  grew  on  plot  AC2  in  1907  would  be  about  175 
pounds  of  nitrogen,  24  pounds  of  phosphorus,  and  330  pounds  of 
potassium,  for  the  roots  only.  If  we  assume  the  farm  manure  to 
have  10  pounds  of  nitrogen,  2  pounds  of  phosphorus,  and  8  pounds 
of  potassium  per  ton  of  2000  pounds,  the  annual  applications  now 
being  made  to  plot  AC2  contain  about  340  pounds  of  nitrogen, 
60  pounds  of  phosphorus,  and  360  pounds  of  potassium.  On  this 


THE    ROTHAMSTED    EXPERIMENTS 


403 


basis,  the  crop  of  1907  required  for  the  roots  alone,  180  pounds 
more  potassium  than  was  supplied  in  the  manure  and  rape  cake; 
and  it  seems  remarkable  that  the  141  pounds  of  sodium  on  plot 
Ni  produced  almost  as  great  an  effect  as  the  210  pounds  of 
potassium  on  plot  AC 2. 

It  is  of  interest  to  note  that  the  total  supply  of  potassium  con- 
tained in  the  surface  soil  (6|  inches  deep)  of  the  peat  lands  of  New 
York  or  Illinois,  for  example,  would  be  sufficient  for  less  than  10 
such  crops  as  were  grown  on  plots  Ni,  N2,  A2,  AC2,  AC4,  and  C2, 
of  Barn  field,  Rothamsted,  in  1907;  and  that  even  the  total  potas- 
sium in  2  million  pounds  of  the  most  common  type  of  soil  in  the 
Illinois  wheat  belt  (gray  silt  loam  prairie,  lower  Illinoisan  glacia- 
tion)  would  be  sufficient  for  only  75  such  crops,  although  it  would 
be  sufficient  for  50  bushels  of  wheat  per  acre  every  year  for  19 
centuries,  if  the  straw  is  returned  to  the  land. 

ABANDONED  LANDS  AT  ROTHAMSTED 

Since  1882,  a  piece  of  Broadbalk  field,  which  had  been  cropped 
with  wheat  every  year  since  1844,  has  been  abandoned  to  nature, 
except  that  trees  and  shrubs  have  been  kept  out.  Likewise,  a 
piece  of  Geescroft  field,  which  had  been  used  for  beans  from  1847 
to  1881  (only  four  crops  grown  during  the  last  n  years),  and  for 
clover  from  1882  to  1885,  has  been  abandoned  to  volunteer  vege- 
tation since  1885. 

Nothing  has  been  harvested  from  these  pieces  of  land,  not  even 
by  pasturing,  since  they  have  been  left  to  "  lie  out,"  or  "  run  wild." 

The  most  marked  difference  that  has  developed  between  the 
herbage  of  the  two  fields  is  the  absence  of  legumes  on  Geescroft 
and  the  abundance  of  legume  plants  on  Broadbalk,  although 
Broadbalk  was  abandoned  with  a  wheat  crop  standing  on  it  (of 
which  some  volunteer  plants  continued  to  appear  for  three  or  four 
years) ,  while  Geescroft  was  in  clover  when  abandoned.  Observers 
(including  Sir  John  Lawes  *)  commonly  attributed  the  absence  of 

1  In  1900,  when  I  had  the  deeply  appreciated  privilege  of  being  shown  over  the 
Rothamsted  fields  by  Sir  John  Lawes  (about  a  month  before  his  sudden  death), 
he  climbed  the  fence  like  a  boy,  to  take  me  into  Geescroft  field  and  point  out  a  few 
legume  plants  (of  a. single  species)  the  development  of  which  he  had  been  watching 
for  two  or  three  years.  —  C.  G.  H. 


404    INVESTIGATION   BY   CULTURE   EXPERIMENTS 


legumes  on  Geescroft  to  the  fact  that  the  land  was  legume  "  sick  " 
from  the  effort  to  grow  beans  for  more  than  30  years,  although  some 
good  crops  of  clover  were  grown  from  1882  to  1885. 

Some  interesting  data  concerning  these  two  abandoned  fields 
are  given  in  Table  72. 

TABLE  72.      ROTHAMSTED  FIELDS,  ABANDONED  TO  NATURE  FOR  20  YEARS 


LAND 

BROADBALK  FIELD                       GEESCROFT  FIELD 

Character  of  Herbage,  June,  1903 

Grasses  

59.64  per  cent 
25.31  per  cent 
15.05  per  cent 

95.26  per  cent 
.43  per  cent 
4.31  per  cent 

Legumes      

Miscellaneous  .... 

Percentages  in  Soils  from  Broadbalk  (1881)  and  Geescroft  (1883) 


DEPTH  (Inches) 

0-9 

9-18 

18-27 

0-9 

9-18 

18-27 

Total  nitrogen      .     .     . 
Organic  carbon    .     .     . 

.108 
i-i43 

.070 
.624 

.058 
.461 

.I081 
I.  Ill 

.074 
.600 

.060  _ 
•44?' 

Percentages  in  Soils  in  1904 


Total  nitrogen      .     .     . 

•145 

.096 

.084 

•131 

.083 

.065 

Organic  carbon    .     .     . 

!-233 

•°73 

•551 

1.494 

.624 

-438 

Calcium  carbonate    .     . 

3-325 

.126 

.160 

•I31 

~ 

'This  percentage  was  .108  in  1883  and  .115  in  1885,  the  clover  crops  having 
been  harvested  and  removed  during  the  two  years. 

It  seems  that  the  practice  of  chalking  the  land,  which  prevailed 
at  Rothamsted  a  century  or  more  ago,  had  not  extended  to  Gees- 
croft  field,  and  without  much  doubt  this  has  been  the  chief  factor 
in  determining  the  character  of  the  herbage,  in  part  because  of  the 
chemical  reaction  of  the  soil  and  in  part  because  of  the  physical 
difference,  the  Geescroft  land  being  close-textured,  poorly  drained, 
wet,  and  cold,  while  the  Broadbalk  soil,  because  of  the  lime  present, 
flocculates  or  granulates  and  drains  well.  (The  adjoining  regular 
plots  are  tile-drained  on  Broadbalk.) 

Hall  states  that  "  where  nitrate  of  soda  had  been  used  (on  Gees- 


THE   ROTHAMSTED   EXPERIMENT  405 

croft  field),  the  land  became  specially  difficult  to  manage,  remain- 
ing persistently  wet,  and  then  drying  out  with  an  excessively  hard 
crust." 

From  any  estimates  that  can  be  based  upon  the  percentages  of 
nitrogen  found  in  samples  of  soil  from  these  fields,  very  large  in- 
crease is  shown;  in  fact,  much  larger  than  can  be  accounted  for 
by  any  existing  knowledge  concerning  nitrogen  fixation.  It  is 
questioned  if  the  samples  collected  in  1904  are  strictly  comparable 
with  those  taken  20  years  before,  because  of  the  increasing  porosity 
and  looseness  of  the  soil.  Thus,  the  9-inch  stratum  of  1881  might 
occupy  10  inches  or  more  in  1904. 

Director  Hall  estimates  that  Geescroft  field  (even  without 
legume  plants)  has  gained  a  quantity  of  nitrogen  "  which  at  the 
lowest  reckoning  amounts  to  about  25  pounds  per  acre  per  year," 
and  adds: 

"The  nitrogen  brought  down  in  the  rain  would  account  for  perhaps  5  Ibs. 
per  acre  per  annum,  a  little  more  will  come  in  the  form  of  dust,  bird-droppings, 
and  other  casual  increments,  while  some  may  be  due  to  fixation  of  atmospheric 
nitrogen  by  bacteria  in  the  soil  not  associated  with  leguminous  plants,  like  the 
Azotobacter  chroococcum  of  Beijerinck  and  Winogradsky's  Clostridium  pasto- 
rianum.  Two  other  causes  may  be  at  work,  the  absorption  of  atmospheric  am- 
monia by  soil  and  plant,  and  the  rise  of  nitrates  from  the  subsoil." 

In  the  author's  opinion,  the  two  most  important  factors  involved 
are  the  difficulty  of  securing  comparable  samples  and  the  mechani- 
cal addition  of  foreign  substances,  especially  the  dust  of  summer,  and 
the  dirty,  drifting  snow  of  winter,  light  trash  (leaves,  weeds,  etc.), 
which  blow  about  until  they  find  a  lodging  place  in  such  a  small 
"  wilderness  "  as  the  abandoned  portions  of  these  fields  furnish. 
An  extreme  illustration  of  this  is  found  in  a  Rothamsted  note 
concerning  the  potato  tops  on  Hoos  field  in  1877: 

"Tops  withered,  not  weighed,  each  lot  spread  on  its  own  plot,  but  high  wind 
(October  14)  blew  all  off  before  plowing." 

One  experienced  in  farm  practice  will  easily  recall  conditions 
under  which  field  dust  is  drifted  by  the  wind.  The  extent  varies 
from  the  cloud  which  follows  the  harrow  to  the  dust  storm,  during 
which  a  field,  even  of  clay  loam,  in  certain  mechanical  condition, 
may  lose  very  appreciable  amounts  of  its  best  soil,  which  requires 


4o6    INVESTIGATION    BY   CULTURE   EXPERIMENTS 

for  its  deposition  and  accumulation  only  an  undisturbed  lodging 
place,  and  dirty  snowbanks  form  in  such  places  near  open  fields. 

NOTES    ON    THE    ROTHAMSTED    FlELD    EXPERIMENTS 

The  records  herein  given  must  be  considered  at  best  as  summaries 
of  the  Rothamsted  field  experiments.  Aside  from  the  experiments 
already  mentioned,  beans  were  grown  every  year  from  1849  to 
1859,  and  oats  every  year  (except  1877,  fallow)  from  1869  to  1878, 
under  different  systems  of  fertilizing,  on  Geescroft  field.  The 
average  yield  of  oats  for  the  five  years  (1869  to  1873)  range,  in 
bushels  per  acre,  from  19.9  (unfertilized)  and  24.5  (minerals)  to 
47  (ammonium  salts)  and  59  (ammonium  salts  and  minerals) ; 
and  for  the  other  four  years  from  13.1  (minerals)  and  13.8  (unfer- 
tilized) to  28.9  (ammonium  salts)  and  38  (ammonium  salts  and 
minerals) . 

No  oats  were  grown  on  this  field  from  1847  to  1868,  and  the  first 
crop  of  oats  (1869)  varied,  in  bushels  per  acre,  from  36.6  (unfer- 
tilized) and  45  (minerals)  to  56.1  (ammonium  salts)  and  75.2 
(ammonium  salts  and  minerals).  The  records  for  the  9  years, 
1860  to  1868,  are:  fallow,  wheat,  wheat,  fallow,  beans,  wheat, 
beans,  wheat,  wheat;  with  no  fertilizers  applied  during  those 
years  except  farm  manure  for  the  beans  in  1864. 

Experiments  with  legume  crops,  especially  with  beans  and  clover, 
have  been  in  progress  on  Geescroft  or  Hoos  fields  (or  both)  most  of 
the  time  since  1847.  In  summarizing  their  experimental  results 
after  more  than  fifty  years,  Lawes  and  Gilbert  recorded  the 
following  statements  (Rothamsted  Memoranda,  published  in 
1901) : 

"When  the  same  description  of  leguminous  crop  is  grown  too  frequently  on 
the  same  land,  it  seems  to  be  peculiarly  subject  to  disease,  which  no  conditions 
of  manuring  that  we  have  hitherto  tried  seem  to  obviate." 

"The  general  results  of  the  experiments  on  ordinary  arable  land  in  the  field 
has  been  that  neither  organic  matter  rich  in  carbon  as  well  as  other  constitu- 
ents, nor  ammonium  salts,  nor  nitrate  of  soda,  nor  mineral  constituents,  nor  a 
complex  mixture,  supplied  with  manure,  availed  to  restore  the  clover-yielding 
capabilities  of  the  land;  though,  where  some  of  these  were  applied  in  large 
quantity,  and  at  considerable  depths,  the  result  was  better  than  when  they  were 
used  in  only  moderate  quantities,  and  applied  only  on  the  surface. 


THE   ROTHAMSTED   EXPERIMENTS  407 

"On  the  other  hand,  it  is  clear  that  the  soil  in  the  garden,  which  at  the  com- 
mencement contained  in  its  upper  layers  about  four  times  as  much  nitrogen  as 
the  arable  land,  and  would  doubtless  be  correspondingly  rich  in  other  constitu- 
ents, has  supplied  the  conditions  under  which  clover  can  be  grown  year  after 
year  on  the  same  land  for  many  years  in  succession. 

"The  results  obtained  on  the  soil  in  the  garden  seem  to  sliow  that  what  is 
called  'clover  sickness,'  cannot  be  due  to  the  injurious  influence  of  excreted 
matters  upon  the  immediately  succeeding  crop. 

"That  clover  frequently  fails  coincidently  with  injury  from  parasitic  plants 
or  insects  cannot  be  disputed;  but  it  may  be  doubted  whether  such  injury 
should  be  reckoned  as  the  cause,  or  merely  the  concomitant,  and  an  aggravation, 
of  the  failing  condition." 

"When  land  is  not  what  is  called  'clover-sick,'  the  crop  of  clover  may  fre- 
quently be  increased  by  top  dressings  of  manure  containing  potash  and  super- 
phosphate of  lime ;  but  the  high  price  of  salts  of  potash,  and  the  uncertainty  of 
the  action  of  manures  upon  the  crop,  render  the  application  of  artificial  manures 
(as  top  dressings)  for  clover  a  practice  of  doubtful  economy. 

"When  the  land  is  what  is  called  'clover-sick,'  none  of  the  ordinary  manures, 
whether  '  artificial '  or  natural,  can  be  relied  upon  to  secure  a  crop. 

"So  far  as  our  present  knowledge  goes,  the  only  means  of  securing  a  good 
crop  of  red  clover  is  to  allow  some  years  to  elapse  before  repeating  the  crop 
upon  the  same  land." 

In  his  book  on  the  "Rothamsted  Experiments"  (page  146), 
Director  Hall  gives  the  complete  data  and  the  following  summary 
of  the  clover  grown  year  after  year  on  a  small  plot  of  rich  garden 
soil  at  Rothamsted: 

RED  CLOVER  ON  RICH  GARDEN  SOIL,  ROTHAMSTED 
Pounds  per  Acre 


YEAH 

s 

AIR  DRY  HAY 

DRY  MATTER 

NITROGEN  IN 
CROPS 

Average  of 
Average  of 

25  years 
25  years 

(1854-1878)     . 
(1879-1903)     . 

7664 
3924 

M? 
3270 

179 
101 

During  the  fifty  years  there  have  been  only  two  crop  failures 
(1895  and  1900);  but  the  plot  required  seeding  only  five  times 
during  the  first  twenty  years  (1854,  1860,  1865,  1868,  and  1871), 
whereas  since  1874  it  has  been  seeded  or  reseeded  almost  every 
year,  and  sometimes  two  or  three  seedings  in  one  year  have  been 
required  to  secure  a  stand.  Late  yields  of  dry  matter  are:  2887 


4o8    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

pounds  in  1901,  1169  pounds  in  1902,  and  1589  pounds  in  1903; 
and  Hall's  book  contains  the  following: 

"In  March,  1897,  and  in  July,  1899, a^  the  plants  were  removed  by  hand,  burnt 
and  their  ashes  returned,  and  the  soil  was  carefully  picked  over  by  hand  for 
the  Sclerotia  of*the  fungus,  Sclerotinia  trifoliorum,  many  of  which  were  found. 
The  soil  was  also  dressed  with  carbon  bisulfid  as  a  fungicide,  before  fresh 
seed  was  sown.  In  1903,  which  was  a  favorable  year  for  the  growth  of  clover, 
a  fair  plant  was  obtained  by  reseeding,  and  in  the  spring  of  1904  the  best  crop 
for  many  years  was  cut  from  this  plot." 

Director  Hall  expresses  the  opinion  that  the  fungus  named  is 
not  the  only  cause  of  "  clover  sickness." 

Finally,  it  should  be  understood  that,  while  the  Rothamsted 
field  experiments  have  been  conducted  with  extreme  care,  there 
are  some  possible  sources  of  error,  and  the  Rothamsted  Station 
has  been  very  careful  to  point  these  out  where  they  are  of  probable 
consequence.  Warrington,  in  his  Rothamsted  lectures  (Bulletin 
No.  8,  Office  of  Experiment  Stations,  United  States  Department 
of  Agriculture),  delivered  before  the  Association  of  American  Agri- 
cultural Colleges  and  Experiment  Stations,  in  1891,  under  the  pro- 
visions of  the  Lawes  Agricultural  Trust,  makes  the  following 
statements: 

"The  earlier  experimental  fields  at  Rothamsted  were  not  arranged  as  skill- 
fully as  the  later  ones;  thus,  Broadbalk  wheat  field  has  long,  narrow  plots, 
and  the  influence  of  the  manure  of  neighboring  plots  is  in  some  cases  distinctly 
felt.  The  barley  experiments  in  Hoos  field  are  the  best  laid  out ;  here  the  plots 
are  nearly  square;  they  have  each  an  area  of  one  fifth  of  an  acre." 

(In  the  author's  opinion,  tenth-acre  plots,  2  by  8  rods  or  i  by 
1 6  rods,  or  fifth-acre  plots,  4  by  8  rods  or  2  by  1 6  rods,  are  more 
satisfactory  than  square  plots  for  field  experiments,  because  greater 
uniformity  between  plots  is  thus  secured;  but  in  all  cases  a  pro- 
tecting border  of  at  least  one  fourth  rod  should  completely  surround 
every  plot,  the  same  crops  being  grown  upon  the  border  as  upon 
the  plot  proper.  This  requires  a  half-rod  division  strip  between 
plots,  and  wherever  needed,  an  additional  uncultivated  strip  of 
grass  sod  should  be  left  between  the  plots.) 

On  the  Grass  Park  at  Rothamsted  an  imaginary  line  is  the  only 
division  between  the  plots,  but  the  ground  is  never  broken,  and  the 
fertilizers  are  applied  as  top  dressings  with  exactness  (a  cloth  screen 


A.  D.  HALL,  DIRECTOR  OF  ROTHAMSTED  EXPERIMENT  STATION 

Author  of  "  The  Soil,"  "  Fertilizers  and  Manures  " 


THE   ROTHAMSTED    EXPERIMENTS 


409 


being  placed  on  the  line),  and  Director  Hall  states  that  the  influ- 
ence of  the  fertilizers  can  scarcely  be  detected  six  inches  over  the 
line,  either  in  the  yield  or  in  the  character  of  the  herbage,  despite 
the  exceedingly  marked  differences  that  have  developed  between 
the  plots. 

THE  CHEMISTRY  OF  ROTHAMSTED  FIELD  EXPERIMENTS 

While  much  chemical  work  has  been  carried  on  from  the  begin- 
ning by  the  Rothamsted  Experiment  Station  in  connection  with 
the  field  experimentation,  it  has  been  directed  more  largely  to 
investigations  concerning  the  composition  of  the  crops  produced 
than  to  soil  analyses.  From  most  of  the  fields  few  soil  analyses 
have  been  reported;  but  in  the  case  of  Broadbalk  field  some  very 
complete  and  thorough  investigations  have  been  made  of  several 
plots.  The  results  are  briefly  summarized  in  Table  73. 

The  soil  samples  upon  whose  analysis  the  data  in  Table  73  are 
chiefly  based  were  collected  in  1893,  fifty  years  from  the  beginning 
of  definite  plot  experiments  on  Broadbalk  field,  although  on  several 
plots  the  final  systems  of  treatment  were  not  fully  settled  until 
1852.  For  this  reason  the  average  yields  are  given  for  the  forty- 
two  years,  1852  to  1893,  but  tne  plant  food  removed  and  applied 
is  computed  for  the  fifty  years;  and,  in  the  main,  estimation  of 
plant  food  removed  is  based  upon  the  analysis  of  the  actual  crops 
harvested. 

In  computing  from  percentages  found  by  analysis  to  pounds 
per  acre,  Doctor  Dyer  has  used  as  the  weight  of  fine  dry  soil  per 
acre  2,590,000  pounds  for  the  first  9  inches,  2,670,000  pounds  for 
the  second,  and  2,790,000  pounds  for  the  third  9  inches.  The  cor- 
responding weights,  including  stones,  are  3,120,000,  3,040,000,  and 
3,000,000  in  round  numbers.  (For  the  common  silt  loam  soils  of 
Illinois,  we  have  found  300,000  pounds  per  acre-inch  to  be  practi- 
cally correct.  This  would  correspond  to  2,700,000  pounds  per  acre 
for  a  9-inch  stratum,  or  2  million  pounds  for  a  6|-inch  stratum.) 

In  considering  the  composition  of  the  soils  represented  in  Table 
73,  it  should  be  kept  in  mind  that  the  nitrogen  reported  is  total, 
while  the  phosphorus  and  potassium  are  the  portions  soluble  in 
strong  acid.  In  the  case  of  phosphorus,  this  usually  represents 


4io     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

nearly  the  total,  but  in  different  soils  it  may  vary  from  the  total 
to  as  low  as  75  per  cent  of  the  total;  while  only  from  15  per  cent 
to  30  per  cent  of  the  total  potassium  is  acid  soluble,  although  in 
some  abnormal  soils,  as  certain  peaty  soils,  it  may  reach  60  per 
cent  or  more  of  the  total.  Potassium  varies  greatly  in  this  respect 
at  different  depths  in  the  same  field.  Thus,  on  the  gray  silt  loam 
prairie  of  the  lower  Illinoisan  glaciation  the  percentage  of  the  total 
potassium  that  is  soluble  in  hydrochloric  acid  (specific  gravity 
1.115),  during  ten  hours'  digestion  at  the  temperature  of  boiling 
water,  varies  from  as  low  as  14  per  cent  in  the  surface  soil  to  as 
high  as  38  per  cent  in  the  subsoil  of  the  same  field. 

Because  of  these  facts  the  determinations  of  potassium  reported 
in  Table  73  must  not  be  considered  as  the  basis  for  any  final  con- 
clusions, but  the  phosphorus  data  must  be  approximately  correct, 
and  the  results  for  nitrogen  are  practically  exact,  except  for  pos- 
sible variation  (from  the  field  average)  of  the  samples  of  soil  col- 
lected. The  data  are  all  reported  for  9-inch  strata  of  soil,  corre- 
sponding to  the  depths  to  which  the  samples  were  taken. 

Table  73  contains  much  information,  but  it  is  self-explanatory. 
Thus,  plot  7,  which  has  received  both  ammonia  and  the  regular 
minerals  (as  more  fully  explained  in  the  previous  pages),  produced 
an  average  yield  of  32.8  bushels  of  wheat  and  3668  pounds  of  straw, 
and  2450  pounds  of  nitrogen,  482  pounds  of  phosphorus,  and  2117 
pounds  of  potassium  were  removed  in  the  crops  during  the  fifty 
years;  while  there  were  applied  4300  pounds  of  nitrogen,  1336 
pounds  of  phosphorus,  and  4181  pounds  of  potassium.  The  appli- 
cations have  been  nearly  double  or  more  than  double  the  amounts 
removed. 

If  we  compare  plots  7  and  3,  we  find  in  the  first  9  inches  about 
23  per  cent  more  nitrogen,  71  per  cent  more  phosphorus,  and  19 
per  cent  more  potassium  in  plot  7  than  in  the  unfertilized  plot  3. 
On  the  other  hand,  in  the  lower  strata,  plot  7  contains  distinctly 
less  phosphorus  than  plot  3  or  4,  but  this  difference  is  much  less 
marked  if  plots  12,  13,  and  14  be  considered.  The  variations  in 
the  lower  strata  are  too  great  to  draw  conclusions  from  any  one 
plot,  and  this  is  more  especially  true  as  regards  potassium. 

In  the  lower  part  of  Table  73  are  recorded  some  average  results 
that  should  be  more  significant,  at  least  for  nitrogen  and  phos- 


THE   ROTHAMSTED    EXPERIMENTS 


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SOIL  TREATMENT  APPLIED  EVERY  YEAR 
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Amm.  salts  and  phosphate  .  . 
Amm.  salts,  phos.,  and  sodium  . 
Amm.  salts,  phos.,  and  potassiui 
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Farm  manure  (15.7  tons)  .  . 
Unfertilized  
Unfertilized  since  1852  .  . 

Minerals  (P,  K,  Mg,  Ca,  Na, 
Amm.  salts  and  minerals 
Ammonium  salts  .  .  .  . 
Amm.  salts  since  1850  .  . 

Average  of  plots  receiving  .  . 
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4i2     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

phorus.  The  line  marked  "  average  of  plots  receiving  "  includes 
the  average  of  plots  7  to  14  for  nitrogen,  of  plots  5,  7,  and  n  to  14 
for  phosphorus,  and  of  plots  5,  7,  and  13  for  potassium;  while 
in  the  next  line  are  given  the  averages  for  the  plots  as  indicated 
(*)  for  the  respective  elements.  By  subtraction  we  find  the  excess 
or  deficiency  (  — ).  The  difference  between  the  sum  of  the  ex- 
cesses found  in  the  three  soil  strata  and  the  balance  with  respect 
to  applications  and  removal  in  crops  gives  us  the  apparent  loss  in 
50  years  of  the  respective  elements,  and  indicates  an  annual  loss 
per  acre  of  55  pounds  of  nitrogen,  8|-  pounds  of  phosphorus,  and 
59  pounds  of  potassium,  —  losses  besides  those  which  are  ac- 
counted for  in  the  crops  removed.  In  terms  of  plant  food 
applied,  these  losses  amount  to  63  per  cent  of  the  nitrogen,  to  31 
per  cent  of  the  phosphorus,  and  to  69  per  cent  of  the  potassium. 

There  are  two  principal  ways  in  which  plant  food  may  be  lost 
from  the  surface  soil,  aside  from  removal  in  crops;  namely,  by 
leaching  and  by  erosion  (including  erosion  by  wind  action  as  well 
as  by  water).  In  addition,  some  mechanical  mixing  of  surface  and 
subsoil  may  occur,  because  of  burrowing  animals  and  insects, 
soil  cracking,  etc.,  and  losses  of  nitrogen  by  dentrification  are 
possible,  though  not  probable  to  any  important  extent  under 
normal  conditions. 

In  Table  74  is  recorded  the  average  composition  of  waters  col- 
lected from  the  tile  drains  of  Broadbalk  field  during  the  years 
1866, 1867, 1868,  and  1869.  These  averages  represent  the  mean  of 
a  large  number  of  analyses  made  by  Doctor  Augustus  Voelcker. 
The  results  are  given  in  Table  74  on  the  basis  of  3  million  pounds 
of  water,  which  corresponds  to  a  drainage  of  13^-  inches  per  acre, 
which  is  less  than  the  average  annual  drainage  (14.73  inches) 
from  the  uncropped  bare  soil  of  the  Rothamsted  drain  gauge  (see 
Table  65),  and  more  than  Dyer's  estimate  (10  inches)  for  the  ordi- 
nary cropped  soils  at  Rothamsted,  but  probably  not  more  than  the 
average  for  the  cropped  soils  of  central  United  States.  The  actual 
amounts  found  in  pounds  per  million  of  drainage  water  will  be 
secured  by  dividing  these  data  by  three. 

Some  apparent  relationships  may  be  noted  between  the  appli- 
cations and  losses  of  certain  elements,  and  also  between  certain 
elements  in  the  drainage  water,  such  as  calcium  and  sulfur,  but 


THE   ROTHAMSTED    EXPERIMENTS 


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414     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

the  points  of  chief  interest  are  that  from  the  four  or  five  best 
yielding  plots  the  annual  losses  per  acre  are  probably  not  more 
than  50  pounds  of  nitrogen,  i^  pounds  of  phosphorus,  and  7  pounds 
of  potassium.  Dyer  assumes  an  average  drainage  of  10  inches  per 
annum  for  Rothamsted,  which  would  reduce  these  figures  by  one 
fourth,  but  he  also  suggests  that  the  losses  in  drainage  are  probably 
greater  now  than  they  were  in  1866-1869. 

While  the  drainage  certainly  accounts  for  most  of  the  loss  of 
nitrogen,  there  remains  not  accounted  for  an  annual  loss  of  about 
7  pounds  of  phosphorus  and  50  pounds  of  potassium  per  acre. 
Dyer  suggests  that  these  losses  are  to  be  accounted  for  by  descent 
into  the  subsoil.  The  data  for  potassium,  representing  the  "  acid- 
soluble"  only,  are  too  uncertain  to  warrant  any  conclusion.  In 
the  author's  opinion  it  is  not  improbable  that  some  of  the  potas- 
sium, applied  as  soluble  potassium  sulfate,  may  have  reacted  with 
silicates  and  formed  compounds  that  are  not  dissolved  by  strong 
acid.  This  seems  less  doubtful  when  we  consider  the  proper- 
ties of  cement,  and  the  changes  that  occur  even  in  a  short  time 
in  the  "  setting  "  of  that  material. 

The  data  afford  practically  no  evidence  for  the  "descent  into 
the  subsoil  of  either  phosphorus  or  potassium.  The  phosphorus 
determinations  so  nearly  represent  the  total  amounts  that  they 
serve  satisfactorily  for  general  computations,  and  as  an  average 
they  show  less  phosphorus  in  the  subsoil  of  the  plots  where  phos- 
phorus has  been  applied,  although  plots  5  and  14  are  exceptions. 

At  least  most  of  the  unused  phosphorus  remains  in  the  plowed 
soil.  Thus  plots  4  and  5  have  produced  almost  the  same  average 
yields,  and  plot  5  contains  1121  pounds  more  phosphorus  in  the 
first  9  inches,  but  only  n  pounds  more  in  the  second  depth,  than 
plot  4.  The  third  depth  shows  a  different  relation,  but  this  is 
reversed  in  the  case  of  plots  lob  and  n,  whose  average  yields  are 
not  markedly  different. 

With  2250  pounds  of  phosphorus  in  the  surface  9  inches,  it 
would  require  about  one  inch  of  erosion  in  35  years  to  account  for 
an  annual  loss  of  7  pounds  of  phosphorus.  This  would  also  ac- 
count for  10  pounds  additional  loss  in  nitrogen,  and  it  seems  the 
most  probable  explanation.  Land  that  has  sufficient  slope  to 
provide  any  surface  drainage  will  suffer  some  erosion  if  such  drain- 


THE    ROTHAMSTED    EXPERIMENTS  415 

age  occurs  when  the  land  is  not  covered  with  vegetation.  When- 
ever roily  water  leaves  a  field,  some  soil  goes  with  it;  and  the  loss 
of  a  tenth  of  an  inch  in  three  or  four  years  is  not  improbable,  even 
for  nearly  level  land,  if  annually  cultivated,  especially  if  torrential 
rains  sometimes  occur  (see  record  of  Barn  field) 

Whether  one  assumes  10  inches  or  13  j  inches  of  drainage,  there 
is  some  degree  of  correlation  between  the  computed  calcium 
carbonate  equivalent  to  the  calcium  found  in  the  drainage  water,  as 
shown  in  Table  74,  and  the  loss  of  calcium  carbonate  from  the  sur- 
face soil  of  Broadbalk  field,  as  recorded  in  Table  27.  While  there 
are  marked  discrepancies,  both  methods  agree  that,  as  an  average, 
more  calcium  is  removed  from  the  plots  receiving  ammonium 
salts. 

Analyses  made  of  surface  soil  from  the  barley  plots  on  Hoos 
field  in  1889  show  in  2  million  pounds  of  soil  960  pounds  of  phos- 
phorus as  an  average  in  the  8  plots  receiving  no  phosphorus,  1560 
pounds  as  an  average  in  the  8  plots  receiving  acid  phosphate  with- 
out rape  cake,  1900  pounds  as  an  average  in  the  2  plots  receiving 
acid  phosphate  and  rape  cake,  and  1540  pounds  in  the  farm  manure 
plot  (7-2). 

Table  75  shows  the  nitrogen  content  of  the  surface  9  inches  of 
the  different  plots  on  the  Agdell  rotation  field. 

From  the  data  thus  far  reported,  the  nitrogen  content  of  the  soil 
on  Agdell  field  appears  to  be  decreasing  about  10  pounds  a  year, 
except  on  the  legume  plots  which  receive  rape  cake  and  ammonium 
salts,  where  an  increase  is  shown  on  the  "  fed  "  plot  amounting  to 
212  pounds  in  16  years.  While  the  individual  variations  are  great, 
the  results  indicate  a  slightly  larger  loss  of  nitrogen  in  the  legume 
rotation  than  with  fallow,  but  where  nitrogen  is  applied,  the  op- 
posite is  shown. 

The  factors  of  erosion  and  deposition  and  of  difficulty  in  securing 
samples  (by  the  method  used)  which  fairly  represent  the  average 
of  the  plot  are  sufficient  to  account  for  any  of  the  changes  indi- 
cated by  these  analytical  data;  and  it  may  be  stated  that  the  to- 
pography of  Agdell  field  suggests  the  possible  influence  of  such 
factors.  On  the  other  hand,  the  indicated  gain  of  180  pounds  of 
nitrogen  per  acre  during  seven  years  with  the  legume  rotation  on 
the  unfertilized  land,  with  all  crops  removed,  has  actually  been 


4i 6    INVESTIGATION   BY   CULTURE    EXPERIMENTS 


TABLE  75.   AGDELL  ROTATION  FIELD,  ROTHAMSTED 
Nitrogen  in  Surface  9  inches;   Pounds  per  Acre 


SYSTEMS  AND  SOIL  TREATMENT 

Nov.,  1867 
(After 
Wheat) 

OCT.,  1874 
(After  Clover 
or  Fallow) 

NOV.-JAN., 
1883-1884 

(After  Wheat) 

Legume,  unfertilized,  turnips  removed 
Legume,  unfertilized,  turnips  fed  off   . 
Legume,  phosphorus,  turnips  removed 
Legume,  phosphorus,  turnips  fed  off  . 

3127 
3IJ3 
3185 
33^2 

33°  7 
2849 
2978 
317° 

3*39 
2892 
2897 
3110 

Average  of  four  plots    

?l8S 

3076 

3OIO 

Loss  in  1  6  years     

17s 

Fallow,  unfertilized,  turnips  removed  . 
Fallow,  unfertilized,  turnips  fed  off 
Fallow,  phosphorus,  turnips  removed  . 
Fallow,  phosphorus,  turnips  fed  off 

3127 

2959 
2938 
2976 

3XI3 
2976 

2753 
2702 

2952 
2724 
2786 
2947 

Average  of  four  plots     

3OOO 

2842 

28  =n 

Loss  in  1  6  vears     

147 

Plots  receiving  Minerals,  Rape  Cake,  and  Ammonium  Salts 


Legume,  turnips  removed  

30  ?8 

-2006 

-2QI2 

Legume,  turnips  fed  off     

3T94 

3293 

3408 

Average  of  two  plots      .     .          ... 

-2116 

2IQC 

•22IO 

Gain  in  16  years     

(04) 

Fallow,  turnips  removed     

3OIO 

2887 

2918 

Fallow,  turnips  fed  off  

•2107 

2Q4O 

2986 

Average  of  two  plots     

^IO4 

2QI4 

2Q1T2 

Loss  in  16  years     

1^2 

cited  by  a  writer  for  the  agricultural  press  in  support  of  the  teach- 
ing that  crop  rotation  will  maintain  the  fertility  of  the  soil. 

Probably  no  information  could  now  be  furnished  by  the  Roth- 
amsted  Station  that  would  be  of  greater  interest  to  the  agricul- 
tural world  than  the  changes  that  have  occurred  in  the  nitrogen 
content  of  the  Agdell  plots  since  1883. 

In  Tables  76  and  77  are  recorded  the  average  composition  of  the 
Agdell  crops  (except  barley  not  reported)  and  the  Park  hay,  re- 


THE    ROTHAMSTED    EXPERIMENTS 


417. 


spectively.  The  data  are  given  in  pounds  per  acre  removed  in 
the  actual  crops  grown,  —  on  the  plots  receiving  both  minerals  and 
nitrogen  in  case  of  the  Agdell  field. 

TABLE  76.  AVERAGE  COMPOSITION  OF  CROPS   GROWN  ON  AGDELL  FIELD 
Pounds  per  Acre  actually  removed  in  the  Crops  Harvested 


CROPS  ANALYZED 

CROP 
YIELDS 
(Approx.) 

NITRO- 
GEN 
(N) 

PHOS- 
PHO- 
RUS 
(P) 

PO- 
TAS- 
SIUM 
(K) 

MAG- 
NE- 
SIUM 
(Mg) 

CAL- 
CIUM 
(Ca) 

SUL- 
FUR 
(S) 

SODI- 
UM 
(Na) 

CHLO- 

RIN 

(Cl) 

Wheat,  grain  .     . 
Wheat,  straw 
Wheat  crop     .     . 

Swede  turnips 
Turnip  leaves 
Turnip  crop    .     . 

Beans,  grain    .     . 
Bean  straw      .     . 
Bean  crop  .     .     . 

Clover,  first  crop 
Clover,  second  crop 
Clover,  both  crops 

30  bu. 
1.9  T. 

28.3 
13-4 

6.8 
2.1 

8.5 

21.8 

2.1 
2.O 

•7 
6.4 

.2 
2.1 

.04 
.62 

.OI 
3.28 

41.7 

75-5 
18.5 

8.9 

8.6 
1.9 

30-3 

65-7 
11.9 

4.1 

3-7 

•5 

7-i 

15.6 
9.1 

2-3 

10-4 
2-3 

.66 

7-5 
•  7 

3-29 

5-2 

5-5 

i6T. 

2T. 

94.0 

49.6 
14.0 

10.5 

S-o 
•9 

77.6 

12.6 

5-8 

4-2 

i-5 
1.6 

24.7 

i-5 
i7-5 

12.7 
1.0 

I.I 

8.2 

.6 
9-3 

10:7 

•9 

2.2 

23  bu. 
.9T. 

63.6 

i°33 
56.0 

5-9 

7-8 
4-5 

18.4 

58.6 
26.5 

3-1 

ii.  6 
5-9 

19.0 

92-5 
36.8 

2.1 

3-7 

2.1 

9-9 

1.9 
.8 

3-i 

ii  7 
6.1 

3-o  T. 

159-3 

12.3 

85.1 

17-5 

129-3 

5-8 

2-7 

17.8 

The  results  for  wheat  are  the  average  of  the  eight  crops  grown 
from  1850  to  1879;  for  turnips,  the  average  is  for  three  crops 
(1864,  1872,  and  1876);  for  beans,  six  crops  (1854  to  1870  and 
1878) ;  and  the  clover  data  are  averages  of  1850  and  1874  for  the 
first  and  second  crops. 

In  Table  77  the  data  represent,  as  a  rule,  in  pounds  removed  per 
acre  per  annum,  the  averages  for  the  18  years,  1856  to  1873  (first 
crops  only). 

This  mass  of  data  concerning  actual  results  with  mixed  grasses 
is  especially  valuable  for  the  use  of  the  analytical  mind.  A  cur- 
sory examination  will  show  that,  within  the  groups,  the  total 
yield  of  organic  matter  correlates  better  with  the  nitrogen  and 
phosphorus  removed  than  with  most  other  constituents,  while 
the  amount  of  potassium  removed  seems  to  be  controlled  by  the 


4i8    INVESTIGATION   BY   CULTURE   EXPERIMENTS 


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TABLE  77.  COMPOSI 
Pounds  removed  per  Acr 

Son,  TREATMENT  APPLIED  PER  At 
(Except  as  Notec 

Group  1.  Manure  and  A 
(Manure,  amm.  salts,  8  years)  ; 
10  years  
(Manure  8  years)  ;  then  unfertil 
Unfertilized  

Group  #.  Mineral  Ft 
Minerals,  including  K,  6  years 
Minerals,  excluding  K,  12  years 

.^ 

be 
O  <n 

•§,2 

T3    U 

Group  8.  Nitrogen  F 
Ammonium  salts  
Sodium  nitrate  
Sodium  nitrate  

Group  4-  Minerals  and 
Amm.  salts  and  minerals,  inclut 
Amm.  salts  and  minerals,  exclu 

Ammonium  salts,  13  years  . 
Minerals,  5  years  .... 

Amm.  salts  and  acid  phosphate 

Amm.  salts  and  minerals  .  .  . 
Amm.  salts  and  minerals  .  . 
Amm.  salts,  minerals  (including 
Amm.  salts,  minerals,  and  straw 

JNltrate  and  minerals  .  .  .  . 
Nitrate  and  minerals  .  .  . 

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THE    ROTHAMSTED    EXPERIMENTS 


419 


amount  applied  as  much  or  more  than  by  the  amount  of  crop  har- 
vested. Thus  the  organic  matter  from  plot  7  is  1.54  times  that 
from  plot  4-1;  while  the  corresponding  ratios  are  1.62  for  phos- 
phorus and  1.66  for  nitrogen,  but  3.19  for  potassium.  Quite 
similar  results  are  secured  by  comparing  plots  4-2  and  9,  the  ratios 
being  1.56  for  organic  matter,  1.28  for  nitrogen,  1.34  for  phosphorus, 
and  3.96  for  potassium. 

These  facts  seem  to  harmonize  with  the  suggestion  previously 
made  that  some  of  the  apparent  effect  on  the  yield  of  hay,  of  the 
potassium  and  other  alkali  salts,  is  associated  with  their  power  to 
take  phosphorus  (in  part  from  the  surface,  where  applied  in  top 
dressings)  and  deliver  it  to  the  root  system  of  the  plant.  Another 
influence  of  possible  importance  is  the  tendency  of  the  alkali  salts 
to  reduce  or  prevent  soil  acidity.  Of  course,  potassium  has  some 
value  for  its  own  sake  under  certain  conditions,  as  clearly  shown 
in  the  previous  and  subsequent  pages  (see  especially  the  mangel- 
wurzel  data). 

With  the  great  differences  that  have  developed  in  the  character 
of  the  herbage  on  the  different  plots,  especially  in  different  groups, 
direct  comparisons  must  involve  several  factors;  and  coincidence 
or  indirect  correlation  may  easily  be  mistaken  for  direct  causal 
relationship.  Thus,  compared  with  plot  14,  we  would  assume  that 
potassium  must  be  the  limiting  element  on  plot  4-2 ;  and  possibly 
such  is  the  case,  but  reference  to  plots  7  and  10  show  that  other 
factors  are  also  involved. 

LATE  CROP  YIELDS  PER  ACRE  ON  AGDELL  FIELD,  ROTHAMSTED 


SOIL  TREATMENT    .     . 

UNFERTILIZED 

MINERALS 

MINERALS  AND  NITROGEN 

Syste 

m  

Legume 

Fallow 

Legume 

Fallow 

Legume 

Fallow 

1908 

Turnips,  roots,  Ib. 
Leaves,  Ib.  .    . 

7<7 
470 

2419 

'747 

26410 

4838 

20048 
33i5 

35,68 
15568 

44285 
M3i4 

1909 

igiO 

Barley,  grain,  bu. 
Straw,  Ib.     .    . 

1263 

it.  4 
"34 

22.1 
1892 

i7-4 
1426 

33-4 
2661 

26.8 
2091 

Clover,  hay,  Ib.    . 

1949 

7190 

8590 

I9II 

Wheat,  grain,  bu. 
Straw,  Ib.     .     . 

24.5 
2400 

23-9 
2290 

37-8 
3753 

3'-9 
3205 

38.0 
3638 

33-3 
3280 

CHAPTER  XX 

PENNSYLVANIA    FIELD    EXPERIMENTS 

IN  1882  the  Pennsylvania  Agricultural  Experiment  Station 
began,  at  State  College,  the  oldest  extensive  field  experiments  now 
in  progress  in  America.  They  include  four  separate  fields,  each 
of  which  contains  36  eighth-acre  plots,  or  144  different  plots  in  all. 
A  4-year  rotation  is  practiced,  consisting  of  corn,  oats,  wheat, 
and  hay  (mixed  clover  and  timothy  seeded  on  the  wheat  land  in 
the  early  spring) ,  every  crop  being  represented  every  year  (ex- 
cepting the  hay  crop  in  1882).  The  land  is  quite  undulating,  but 
the  individual  plots  are  separated  by  a  permanent  strip  of  grass 
sod  or  turf  about  two  or  three  feet  wide,  which  practically  pre- 
vents surface  washing  from  one  plot  to  another,  and  in  but  few 
cases  is  there  evidence  of  soil  washing  on  the  fields.  The  plots 
are  about  i^  rods  wide  by  16  rods  long. 

The  soil  consists  largely  of  a  silty  clay  loam,  and  contains  perhaps 
10  per  cent  of  small  angular  rock  fragments,  chiefly  of  chert. 
While  this  field  had  been  treated  with  lime  some  years  before  the 
beginning  of  these  experiments,  recent  examination  has  shown  that 
the  soil  is  more  or  less  acid.  Even  where  sodium  nitrate  has  been 
applied,  acidity  is  found  as  a  rule,  notwithstanding  the  tendency 
of  sodium  nitrate  to  neutralize  soil  acidity,  much  of  the  sodium 
being  left  in  the  soil  when  the  nitrogen  is  taken  up  by  plants. 
Where  ammonium  sulfate  has  been  used,  especially  where  heavy 
applications  are  made,  the  soil  is  very  much  more  acid;  and  on 
such  plots  the  red  sorrel  (Rumex  acetocelld)  is  becoming  a  pest,  and 
a  good  stand  of  clover  is  not  secured  as  a  rule.  As  hereinbefore 
stated,  the  average  soil  of  this  field  contains  2320  pounds  of  nitro- 
gen, 1080  pounds  of  acid-soluble  phosphorus,  and  50,700  pounds 
of  total  potassium,  in  2  million  pounds  of  the  surface  soil. 

420 


PENNSYLVANIA   FIELD   EXPERIMENTS  421 

The  following  statements  are  made  in  the  Pennsylvania  Report 
for  1901-1902,  pages  195-197: 

"It  should  be  stated  that  this  soil  has  been  formed  in  place  on  the  underly- 
ing rock.  The  rock  is  in  some  instances  but  a  few  feet  below  the  surface  of  the 
ground.  While  the  surface  soil  is  fairly  uniform  in  fertility  and  in  depth,  the 
subsoil  varies  greatly  as  to  depth.  This  soil  has  good  natural  underdrainage, 
and  contains  a  fair  supply  of  humus.  While  the  soil  is  a  somewhat  stiff  clay 
loam,  the  natural  drainage  is  entirely  sufficient  to  carry  off  excessive  moisture, 
even  in  time  of  heavy  rainfall." 

"The  cultivation  given  this  series  of  plots  has  been  similar  to  that  given  to 
ordinary  field  crops  under  good  cultural  conditions." 

"The  operations  of  harvesting  have  been  performed  as  uniformly  as  possible 
for  all  plots,  in  order  that  any  variation  of  the  yield  might  not  be  due  in  any  way 
to  the  difference  in  the  manner  of  handling  the  crops  when  matured. 

"Corn.  The  corn  was  cut  by  hand  and  placed  in  medium-sized  shocks  to 
cure.  From  the  shocks  it  was  husked  in  the  field,  and  the  ears  of  corn  weighed 
and  the  yield  of  stalks  weighed  when  sufficiently  cured  to  store  in  the  barn  with- 
out danger  from  heating. 

"Oals  and  Wheat.  The  oats  and  wheat  have  been  cut  with  a  twine  binder, 
and  the  bundles  placed  in  shocks  on  the  plots,  where  they  remained  until  suffi- 
ciently dry  for  threshing.  They  were  then  drawn  to  the  barn,  weighed,  threshed, 
and  the  weight  of  the  grain  deducted  from  the  total  weight  to  ascertain  the 
weight  of  straw  and  chaff,  the  difference  being  the  credited  weight  of  straw. 

" Hay.  The  grass  (clover  and  timothy  mixed)  has  been  cut  with  a  mowing 
machine  and  given  the  same  treatment  as  found  practical  to  give  grass  and  hay 
on  the  College  and  Experiment  Station  farms.  When  the  forage  was  suffi- 
ciently cured  to  store  in  the  barns  without  danger  from  fermentation,  the  hay 
was  drawn  to  the  barn  and  weighed." 

While  the  three  grain  crops  were  grown  in  1882  and  all  crops  in 
1883,  the  full  fertilizer  treatment  for  the  four  years  was  not  received 
by  some  plots  until  1885,  and  consequently  the  results  for  the  first 
three  years  must  be  considered  as  preliminary.  The  fertilizer 
applications  are  made  only  in  alternate  years,  for  corn  and  wheat 
(excepting  the  caustic  lime,  which  is  applied  but  once  in  four  years, 
for  corn) . 

The  application  for  nitrogen  is  at  three  different  rates,  24,  48, 
and  72  pounds  per  acre  in  alternate  years,  or  48,  96,  and  144  for 
each  rotation;  and  three  different  forms  of  nitrogen  are  used, 
dried  blood,  sodium  nitrate,  and  ammonium  sulfate.  For  the  four 
years  the  potassium  applied  amounts  to  166  pounds  (always  in 
potassium  chlorid,  so-called  "  muriate  "  of  potash),  and  the  phos- 


422     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

phorus  amounts  to  42  pounds  (usually  in  dissolved  bone  black). 
On  two  plots  (12  and  35)  the  phosphorus  (42  pounds)  is  applied  in 
the  form  of  ground  bone,  which  also  supplies  10  pounds  additional 
nitrogen. 

Farm  manure  (commonly  called  "  yard  manure,"  but  sometimes 
"  barn  manure,"  in  the  Pennsylvania  Reports)  was  applied  at 
three  different  rates,  12,  16,  and  20  tons  per  acre  (one  half  for  corn 
and  the  other  half  for  wheat),  and  in  addition  12  tons  were  applied 
on  one  of  the  caustic  lime  plots  (No.  22).  No  analysis  seems  to 
have  been  made  of  the  manure,  but  the  Pennsylvania  Station  has 
at  times  adopted  an  average  published  by  the  United  States  De- 
partment of  Agriculture,  representing  one  ton  to  contain  9.8  pounds 
of  nitrogen,  2.8  pounds  of  phosphorus,  and  7.1  pounds  of  potas- 
sium, —  figures  that  are  not  far  from  the  general  average  of  yard 
manure  (10,  3,  8).  Probably  the  20  tons  of  manure  carry  a  third 
more  nitrogen  and  phosphorus,  and  nearly  the  same  amount  of 
potassium,  as  the  heaviest  fertilizer  application  (144  Ib.  N,  42  Ib.  P, 
and  166  Ib.  K). 

The  other  applications  for  each  four  years  include  640  pounds 
of  land-plaster  (gypsum) ,  4  tons  of  ground  limestone,  and  2  tons  of 
caustic  lime,  weighed  as  calcium  oxid  and  applied  after  being  water- 
slacked. 

In  addition  there  are  five  plots  in  each  series  that  have  received 
no  fertilizer  since  1882,  but  one  of  these  (No.  8)  is  reported  to  have 
received  annual  applications  of  farm  manure  during  the  10  years 
previous  to  1882. 

The  numbering  of  plots  and  the  treatment  applied  for  one  series 
of  36  plots  is  the  same  as  for  every  other  series.  By  using  four 
different  series,  four  times  as  much  data  are  secured  during  a  given 
number  of  years  as  could  be  secured  from  one  series.  Thus,  dur- 
ing the  24  years  (1885  to  1908),  there  have  been  24  crops  of  corn, 
24  of  oats,  24  of  wheat,  and  24  of  hay,  with  every  different  kind  of 
treatment;  whereas,  during  61  years,  on  Agdell  field  at  Rotham- 
sted  there  have  been  harvested  only  15  crops  of  turnips,  15  of 
barley,  15  of  legumes,  and  15  of  wheat  (the  turnips  having  failed 
one  year).  Of  course  the  effect  of  60  years'  cropping  cannot  be 
secured  in  27  years,  but  the  Pennsylvania  system  must  give  more 
trustworthy  results  for  the  like  number  of  years. 


PENNSYLVANIA   FIELD    EXPERIMENTS 


423 


TABLE  78.     PENNSYLVANIA  EXPERIMENTS:  FOUR -YEAR  ROTATION 
Records  per  Acre  for  Six  Complete  Rotations,  1885  to  1908 


TREATMENT  FOR  EACH 
FOUR  YEARS  l 

AVERAGE  OF 
24  YEARS 

FROM  FOUR  ACRES 

1 

c 

04 

Important 
Elements 
Applied 

Ni- 
tro- 
gen 
per 
Acre 
(Lb.) 

Form  of  Nitro- 
gen Applied 

Corn 
Av. 
Bu. 
per 
Acre 

Oats 
Av. 
Bu. 
per 
Acre 

Wheat 
Av. 
Bu. 
per 
Acre 

Hav 
Av.' 

Lb. 
per 
Acre 

Value 

of  the 
Four 
Crops 

Value 
if  Un- 
fertil- 
ized 

Value 
of  In- 
crease 

Cost 
of 
Treat- 
ment 

Profit 
or 
(-Loss) 

I 

a 
3 

_± 

S 
6 

1 
8 

None   .    . 

N  (48  Ib.) 
P  (42  Ib.) 
K(i66!b.) 

29.2 
33-2 
40.4 
33-1 

27.8 
29.4 
34-9 
31-2 

IO.I 

11.7 
iS-i 

10.  0 

2020 
2170 
3180 
2360 
3610 
2690 
4340 
356o 
438o 
4140 
4220 
4220 
2480 
2400 
4290 
4030 
3660 

831-69 
3S-I4 
44-72 
35-66 

$31-69 
32.12 
32-55 
32-08 

$ 

48 

Dried  blood     . 

3-02 

12.17 
2.68 

7.20 
5-04 
0.96 

(-4.18) 
7-i3 

(           •,    0»^ 

NP      .     . 
NK     .     . 
PK      .     . 

48 
48 

Dried  blood    . 
Dried  blood     . 

42.8 
34-7 
48.4 
45-0 

38.9 
33-5 
40.8 

35-4 
41.9 
42.9 
42.1 
41.1 

18.9 

12.8 

17.7 

15-1 

50.71 
39-23 
54-59 
47-62 

33-41 
33-84 
34.27 
34-70 

17-30 
5-39 
20.32 

12.92 

12.24 
17.16 
15.00 

(?) 

5.06 
(-11.77) 
5.32 

I2.O2 

Manure  for  10  years  prior  to  1882 

9 

10 

ii 

12 

NPK  .     . 
NPK  .    . 
NPK  .    . 
NPK  .    . 

48 
96 
144 
60 

Dried  blood     . 
Dried  blood     . 
Dried  blood     . 
Blood  and  bone 

47-6 
47-4 
48.S 
4--6 

36.2 

20.9 
23.0 
24.6 
20.5 

57-00 
57-98 
59-49 
56.70 

35-13 
35-56 
35-99 
36.42 

21.87 
22.42 
23-50 
20.28 

22.20 
29.40 
36.60 
23.16 

(--33) 
(-6-98) 
(-13.10) 

(-2.88) 

11 
14 
IS 

Land-plaster  (CaSO4),  640  Ib.     . 

30.6 

29-4 
37-8 

39-o 
37-8 

12.  0 

38.32 

36.84 

1.48 

1.  60 

(-.12) 

None  .     . 
PK      .     . 

35-5 
47.8 

49-5 

41.  1 

12.6 
I7.8 
22.S 

20.3 

37-27 
53-40 
56-87 
50.02 

37-27 
37-20 

37-12 
37-05 



16.20 
19-75 
13-87 

15.00 
3.60 
22.20 

1.20 
I6.I5 
(-8-33) 

1  6 

Yard  manure,  12  tons    .... 

*7 

NPK  .     .        48  |  Dried  biood     . 

1  8 

Yard  manure,  16  tons    .... 

46.5 
47.8 
50.1 

48.8 

41.0 
40.1 
40.8 
40.4 

23-7 
22.9 
24.1 
24.8 

42QO 
4120 
4300 
4000 

58.04 
57-15 
59-55 
58.56 

36.97 
36.90 
36.82 
36.75 

21.07 
20.25 
22.73 
21.81 

4.80 
29.40 

6.00 
36.60 

16.27 
(-9-15) 
16.73 

(-14.79) 

10 

NPK  .     .        96  (Dried  blood     . 

20 
91 

Yard  manure,  20  tons  .... 

NPK.     .      144  |  Dried  blood    . 

22 
23 

Lime  (CaO),  2  tons  ;   yard  ma- 
nure, 12  tons     
Lime  (CaO),  2  tons  

Si-4 

27.4 

40.6 
27.2 

22.5 
14.4 

4330 
2440 

58.91 

35-iS 

36-67 
36.60 

22.24 

(-1.45) 

12.60 

Q.OO 

9-64 

(  —  10.45) 

24 

25 

36 

27 

28 

None  .    . 
PK      .    . 
NPKNa  . 
NPKNa  . 
NPKNa  . 

48 
96 

144 

3°-4 
47-5 
49-3 
49-5 
42-6 

30.9 
40.2 
40-3 
41.1 

41-3 
38.6 
39-8 
41.1 

40.3 

13.4 

18.5 

21.9 

23-7 
24-  5 

2410 
4230 
4330 
4370 
4370 

36-52 
54-33 
57.67 
59-36 
60.01 

36.52 
36.74 
36.96 
37-i8 
37-40 

17-59 

20.71 
22.18 

22.  6l 

15.00 
22.20 
29.40 
36.60 

2.59 
(-1-49) 
(-7.22) 
(-13.99) 

Sodium  nitrate 
Sodium  nitrate 
Sodium  nitrate 

29 

30 

31 
3* 

PK      .     . 
NPK  .    . 
NPK  .    . 
NPK  .    . 

48 
96 

144 

42.7 
46.4 
46.9 
40.1 

17.4 

21.6 
23-5 
22-S 

4040 
4020 
3630 
3280 

50.83 
55-36 
56-09 

51-72 

37-62 
37-84 
38.06 
38.28 

13.21 
I7-52 
18.03 
13-44 

15.00 
22.2O 
29.40 
36.60 

(-1-79) 
(-4-68 
(-11-37) 
(-23-16) 

Amm.  sulfate  . 
Amm.  sulfate  . 
Amm.  sulfate  ; 

33 
34 

35 

36 

Land-plaster  (CaSO4),  640  Ib.    . 
Ground  limestone  (CaCO3),  4  ton^ 

3i-5 
34-9 
48.  1 
33-6 

31-2 
32.4 
40.4 
31-1 

I3-I 

IS-S 
21.7 
I4.I 

2570 
2880 
4690 
2730 

37-27 
41-43 
58-36 
39-15 

38-50 
38-72 
38.94 
39-15 

(-1-23) 
2.71 

19.42 

1.60 
6.00 
23.16 

(-2.83) 
(-3-29) 
(-3-74) 

NPK  .     . 

None  .    . 

60 

Blood  and  bone 

1  Where  used,  potassium  is  always  applied  at  the  rate  of  166  Ib.  per  acre  in 
potassium  chlorid,  and  phosphorus  always  at  the  rate  of  42  Ib.  per  acre  in  acid 
bone  black  except  on  plots  12  and  35,  where  ground  bone  is  used.  One  half  of 
the  application  is  made  for  corn  and  the  other  half  for  wheat,  except  the  burnt  lime, 
which  is  all  applied  for  corn. 

In  Table  78  are  recorded  the  average  results  in  actual  yields  of 
corn,  oats,  wheat,  and  hay,  for  the  24  years,  1885  to  1908.  In  order 


424     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

to  eliminate  so  far  as  possible  the  influence  of  seasonal  variation 
in  individual  crops  and  to  simplify  comparison,  the  aggregate  value 
of  the  four  crops  has  been  computed,  so  that  in  all  cases  the  finan- 
cial statement  refers  to  values  for  four  acres.  No  value  is  allowed  for 
the  corn  stover  or  straw,  and  the  prices  used  are  35  cents  a  bushel 
for  corn,  30  cents  for  oats,  70  cents  a  bushel  for  wheat,  and  $3  per 
1000  pounds  for  hay.  While  these  prices  should  be  modified  to  suit 
local  conditions,  they  are  as  high  as  can  safely  be  used  as  a  basis 
for  planning  profitable  systems  in  the  center  of  the  principal  grain- 
growing  section  of  the  United  States,  especially  if  we  must  allow 
for  some  shrinkage  (particularly  in  the  yield  of  hay)  and  for 
occasional  unavoidable  losses  from  damaging  storms. 

In  the  column  headed  "  Value  of  the  four  crops,"  it  will  be  seen 
that  the  figures  range  from  $31.69  (plot  i,  untreated)  to  $60.01 
(plot  28,  receiving  phosphorus,  potassium,  and  the  heaviest  appli- 
cation of  sodium  nitrate).  The  four  untreated  plots  show  $31.69, 
$37.27,  $36.52,  and  $39.15,  making  a  very  considerable  variation; 
and  the  problem  presents  itself,  How  shall  we  determine  the  increase 
produced  by  the  different  kinds  of  treatment?  Manifestly,  we  must 
adopt  some  method  of  estimating  what  would  have  been  the  yield 
of  the  fertilized  plots  if  they  had  not  been  fertilized.  The  average 
of  the  four  untreated  plots  would  be  the  most  satisfactory  under 
some  conditions,  but  plainly  this  is  not  correct  for  these  conditions, 
because  this  would  show  an  injurious  effect  from  the  nitrogen 
alone,  whereas  positive  and  very  appreciable  gains  are  produced 
in  every  crop  on  plot  2  in  comparison  with  the  immediately  ad- 
joining unfertilized  plot  (No.  i).  In  the  absence  of  specific  objec- 
tions it  seems  best  to  assume  that  the  productive  power  of  the  land, 
if  unfertilized,  would  vary  in  uniform  graduation  from  one  check 
plot  to  the  next,  and  the  figures  given  in  the  column  headed 
"  Value  if  unfertilized  "  are  computed  on  this  basis.  While  this 
seems  fair  to  plots  near  No.  i,  a  comparison  of  duplicate  plots  shows 
some  marked  differences  in  "  Value  of  increase,"  especially  be- 
tween plots  9  ($21.87)  and  I7  ($13-87),  and  between  7  ($20.32)  and 
29  ($13.21),  although  in  the  main  the  duplication  is  sufficiently 
harmonious  to  justify  full  confidence  in  important  average  results. 
Thus,  the  four  plots  receiving  phosphorus  and  potassium  show 
"Value  of  increase"  amounting  to  $20.32,  $16.20,  $17.59,  and 


PENNSYLVANIA   FIELD    EXPERIMENTS  425 

$13.21  (average  $16.83);  and  with  48  pounds  of  nitrogen  in  addi- 
tion, the  increase  is  $12.87,  ^S-Sy,  $20.71,  and  $17.52  (average 
$18.49).  Here  we  have  an  average  increase  of  $1.66  resulting  from 
the  application  of  $7.20  in  48  pounds  of  nitrogen.  Further  addition 
of  nitrogen  produces  some  additional  increases,  but  always  far 
below  the  cost  of  the  nitrogen  applied. 

After  subtracting  the  cost  of  treatment  (counting  nitrogen  at 
15  cents  a  pound,  phosphorus  at  12  cents  in  acid  bone  black  and 
at  10  cents  in  ground  bone,  and  potassium  at  6  cents  a  pound), 
we  find  the  greatest  net  profit  from  commercial  plant  food  is  in 
the  use  of  phosphorus  alone. 

While  $5.04  worth  of  phosphorus  used  alone  produced  $12.17 
increase  (plot  3),  when  applied  in  addition  to  other  treatment,  the 
same  amount  of  phosphorus  produced  $14.28  over  nitrogen  (plot  5 
over  plot  2),  $17.64  over  potassium  (plot  7  over  plot  4),  and  $16.48 
over  nitrogen  and  potassium  (plot  9  over  plot  6).  Plots  12  and  35 
also  show  marked  increases  from  the  use  of  ground  bone.  Plot  17 
appears  to  give  too  low  results  compared  with  the  general  averages 
or  with  plot  15,  although  the  increase  from  plot  17  (NPK)  is  $8.48 
more  than  that  from  plot  6  (NK).  Thus,  under  every  condition 
phosphorus  has  much  more  than  paid  its  cost,  the  average  effect 
being  a  net  profit  of  about  200  per  cent  for  phosphorus  if  we  dis- 
regard the  cost  of  the  other  elements.  While  phosphorus  and  nitro- 
gen together  more  than  paid  the  combined  cost  and  produced  dis- 
tinctly better  crops,  this  system  yields  less  net  profit  than  the 
phosphorus  alone.  Similarly,  phosphorus  and  potassium  gave 
larger  increases,  but  less  profit  than  phosphorus  alone.  In  no  case 
has  either  nitrogen  or  potassium  paid  their  cost. 

It  is  noted  that  $9.96  worth  of  potassium  alone  produced  only 
$2.68  increase,  but  when  applied  with  phosphorus  the  average 
increase  ($16.83)  was  $4-66  more  than  that  from  phosphorus  alone 
($12.17).  Surely  we  should  try  to  secure  this  increase  by  some 
means.  If  kainit  at  one  third  the  cost  would  produce  the  same 
increase,  it  could  be  used  with  profit,  and  if  farm  manure  or  clover 
as  green  manure  would  produce  still  greater  increase  at  still  less 
cost,  we  should  plan  accordingly. 

Where  manure  was  applied  at  the  rate  of  12  tons  per  acre  in  four 
years  (6  tons  for  corn  and  6  for  wheat) ,  the  value  of  the  increase  is 


426     INVESTIGATION   BY   CULTURE   EXPERIMENTS 


).75,  as  an  average  of  the  24  years.  With  16  tons  the  increase 
was  $21.07,  and  with  20  tons  it  was  $22.73.  Thus,  the  12  tons  were 
worth  $1.65  a  ton,  16  tons  were  worth  $1.32  a  ton,  and  20  tons  were 
worth  $1.14  a  ton.  Thus,  we  may  say  that  the  first  12  tons  were 
worth  $1.65  a  ton,  the  next  4  tons  were  worth  33  cents  each,  and 
the  last  4  tons  were  worth  42  cents  each,  or,  as  an  average,  the  8 
tons  of  manure  applied  after  the  first  12  tons  were  worth  37  cents 
a  ton. 

The  "  cost  of  treatment  "  for  the  manure  applied  may  be  de- 
termined in  at  least  three  different  ways: 

First,  we  may  consider  the  manure  as  a  by-product  of  the  farm 
and  only  allow  for  the  cost  of  hauling  and  spreading,  for  which  30 
cents  a  ton  is  sufficient,  as  a  rule.  This  is  the  figure  used  in  the 
tables  under  discussion. 

Second,  we  may  estimate  the  cost  of  shipping  manure  from  some 
fairly  large  source  of  supply,  such  as  the  stock  yards  of  Chicago 
or  other  cities.  This  cost  would  probably  amount  to  $i  to  $2 
per  ton,  including  the  hauling  from  the  railway  station  and  spread- 
ing on  the  land. 

Third,  we  may  purchase  feed  and  thus  produce  manure  on  the 
farm  and  allow  for  the  manure  whatever  is  necessary! 

Table  78  shows  the  average  value  of  the  manure  applied  at  differ- 
ent rates,  and  also  the  profit  from  using  the  manure  that  is  regularly 
produced  on  the  farm. 

There  is  no  record  of  the  amounts  of  manure  applied  to  plot  8 
(on  the  four  series)  previous  to  the  beginning  of  these  experiments; 
but  its  residual  effect  is  very  apparent,  the  average  increase 
amounting  to  $3.23  per  acre  per  annum  for  the  24-year  period,  in 
comparison  with  the  unfertilized  plots. 

Caustic  lime  alone  decreased  the  crop  yields  as  an  average,  but 
when  used  with  manure  it  produced  an  average  increase  of  $2.49, 
or  about  25  per  cent  of  its  cost  at  $4.50  per  ton.  As  an  average 
of  the  two  tests,  the  light  application  of  land-plaster  produced 
practically  no  effect.  The  heavy  applications  of  ground  limestone 
produce  an  average  increase  of  $2.71,  or  not  quite  half  its  cost  at 
$1.50  per  ton.  In  the  last  four  or  five  years  the  effect  of  ground 
limestone  alone  is  apparently  decreasing,  —  a  result  to  be  expected 
sooner  or  later  where  no  manure  or  plant  food  is  returned  to  the 


PENNSYLVANIA   FIELD    EXPERIMENTS 


427 


land.  It  should  be  kept  in  mind,  too,  that  this  soil  is  not  very  acid, 
and,  consequently,  neither  burned  lime  nor  ground  limestone  would 
be  expected  to  produce  marked  effects. 

Since  phosphorus  and  manure  were  both  used  separately  with 
marked  effect  and  profit,  it  seems  probable  that  phosphorus  and 
manure  together  would  have  produced  still  more  satisfactory  re- 
sults; and,  if  the  action  of  the  ground  limestone  were  modified 
by  being  used  with  manure  as  much  as  was  that  of  caustic  lime, 
then  it,  too,  would  have  produced  increases  above  its  cost.  At  least, 
the  facts  suggest  that  manure,  phosphorus,  and  limestone  would 
make  a  very  profitable  combination;  and  green  manures  and  other 
crop  residues  could  of  course  be  used  in  place  of  animal  manures. 

In  Tables  79  and  80  are  recorded  the  24  years'  data  arranged  in 
two  periods  of  12  years  each.  While  24  years  is  too  short  a  period 
to  furnish  very  trustworthy  data  concerning  the  tendency  of  a  sys- 
tem of  farming  toward  increase  or  decrease  in  crop  yields  on  one 
piece  of  land  or  with  one  crop,  probably  the  average  results  from 
all  crops  on  the  four  series  of  plots  in  these  Pennsylvania  Experi- 
ments furnish  almost,  if  not  quite,  as  satisfactory  information 
along  this  line  as  any  of  the  Rothamsted  fields.  Such  results  are 
recorded  in  the  columns  headed  "  Value  of  the  four  crops."  It 
should  be  remembered  that  a  poor  year  for  oats  may  be  a  very  good 
year  for  winter  wheat,  corn,  or  hay,  and  that  four  crops  every  year 
for  27  years  furnish  almost  twice  as  much  data  as  the  single  system 
on  Agdell  field,  even  though  continued  for  60  years. 

As  an  average  of  the  20  plots  that  have  received  no  treatment 
since  1882  (including  the  No.  8  plots),  the  yields  have  decreased  as 
shown  below: 

AVERAGE  YIELDS  PER  ACRE  ON  20  UNFERTILIZED  PLOTS 


CROPS 

12-YEAR 

AVERAGE, 
1885  TO  1896 

1  2-  YEAR 

AVERAGE, 
1897  to  1908 

AVERAGE 
DECREASE 

Corn   bushels  

41.7 

27.7 

14.0 

Oats,  bushels  

76.7 

2^.O 

IT.y 

Wheat,  bushels    

13-3 

12.8 

.5 

Hay,  pounds    

3070 

2l8o 

800 

Average  value       

$11.05 

$8.18 

$2.87 

428    INVESTIGATION 'BY   CULTURE   EXPERIMENTS 


TABLE  79.   PENNSYLVANIA  EXPERIMENTS:  FOUR- YEAR  ROTATION 
Records  per  Acre  for  Three  Complete  Rotations,  1885  to  1896 


TREATMENT  FOR  EACH 
FOUR  YEARS 

AVERAGE  OF 
12  YEARS 

FROM  FOUR  ACRES 

6 
2 

0 

=- 

4 

Important 
Elements 
Applied 

Ni- 
tro- 
gen 
per 
Acre 
(Lb.) 

Form  of  Nitro- 
gen Applied 

TJorn 
Av. 
Bu. 
per 
Acre 

Oats 
Av. 
Bu. 
per 
Acre 

Wheat 
Av. 
Bu. 

per 
Acre 

Hay 
Av. 
Lb. 
per 
Acre 

Value 
of  the 
Four 
Crops 

Value 
f  Un- 
fertil- 
ized 

Value 
of  In- 
crease 

Cost 
of 
Treat- 
ment 

Profit 
or 
(-Loss) 

None  .    . 
N  (48  Ib.) 
P  (42  Ib.) 
K(i66lb.) 

34-7 
40-5 
45-o 

40.6 

34-7 
35-4 
39-1 
37-5 

ii.  i 

12.8 

14.6 

2480 
2640 
3400 
2900 

$37-77 
41.68 
47.90 
42.21 

$37-77 
38-15 
38.53 
38.91 

$  
7.20 
5-04 
9.96 

I 

48 

Dried  blood     . 

3-53 
9-37 

3-30 

(-3-67) 

4-33 
(-6.66) 

G 

7 
J 

g 
to 
ii 

12 

NP      .    . 
NK      .    . 
PK      .    . 

48 
48 

Dried  blood     . 
Dried  blood     . 

48.0 
40.6 
51-6 
5i-4 

42.4 
38-7 
44-6 
40.8 

18.2 
13-4 
15-7 
15-5 

3740 
3050 
4320 
4050 

53-48 
44-35 
55-39 
53-23 

39-29 
39-67 
40.05 

40.43 

14.19 
4.68 
15-34 
12.80 

12.24 
17.16 
15.00 

1-95 
(-12.48). 
•34 
12.80 

Manure  for  10  years  prior  to  1882 

NPK  .    . 
NPK  .    . 
NPK  .    . 
NPK  .    . 

48 
06 
144 

00 

Dried  blood     . 
Dried  blood     . 
Dried  blood     . 
Blood  and  bone 

5°-7 
50.0 
50.8 
Si-4 

46.1 
47-3 
45-4 
44-7 

19-3 

20.7 

22.1 

18.4 

4420 
423° 
4130 
4110 

58.35 
58.87 
59.26 
56.61 

40.81 
41.19 
41-57 
41-95 

17-54 
17.68 
17.69 
14.66 

22.20 
29.40 
36.60 
23.16 

(-4-66) 
(—11.72) 
(-18.91) 
(-8.50) 

I   < 

Land-plaster  (CaSO4),  640  Ib.    . 

42.8 

36.9 

13-9 

2810 

44.21 

42.33 

1.88 

I.OO 

.28 

M 

[S 

10 
'7 

None  .     . 
PK      .     . 

42-5 
Si-8 

51-9 
43-4 

35-3 
41.8 

42-5 
41.8 

I3-I 
16.4 

19-5 

1  8.0 

2690 
4140 
3910 
3920 

42.71 
54-57 
56-30 
52.09 

42.71 
42.64 

42-57 
42.50 

11.03 

13-73 
9-59 

15.00 

3.60 

22.20 

,            , 

10.13 

Yard  manure,  12  tons    .... 

NPK  .     .        48  (Dried  blood     . 

iS 

Yard  manure,  16  tons     .... 

47-8 
50.8 
49-9 
51-6 

44.1 
43-7 
43-2 

44-3 

20.4 
20.  6 
20.3 
21.9 

4140 
4210 
3890 
4030 

56.66 
57-94 
56.31 

58.77 

42-43 
42.36 
42.29 

42.22 

I4-23 
15.58 
14.02 
16.55 

4.80 

29.40 

6.00 
36.60 

9-43 
(-13-82) 

8.02 

(-20.05) 

10 
M 

NPK   .     .        96  (Dried  blood     . 

Yard  manure,  20  tons    .... 

11 

NPK  .     .      144  |Dried  blood    . 

M 

»3 

Lime  (CaO),  2  t 
nure,  12  tons 
Lime  (CaO),  2  toi 

ons;    yard  ma- 

50.2 
31-4 

44-o 
32-4 

19.7 
14.6 

4010 

2540 

56.59 
38.    5 

42-15 

42.08 

14.44 

(-3-53) 

12.60 
o.oo 

1.84 

(-12.53) 

is  

14 

27 

None  .    . 
PK      .    . 
NPKNa  . 
NPKNa  . 

NPKNa  . 

37-5 
50.8 
50.8 
50-7 
50-3 

36.6 
44-6 
43-7 
44-8 
44.4 

13-6 
16.4 
20.3 
21.4 

22.1 

2700 
4260 
4250 
4280 
4300 

42.00 
55-42 
57-85 
59-01 
50.30 

42.00 
42.26 
42-52 
42-78 
43-04 

13.16 
15-33 
16.23 
16.26 

15-00 

22.20 
29.40 

36.60 

48 
06 
144 

Sodium  nitrate 
Sodium  nitrate 
Sodium  nitrate 

(-6.87) 

(-13.17) 

(-20.34) 

II 

33 
34 

35 

PK      .    . 
NPK  .    . 
NPK  .    . 
NPK  .    . 

44.  S 
48.1 
51-3 
43-3 

43-o 
44-3 
46.2 
43-6 

15-9 
19.9 
22.7 
23-3 

4240 
4300 
4250 
3590 

52-43 
56-96 
60.46 
55-32 

43-30 
43-56 
43-82 
44.08 

9-13 
13.40 
16.64 
11.24 

15.00 
22.20 
29.40 
36.60 

48 
96 
144 

Amm.  sulfate  . 
Amm.  sulfate  . 
Amm.  sulfate  . 

(-8.80) 
(-12.76) 
(-25.36) 

Land-plaster  (CaSO4),  640  Ib.     . 
Ground  limestone  (CaC()s).4  tons 

38-4 
41.0 

46.8 
42.6 

36.3 
39-1 
43-6 
37-1 

13-3 

15-3 

1  8.8 
13-0 

30QO 
3280 
4690 
3330 

42.91 
46.63 

56.69 
45-13 

44-34 
44.60 

44.86 
45-13 

(-1.43) 
2.03 

11.83 

1.  00 

6.0 
23.16 

(-3-3) 
(-3-97) 
(-H-33) 

NPK  .    . 
None  .    . 

00 

Blood  and  tx>ne 

With  every  crop  there  has  been  a  decrease  in  yield,  varying  from 
£  bushel  of  wheat,  or  4  per  cent  of  the  crop,  to  14  bushels  of  corn, 
or  33  per  cent  of  that  crop.  The  average  yearly  value  of  produce 
from  one  acre  has  decreased  from  $11.05  to  $8.18;  and  this  $2.87 
represents  the  total  decrease,  not  for  a  24-year  period,  but  for  a 


PENNSYLVANIA   FIELD    EXPERIMENTS 


429 


TABLE  80.   PENNSYLVANIA  EXPERIMENTS  :  FOUR-YEAR  ROTATION 
Records  per  Acre  for  Three  Complete  Rotations,  1897  to  1908 


TREATMENT  FOR  EACH 
FOUR  YEARS 

AVERAGE  OF 
12  YEARS 

FROM  FOUR  ACRES 

Plot  No. 

Important 
Elements 
Applied 

Ni- 
tro- 
gen 
per 
Acre 
(Lb.) 

Form  of  Nitro- 
gen Applied 

"lorn 
Av. 
Bu. 
per 
Acre 

Oats 
Av. 
Bu. 
per 
Acre 

Wheat 
Av. 
Bu. 
per 
Acre 

Hay 
Av. 
Lb. 
per 
Acre 

Value 
of  the 
Four 
Crops 

Value 
if  Un- 
fertil- 
ized 

Value 
of  In- 
crease 

Cost 
of 
Treat- 
ment 

Profit 
or 
(-Loss) 

z 
• 
9 

4 

S'one  .     . 
N  (48  Ib.) 
P  (42  Ib.) 
K  (166  Ib.) 

23.6 
25.8 
35-8 
25-5 

2I.O 
23-5 
30.8 
24.9 

9.1 
10.7 
15-5 
10.4 

155° 
i6co 
2950 
1820 

825.58 
28.64 
41.47 
29.14 

$25-58 
26.06 
26.54 
27.03 

48 

Dried  blood     . 

2.58 
14-93 

2.  II 

$ 
7.20 
5-04 
0.96 

(-4.62) 
9.89 

6 

7 
8 

0 
IO 

II 

12 

NP      .     . 
NK     .    . 
PK      .    . 

48 
48 

Dried  blood     . 
Dried  blood     . 

37-6 
28.8 
45-i 
38.6 

35-5 
28.3 
37-2 
29.9 

19.6 
12.3 
19.7 

14-5 

3470 
2340 
4360 

3070 

47-94 
34-20 
53-82 
41.84 

27-51 
27.99 
28.48 
28.96 

20.43 
6.21 

25-34 

12.88 

12.24 
17.16 
15.00 

(?) 

8.19 
(-10.95) 
10.34 

12.88 

Manure  for  10  years  prior  to  1882 

NPK  .     . 
NPK  .     . 
NPK  .     . 
NPK  .     . 

48 
96 
144 
60 

Dried  blood     . 
Dried  blood     . 
Dried  blood     . 
Blood  and  bone 

44-5 
44-8 
46.5 
47-9 

37-7 
38.5 
38-7 
37-5 

22.6 

25-3 
27.2 

22-7 

4340 
4060 
4320 
4330 

55-73 
57-12 
59-89 
56.90 

29.44 
29-93 
30.41 
30.80 

26.29 
27.19 
29.48 
26.01 

22.20 
29.40 
36.60 
23.16 

4-09 
(-2.21) 
(-7.12) 

2.85 

y 

Land-plaster  (CaSO4),  640  Ib.     . 

29.6 

24.4 

I2.O 

2140 

32.50 

31-38 

1.  12 

1.  60 

(-.48) 

14 
IS 

None  .     . 
PK      .     . 



28.5 
43-9 
47.2 
38.7 

23.6 
33-9 
35-5 
33-8 

12.  1 
19-3 

25-4 

22.6 

2110 
4440 
4150 

3300 

31.86 
52.37 
57-40 
40.  6£ 

31-86 
31-77 
31.68 
31-50 

2O.OO 
25-72 
1  8.09 

15.00 

3.60 
22.2O 

5.60 

22.12 
(-4.H) 

16 

Yard  manure,  12  tons    .... 

17 

NPK  .     .        48  IDried  blood     . 

18 

10 

Yard  manure,  16  tons    .... 

45-i 
44-7 
50.2 
46.1 

37-9 
36.5 
38.5 
36.5 

27.O 

25-3 
27.9 

27.7 

4440 
4020 
4710 
3980 

59-38 
56.37 
62.78 
58.42 

31-50 
31-42 
31-33 
31-24 

27.88 
24-95 
31-45 
27.18 

4.80 
29.40 

6.00 
36.60 

23.08 

(-4-45) 
25-45 
(-9.42) 

NPK  .     ,       96  IDried  blood     . 

20 
21 

Yard  manure,  20  tons    .... 

NPK  .     .      144  IDried  blood     . 

22 
»3 

Lime  (CaO),  2  tons;    yard  ma- 
nure, 12  tons      
Lime  (CaO),  2  tons  

52.6 

23-3 

37-3 
21.9 

25-3 
I4.I 

4650 
2340 

61.26 
31.62 

3i-i5 

31.06 

30.11 

.56 

12.  6c 
9.00 

17-51 

(-8.44) 

24 

25 

26 

«7 

28 

None  .    . 
PK      .    . 
NPKNa  . 
NPKNa  . 
NPKNa  . 

23-3 
44.1 
47-7 
48.2 
49.0 

25.2 
35-7 
36.8 
37-4 
38.2 

I3-I 
20.5 
23-6 
26.2 

27-1 

2030 
4200 
4410 
4460 
4450 

1  30.98 
53-10 
57-49 
59.81 
60.93 

30.98 
3i-i7 
31-36 
31-55 
3i-74 

21.93 
26.13 
28.26 
29.19 

15.00 

22.20 
29.40 
36.60 

6-93 
3-93 
(-1.14) 

(-7-41) 

48 
96 
144 

Sodium  nitrate 
Sodium  nitrate 
Sodium  nitrate 

U  CM  U  10 
K)  M  O  O 

PK      .     . 
NPK  .    . 
NPK  .    . 
NPK  .    . 

40-5 
44.6 
42.6 
36.8 

34-2 
35-3 
36.0 
37-Q 
26.1 
25-7 

37-i 
25.2 

I8.7 
23-3 
24-3 
21.6 

3850 
3740 
3010 
2960 

49.08 
53-73 
51-75 
47.98 

3i-93 
32.12 
32.31 
32.50 

17-15 

21.  6l 

19.44 
15.48 

15.00 
22.2O 
29.40 
36.60 

2.15 
(-.59) 

(-9-96) 
(-21.12) 

48 
96 
144 

Amm.  sulfate 
Amm.  sulfate 
Amm.  sulfate 

33 

34 

35 
36 

Land-plaster  (CaSO4),  640  Ib.     . 
Ground  limestone  (CaCO3),  4  tons 

24.7 
28.8 
50.  1 
24.6 

12.9 

15.8 

24.6 
15-3 

20SO 
2470 
4690 
2130 

31-66 
36.26 
59.96 
33-27 

32.69 
32.88 

33-07 
33-27 

(-1.03) 

3.38 

26.89 

1.60 
6.00 
23.16 

(-2.63) 
(-2.62) 
3-73 

NPK  .    . 
None  .    . 

60 

Blood  and  bone 

12-year  period.  Of  course,  the  actual  decrease  will  grow  less  and 
less  as  soil  depletion  continues,  even  though  the  per  cent  of  decrease 
remain  constant,  for,  as  already  stated,  it  is  as  impossible  to  com- 
pletely exhaust  a  soil  as  it  would  be  to  exhaust  a  bank  account 
under  a  contract  that  only  2  per  cent  of  the  remaining  deposit 


430    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

could  be  withdrawn  at  any  one  time.  (Two  per  cent  per  annum  is 
approximately  the  rate  of  decrease  in  crop  values  from  the  20  un- 
fertilized plots  in  these  experiments.) 

There  are  only  four  combinations  of  commercial  plant  food  that 
have  maintained  the  productive  power  of  the  soil,  and  these  are  all 
combinations  of  the  three  elements;  plot  n  (with  dried  blood, 
144  Ib.  N),  plots  27  and  28  (with  sodium  nitrate,  96  and  144  Ib.  N), 
and  plots  12  and  35  (with  bone  and  blood,  60  Ib.  N).  However,  as 
an  average  of  the  24  years,  the  increase  was  not  sufficient  to  pay 
for  the  cost  of  treatment  on  any  of  these  plots.  It  appears,  however, 
that  during  the  second  1 2-year  period  plots  12  and  35  have,  as  an 
average,  paid  the  cost  of  the  plant  food  and  left  a  net  profit  of 
$3.29  from  the  four  acres.  Thus  it  will  be  noted  that  the  only 
plots  receiving  commercial  plant  food  that  has  paid  its  cost  even 
for  the  second  1 2-year  period  and  that  has  also  fully  maintained  the 
crop  yields  are  those  treated  with  ground  bone.  The  difference  in 
favor  of  ground  bone  is  not  sufficient  to  show  that  it  is  distinctly 
better  than  acid  phosphate,  but  we  may  surely  conclude  that  the  in- 
soluble bone  is  at  least  as  good  as  the  acidulated  form. 

During  the  first  1 2-year  period  the  net  profit  from  the  use  of 
manure  decreased  as  the  amount  of  manure  increased  above  12 
tons,  but  during  the  second  1 2-year  period  the  value  of  the  1 2-ton 
application  is  more  than  twice  as  much  as  during  the  previous  12 
years,  and  the  greatest  net  profit  per  acre  is  where  the  heaviest 
applications  are  made  (counting  30  cents  a  ton  for  manure),  but 
the  value  per  ton  is  still  greatly  in  favor  of  the  lighter  application, 
the  first  12  tons  being  worth  $2.14  a  ton  and  the  next  8  tons  only 
72  cents,  compared  with  $1.14  and  4  cents,  respectively,  for  the 
first  12  years.  While  the  larger  amounts  of  manure  show  a  distinct 
cumulative  effect  ($56.31  to  $62.78,  or  $6.47  a  year  from  the  four 
crops),  the  lightest  application  has  but  little  more  than  maintained 
the  earlier  crop  yields,  the  markedly  greater  apparent  profit  dur- 
ing the  second  12  years  being  due  to  the  decreased  yields  of  the 
unfertilized  land. 

In  Table  81  is  given  a  summary  of  the  effect  of  treatment  over 
the  24-year  period,  and  also  a  concise  statement  showing  the  actual 
or  absolute  profit  or  loss  from  every  system,  based  upon  the  aver- 
age yields  secured  during  the  second  1 2-year  period  in  comparison 


PENNSYLVANIA   FIELD    EXPERIMENTS 


431 


TABLE  81.   PENNSYLVANIA  EXPERIMENTS  :  FOUR-YEAR  ROTATION 
Summary  of  Financial  Results  from  Soil  Treatment  in  Four-year  Rotation 


TREATMENT  FOR  EACH  FOUR  YEARS 

FROM  FOUR  ACRES,  ONE  EACH  OF  CORN,  OATS,  WHEAT, 
AND  HAY 

I 

I; 

i 

a 
3 

4 

6 

7 

Important 
Elements 
Applied 

Ni- 
tro- 
gen 
per 
Acre 
(Lb.) 

Form  of  Nitrogen 
Applied 

Effect  of 
Treatment 
(Av.  of  24 
Years, 
1885  to  1908) 

Value 
of  the 
Four 
Crops 
Av.  of 

2d  12 

Yr. 

Value 
if  Un- 
fertil- 
ized 
Av.  of 

ISt   12 

Yr. 

Value  of 
Increase 
of  2d 
over  ist 
12  Yr. 

Cost 
of 

Treat 
ment 

For 
Permanent 
Systems 

Profit 

Loss 

Profit 

Loss 

None     . 
N  (48  Ib.) 
P  (42  Ib.) 
K(i661b.) 

825.58 
28.64 
41.47 
29.14 

$37-77 
38-15 
38.53 
38.91 

*=: 

$12.19 
16.71 

2.  10 

19.73 

48 

Dried  blood     .     . 

7-13 

4.18 

(-9-5I) 

(     o& 

7.20 
5-04 
9.96 

7.28 

NP  .     . 
NK  .    . 
PK  .    . 

48 
48 

Dried  blood     .     . 
Dried  blood     .     . 

5.06 

5-32 

12.02 

11.77 

47-94 
34-20 
53-82 
41.84 

39-29 
39-67 
40.05 

53-23 

8.65 
(-5.47) 

13.77 
(-11.30) 

12.24 
17.16 
15.00 

— 

3-59 
22.63 
1-23 
ii-39 



— 

8 
9 

10 

II 

ia 

y 

14 

y 

Manure  for  10  years  prior  to  1882    . 

NPK     . 
NPK     . 
NPK     . 
NPK     . 

48 
06 

144 
60 

Dried  blood     .     . 
Dried  blood    .     . 
Dried  blood     .     . 
Blood  and  bone   . 

— 

•33 
6.98 
13.10 

2.88 

55-73 
57-12 
59-89 
56.90 

40.81 
41.19 
41-57 
41-95 

14.92 
15.93 
18.32 

14.05 

22.20 
29.40 
36.60 
23.16 

— 

7.28 
13-47 
18.28 

8.21 

Land-plaster  (CaSO4),  640  Ib.     .     . 



.12 

32.50 

4a-33 

(-0.83) 

i.  60 

— 

"•43 

None     . 
PK   .     . 

.     .     . 

i.  20 
16.15 

31-86 
52.37 
57-40 
49.68 

42.71 
42.64 

42-57 
42.50 

(-10.85) 

9-73 
14.83 
7.18 

15.00 
3.60 
22.20 

10.85 
5-27 

15.02 

8.33 

11.23 

1  6 
17 

18 

Yard  manure,  12  tons    

NPK     .          48     Dried  blood     .     . 

Yard  manure,  16  tons  

16.27 
16.73 

9-15 
14.79 

59.38 
56.37 
62.78 

58.42 

42.43 
42.36 
42-29 
42.22 

16.95 
14.01 
20.49 
16.20 

4.80 
29.40 
6.00 
36.60 

12.15 
14.49 

15-39 
20.40 

iSL 

20 
21 
22 

33 

24 
2.S 
26 
27 

sL 
39 

30 
ji 

3_2_ 

33 

34 

NPK     .          96  |  Dried  blood     .     . 

Yard  manure.  20  tons   

NPK     .        144  |  Dried  blood     .     . 

Lime  (CaC 
12  tons 
Lime  (CaC 

)),  2  tons;    yard  manure, 

9.64 

10.45 

61.26 
31.62 

42-15 

42.08 

19.11 

(-10.46) 

12.60 
9.00 

6.5i 

19-46 

None     . 
PK  .    . 

NPKNa 
NPKNa 
NPKNa 

2-59 

30.98 
53-10 
57-49 
59.81 
60.93 

42.00 
42.26 
42.52 
42.78 
43-04 

(-11.02) 
10.84 
14.97 
17.03 
17.89 

15.00 
22.20 
29.40 
36.60 

1  1.  02 
4.16 
7-23 
12.37 
18.71 

48 
96 

144 

Sodium  nitrate     . 
Sodium  nitrate     . 
Sodium  nitrate     . 

1.49 
7.22 
13-99 

— 

PK  .    . 
NPK     . 
NPK     . 
NPK     . 

48 
96 

144 

Ammonium  sulfate 
Ammonium  sulfate 
Ammonium  sulfate 



1.70 
4.68 
"•37 
23.16 

49.08 
53-73 
51-75 
47-98 

43-30 
43-56 
43-82 
44.08 

5.78 

10.17 
7-93 

3.00 

15.00 
22.20 
29.40 
36.60 

— 

9.22 
12.03 
21.47 
32.70 

Land-plaster  (CaSO4),  640  Ib.     .     . 
Ground  limestone  (CaCO3),  4  tons 

E 

2.83 
3-29 
3-74 

31-66 
36.26 

59.96 
33-27 

44-34 
44.60 

44.86 
45-13 

(-12.68) 
(-8.34) 
15.10 
(-11.86) 

i.  60 
6.00 
23.16 

E 

14.28 
14-34 
8.06 
11.86 

35 
3f> 

NPK     . 
None    . 

60 

Blood  and  bone   . 

with  yields  of  the  unfertilized  land  during  the  previous  12  years. 
By  this  means  only  are  we  able  to  avoid  the  exaggerated  influ- 
ence which  is  always  credited  to  the  soil  treatment  when  com- 
parison is  made  with  the  decreasing  productiveness  of  unfertilized 
check  plots. 


432 


INVESTIGATION    BY   CULTURE   EXPERIMENTS 


For  this  purpose  these  Pennsylvania  data  are  probably  the  most 
valuable  the  world  affords;  and,  in  the  author's  opinion,  this 
volume  presents  no  more  significant  facts  than  are  contained  in 
Table  81. 

The  decrease  in  productive  value  of  the  unfertilized  plot  is 
markedly  uniform,  notwithstanding  the  variation  among  those 
plots,  the  average  decrease  in  value  per  acre  per  annum  being  $2.87 
and  the  widest  variation  from  that  average  being  18  cents.  Plot  8, 
which  had  received  manure  during  the  10  years  previous  to  1882, 
shows  the  same  decrease  as  the  other  four  unfertilized  plots,  the 
average  for  the  four  others  being  $11.46,  while  plot  8  shows  $11.39. 
The  average  yield  of  the  No.  8  plots  during  the  second  1 2-year 
period  is  slightly  less  than  the  average  yield  of  the  four  other 
unfertilized  plots  during  the  first  period. 

From  Table  81,  it  will  be  seen  that,  for  permanent  systems  of 
farming,  no  form  or  combination  of  commercial  plant  food  has  been 
used  with  profit,  the  annual  loss  from  four  acres  varying  from 
$2. 46  with  phosphorus  alone,  $3.59  with  phosphorus  and  nitrogen, 
and  $5  (as  an  average)  with  phosphorus  and  potassium,  to  $20.40 
and  $32.70  with  the  complete  fertilizer  carrying  the  largest  amounts 
of  dried  blood  and  ammonium  sulfate,  respectively. 

Manure  costing  30  cents  a  ton  shows  net  profit  in  all  cases,  but 
the  profit  is  greatly  reduced  by  the  addition  of  caustic  lime  at 
$4.50  a  ton;  although  the  lime  produced  sufficient  increase  to  pay 
$2.14  a  ton  for  it  for  use  with  manure,  and  the  effect  of  the  lime- 
manure  treatment  is  distinctly  cumulative,  especially  upon  the 
clover  and  timothy,  the  yield  of  hay  from  the  lime-manure  plots 
being  640  pounds  higher  during  the  second  12  years  than  during 
the  earlier  period,  and  500  pounds  more  than  from  the  manure 
alone  during  the  second  period. 

Would  ground  limestone  at  less  cost  produce  a  greater  benefit, 
and  would  the  use'  of  phosphorus  also  with  farm  manure  or  green 
manure  produce  still  greater  net  profit?  The  Ohio  investigations 
answer  the  latter  question  with  a  most  emphatic  affirmative. 
(See  Tables  37,  38,  39,  and  396.) 

Thus  it  will  be  noted  that,  as  an  average  of  the  same  12  years 
(1897  to  1908),  the  value  of  the  produce  per  acre  per  annum  is 
$14.35  where  12  tons  of  manure  are  used  in  the  Pennsylvania 


PENNSYLVANIA   FIELD   EXPERIMENTS  433 

four-year  rotation,  $13.76  where  8  tons  of  manure  are  used  in  the 
Ohio  three-year  rotation  (corn,  wheat,  and  clover,  —  see  Table 
396),  and  17.29  where  40  cents  worth  of  raw  phosphate,  or  80 
cents'  worth  of  acid  phosphate,  was  used  in  connection  with  8  tons 
of  manure  in  the  Ohio  rotation. 

From  Table  81  it  can  easily  be  determined  that  the  absolute 
value  per  ton  of  manure  for  permanent  systems  is  $1.24  for  the 
smallest  amount  used,  $1.06  for  the  medium  amount,  and  $1.02 
for  the  heaviest  application.  For  the  additional  8  tons  (12  to  20) 
the  manure  was  worth  71  cents  a  ton. 

Based  upon  comparison  with  the  yields  from  the  untreated  land 
during  the  last  12  years,  the  12  tons  of  manure  for  the  Pennsyl- 
vania four-year  rotation  were  worth $2. 14  a  ton;  while,  for  the  same 
12  years,  the  8  tons  of  manure,  in  the  Ohio  three-year  rotation, 
were  worth  $1.82  a  ton  for  the  yard  manure  and  $2.41  a  ton  for 
the  stall  manure.  (See  Tables  37,  38,  and  39.) 

Director  Thorne  has  emphasized  the  fact  that  the  Ohio  experi- 
ments at  Wooster  were  started  on  fields  that  had  for  many  years 
been  under  exhaustive  tenant  husbandry,  and  the  unfertilized 
plots  at  Wooster  during  the  last  12  years  are  more  nearly  compar- 
able with  those  at  State  College  during  the  same  12  years  than  dur- 
ing the  first  12  years.  Thus  the  average  annual  produce  per  acre 
for  the  same  three  crops,  corn,  wheat,  and  clover,  was  $10.35  f°r 
the  first  12-year  period  and  $7.77  for  the  second  12-year  period, 
in  Pennsylvania;  while  for  the  last  12  years  the  average  value 
in  Ohio  has  been  $8.06,  these  values  being  based  upon  the  normal 
unfertilized  plots,  the  No.  8  plots  at  State  College,  and  the  No.  i 
and  No.  n  plots  at  Wooster  (see  Table  40)  not  being  included. 
If  the  oats  are  included,  the  Pennsylvania  figures  would  be  $10.47 
for  the  first  12  years  and  $7.61  for  the  second  period. 

In  Pennsylvania  Bulletin  90  (1909),  Director  Hunt  summa- 
rizes the  results  of  the  first  25  years  covered  by  these  experiments. 
The  following  tabular  statement,  containing  figures  based  upon 
Pennsylvania  values,  may  be  of  special  interest  to  the  student  of 
Eastern  conditions. 

The  upper  part  of  this  table  shows  the  total  weights  of  the  seven 
products  harvested,  including  ear  corn,  corn  stover,  oats,  oat  straw, 
wheat,  wheat  straw,  and  hay;  and  the  lower  part  shows  the  total 


434    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

values  at  75  cents  per  100  pounds  of  ear  corn,  32  cents  a  bushel 
for  oats,  $1.33  per  100  pounds  of  wheat,  $2.50  a  ton  for  corn  stover 
and  straw,  and  $10  a  ton  for  hay. 

TABLE  SIP.   PENNSYLVANIA  FIELD  EXPERIMENTS 


PLANT 
FOOD 
APPLIED 

UN- 
FERTIL- 
IZED 

NITRO- 
GEN 
(48  Lb.) 

PHOS- 
PHORUS 
(42  Lb.) 

POTAS- 
SIUM 
(166 
Lb.) 

NITRO- 
GEN 

AND 

PHOS- 
PHORUS 

NITRO- 
GEN 

AND 

POTAS- 
SIUM 

PHOS- 
PHORUS 

AND 

POTAS- 
SIUM 

BLOOD 
(48  Lb. 
N), 
PHOS- 
PHORUS, 
POTAS- 
SIUM 

BLOOD 
(96  Lb. 
N), 
PHOS- 
PHORUS, 
POTAS- 
SIUM 

BLOOD 

d44 
Lb.  N), 
PHOS- 
PHORUS, 
POTAS- 
SIUM 

YEARS 

POUNDS  OF  TOTAL  PRODUCTS  FROM  FOUR  ACRES.    (Averages) 

1882-86 
1887-91 
1891-96 
1897-01 
1902-06 

14679 

T4339 
12611 
9562 
9848 

14479 
14060 
11461 
8326 

8955 

14628 
15204 
14647 
12229 
12907 

14598 
14476 
12404 
8780 
958l 

16176 
16469 
16622 

14038 
14358 

I5031 
15959 
12840 
10450 
11778 

16577 

17090 
17764 
15440 
16368 

16889 
17492 
18352 
15867 

T6335 

17994 
18706 

I94I5 
16981 
17780 

17933 
19210 
19786 
17221 
18008 

1882-06 

I22IO 

"457 

13922 

11967 

15534 

12814 

16647 

16986 

I8I37 

18653 

YEARS 

VALUES  OF  TOTAL  PRODUCTS  FROM  FOUR  ACRES.    (Averages) 

1882-86 
1887-91 
1892-96 
1897-01 
1902-06 

$75-35 
75-46 
64.29 
49.16 
50.88 

$73.61 
74-13 
58-57 
42.36 

45-5° 

$74-76 
79.66 
75-58 

61.80 
67.28 

$73.90 
74.61 
61.34 
43-63 
47-3° 

$83-35 
86.15 

85-75 
71.91 

74.83 

$74.82 

77-85 
62.88 

5I-85 
54-13 

$85.34 
87.56 
89.08 
76.81 
83.73 

$85.20 
87.81 

90-75 
77.92 
83.87 

$89.21 
93-49 
95-59 
83.07 
90.92 

191-53 
94-70 
96-56 
85.25 
95.87 

1882-06 

$63.03 

$58.84 

$71-79 

$60.16 

880.40 

$64.31 

$84.51 

$85.10 

$90.47 

$02.79 

1887-96 
1897-06 

$69.88 
50.02 

$66.35 
43-93 

$77-62 

65-54 

$67.98 

45-47 

$85.95 

73-37 

$70.37 
52.99 

$88.32 
80.27 

$89.28 
80.90 

$94-54 
87.00 

$95.63 
90.56 

The  last  two  lines  in  the  table  are  ic-year  averages  computed 
by  the  author,  all  other  figures  being  copied  from  Pennsylvania 
Bulletin  90. 

In  his  discussion  of  these  experiments,  Doctor  Hunt  makes  the 
following  comments  (Bulletin  90,  page  14) : 

"The  most  striking  fact  brought  out  by  this  table  is  that  the  application  of  48 
pounds  of  phosphoric  acid  and  100  pounds  of  potash  in  alternate  years  to  a 
rotation  consisting  of  corn,  oats,  wheat,  and  mixed  hay  (timothy  and  clover), 
namely,  to  the  corn  and  wheat,  has,  during  twenty-five  years,  maintained  the 
crop-producing  power  of  the  soil.  There  is  no  evidence  thus  far  to  show  but 
what  the  supply  of  nitrogen  can  be  indefinitely  maintained  on  this  limestone 
soil  by  means  of  a  rotation  containing  clover,  provided  the  mineral  fertilizers  are 
abundantly  supplied." 


PENNSYLVANIA   FIELD    EXPERIMENTS  435 

These  statements,  if  true,  are  of  tremendous  significance  to 
American  agriculture,  for  they  refer  to  the  oldest  experiments  of 
the  kind  in  the  United  States;  furthermore,  the  phosphorus- 
potassium  plot  is  repeated  four  times  in  every  series,  so  that  the 
average  results  are  from  16  different  plots  of  normal  soil  every  year 
for  twenty-five  years,  and  they  must  be  considered  highly  trust- 
worthy. The  small  amount  of  limestone  contained  in  this  Penn- 
sylvania soil  can  very  easily  be  supplied  to  any  other  soil  by  the 
direct  application  of  ground  limestone. 

It  will  doubtless  be  agreed  by  all  that  the  results  of  the  first  few 
years  at  the  beginning  of  a  rotation  and  fertilizer  experiment  are 
not  to  be  considered  as  comparable  with  the  subsequent  results. 
There  are  several  reasons  for  this;  but,  for  the  present  purpose, 
it  is  sufficient  to  consider  that  nitrogen  may  not  have  been  a  limit- 
ing element  for  all  crops  at  the  beginning.  The  data  given  in 
Table  8iP  are  not  satisfactory  for  making  any  study  of  this  special 
point,  because  the  averages  for  the  unfertilized  land  include  the 
results  from  plot  8  which  is  represented  to  have  received  annual 
applications  of  manure  during  the  ten  years  previous  to  1882, 
because  of  which  the  addition  of  nitrogen  alone  appears  (from 
Table  8iP)  to  have  actually  decreased  the  crop  yields,  which  is 
not  the  case  if  we  accept  the  system  of  comparison  adopted  for 
Tables  78  to  81. 

It  must  be  evident  from  every  point  of  view  that  nitrogen  was 
not  the  limiting  element  for  all  crops  at  the  beginning  of  these 
experiments.  It  is  evident,  however,  that  phosphorus  was  the 
principal  limiting  element  at  the  beginning. 

Now,  for  the  sake  of  simplicity,  let  us  assume  that  from  a  given 
type  of  very  uniform  soil  (see  Table  87)  sufficient  phosphorus  will 
become  available  during  the  season  (1903)  to  meet  the  needs  of  a 
54-bushel  crop  of  corn  (plot  102),  while  sufficient  nitrogen  will  be 
liberated  for  a  62-bushel  crop.  The  application  of  nitrogen  with- 
out phosphorus  could  not  be  expected  to  appreciably  increase  the 
yield  (plot  103),  while  the  addition  of  sufficient  phosphorus  with- 
out nitrogen  should  increase  the  yield  from  54  to  62  bushels,  but 
unless  nitrogen  was  also  supplied,  the  yield  could  not  be  expected 
to  go  above  62  bushels.  However,  by  applying  nitrogen  in  addition 
to  phosphorus,  the  yield  might  be  still  further  increased  (as  to  69 


436     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

bushels  on  plot  106)  to  a  point  where  perhaps  the  supply  of  avail- 
able phosphorus  again  becomes  the  limiting  factor.  In  other 
seasons  or  in  later  years,  these  conditions  may  become  reversed, 
with  nitrogen  as  the  most  limiting  element,  and  phosphorus  with 
little  or  no  effect  except  in  addition  to  nitrogen.  (Note  the  results 
for  1907  and  1908,  in  Table  87.) 

We  can  conceive  of  conditions  under  which  the  supply  of  nitro- 
gen naturally  liberated  from  the  soil,  when  supplemented  by  that 
secured  from  the  air  by  clover  grown  in  the  rotation,  will  meet  the 
needs  of  the  crops  grown  for  several  years,  during  which  the  nitro- 
gen does  not  become  the  limiting  element  to  any  marked  degree, 
and  it  must  be  plain  that  in  such  case  the  crop  yields  give  little  or 
no  information  concerning  the  maintenance  of  nitrogen  in  the  soil. 
Thus,  it  is  only  after  nitrogen  becomes  the  limiting  element,  in 
any  given  system,  that  the  crop  yields  become  an  index  as  to  the 
possible  permanency  of  the  nitrogen  supply. 

In  soils  that  are  markedly  deficient  in  phosphorus,  that  element 
may  still  remain  the  limiting  element  after  the  first  small  appli- 
cation has  been  made,  provided  the  increased  supply  of  available 
phosphorus  is  not  sufficient  to  raise  the  crop  yields  to  the  point 
where  nitrogen,  for  example,  becomes  the  limiting  factor;  and  it  is 
easily  conceivable  that  the  increase  produced  by  supplying  po- 
tassium in  addition  to  phosphorus,  in  the  Pennsylvania  experi-  ' 
ments,  was  due,  in  part  at  least,  to  the  power  of  potassium  salts 
to  hold  the  phosphorus  in  available  form.  Even  where  heavy 
applications  of  potassium  were  made,  the  sodium  nitrate  was  more 
effective  than  dried  blood,  and,  if  only  sodium  nitrate  had  been 
added  with  phosphorus,  the  sodium  would  very  probably  have 
produced  nearly  as  marked  results  as  were  produced  by  potassium. 

There  are  too  marked  variations  among  duplicate  plots  on  the 
Pennsylvania  field  to  justify  fine  distinctions,  and  even  on  more 
uniform  land  there  are  many  factors  involved  with  different  crops 
and  different  seasons;  but  we  dare  not  ignore  the  fact  (Table  8iP) 
that  the  average  value  of  the  crops  from  four  acres  receiving  phos- 
phorus-potassium treatment  decreased  from  $88.32  to  $80.27 
during  ten  years,  from  1891-1892  to  1901-1902,  which  are  the 
middle  points  of  the  two  lo-year  periods.  Whether  we  consider 
the  values  or  the  pounds  of  products,  the  apparent  decrease  is 


PENNSYLVANIA   FIELD   EXPERIMENTS 


437 


approximately  10  per  cent  in  10  years,  and  if  this  rate  of  decrease 
continues,  we  may  expect  the  average  values  to  drop  during  suc- 
cessive lo-year  periods  from  $80  to  $72,  to  $65,  to  $59,  to  $53,  and 
to  $48,  in  the  next  70  years. 

It  will  be  noted  that  the  dividing  point  between  the  two  lo-year 
periods  in  Table  8iP  is  exactly  the  same  as  between  the  two  12- 
year  periods  referred  to  in  Tables  79  and  80;  and  it  may  also  be 
noted  that,  as  an  average  of  the  four  phosphorus-potassium  plots, 
the  average  yields  during  the  second  1 2-year  period  show  6.4 
bushels  less  corn,  8.3  bushels  less  oats,  and  25  pounds  less  hay,  but 
with  3.5  bushels  more  wheat,  than  during  the  first  12  years.  These 
figures  mean  that  for  each  rotation  (four  years)  the  yields  have 
decreased  by  2.1  bushels  of  corn,  2.8  bushels  of  oats,  and  8  pounds 
of  hay,  while  the  yield  of  wheat  shows  an  increase  of  1.2 
bushels.  The  algebraic  sum  shows,  as  an  average,  that  each  re- 
curring rotation  produces  $2.36  lower  crop  values  from  an  acre  of 
land  than  during  the  preceding  four  years. 

All  this  must  remind  us  of  the  mineral  plot  on  Agdell  field,  where 
the  yields  of  turnips  and  legumes  are  still  well  maintained,  and  the 
wheat  yield  has  appreciably  increased,  while  only  the  barley  has 
very  markedly  decreased. 

Mathematically,  it  is  not  possible  for  the  roots  and  stubble  of 
the  clover  crop  to  furnish  sufficient  nitrogen  for  the  other  four 
crops,  —  timothy  (associated  with  the  clover),  corn,  oats,  and 
wheat;  but  the  question  again  arises,  whether  important  amounts 
of  atmospheric  nitrogen  may  not  be  fixed  that  are  not  thus  ac- 
counted for.  It  is  fully  established  that  the  azotobacter  (and 
possibly  other  similar  bacteria)  fixes  measurable  quantities  of 
free  nitrogen  under  favorable  conditions;  and  it  is  also  fully  es- 
tablished that  the  bacteria  which  commonly  live  in  symbiotic 
relationship  with  legume  plants  can  fix  appreciable  amounts  of 
free  nitrogen,  under  suitable  artificial  conditions,  and  entirely 
independent  of  legume  plants.  It  is  thus  conceivable  that  these 
may  fix  nitrogen  to  a  greater  or  less  extent  while  they  continue  to 
live,  not  in  the  tubercles  of  growing  clover,  but  upon  the  dead  and 
decaying  residues;  and,  if  such  is  the  case,  it  is  exceedingly 
probable  that  the  presence  of  carbohydrate  matter  (as  in  plant 
residues)  and  a  liberal  supply  of  available  mineral  plant  food  in  a 


438    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

limestone  soil,  will  furnish  the  very  favorable  conditions,  although 
the  data  thus  far  reported  from  Agdell  field  (Table  75)  show  a 
greater  average  loss  of  nitrogen  (245  pounds  from  the  surface  9 
inches  only)  from  the  phosphorus  plots  than  from  the  untreated 
plots  (105  pounds)  in  the  legume  rotation;  while,  as  an  average  of 
the  four  plots,  the  fallow  rotation  lost  less  nitrogen  than  the  legume 
system. 

It  should  be  kept  in  mind,  also,  that  the  organic  matter  of  the 
soil  contains  nitrogen  as  well  as  carbon,  and  that  the  amount  of 
combined  nitrogen  liberated  from  this  organic  matter  may  be 
nearly  or  quite  sufficient  to  meet  the  needs  of  the  bacteria  that  can 
be  supported  by  the  carbonaceous  food.  In  laboratory  cultures 
the  fixation  of  nitrogen  amounts  to  about  10  milligrams  for  each 
gram  of  sugar  (mannite)  consumed  by  the  "free-living"  bacteria.1 
Thus  the  amount  of  nitrogen  fixed  is  equal  to  about  i  per  cent  of 
the  carbonaceous  food  consumed;  whereas  the  organic  matter  of 
the  soil  contains,  as  a  rule,  more  than  2  per  cent  of  nitrogen. 

On  Broadbalk  field  the  nitrogen  2  content  of  the  surface  9  inches 
decreased  during  28  years  (1865  to  1893)  by  285  pounds  (from  2722 
to  2437)  on  plot  3  (unfertilized),  by  265  pounds  (from  2782  to  2517) 
on  plot  5  (minerals),  and  by  63  pounds  (from  3034  to  2971)  on 
plot  7  (minerals  and  86  pounds  of  nitrogen) ;  while  the  only  in- 
creases shown  are  633  pounds  (from  4343  to  4976)  on  plot  2  (farm 
manure),  and  131  pounds  (from  2991  in  1865  to  3015  in  1881  and 
to  3122  in  1893)  on  plot  14,  which  receives  ammonium  salts  (86 
Ib.  N),  acid  phosphate,  and  magnesium  sulfate.  (The  possibility 
of  erosion  or  deposit  from  surface  washing  should  not  be  over- 
looked. Compare  the  nitrogen  content  of  plots  u,  12,  13,  and  14 
with  respect  to  each  stratum,  as  shown  in  Table  73.) 

1  In  this  connection  attention  is  called  to  the  point  that  if  increased  growth  of 
plants  is  caused  by  the  use  of  pyrogallol,  as  reported  from  the  unverified  experi- 
ments of  Whitney  and  Cameron,  it  may  be  due  to  the  fixation  of  free  nitrogen  by 
the  nonsymbiotic  bacteriv  that  find  in  pyrogallol  a  suitable  carbonaceous  food 
supply.  It  is  known  that  the  addition  of  sugar  to  ordinary  soil  deficient  in  nitrogen 
will  increase  the  growth  of  nonleguminous  plants  because  of  the  increased  nitrogen 
fixation  by  the  "free-living"  bacterh. 

J  All  of  these  determinations  were  made  by  the  older  soda-lime  method  and 
are  considered  trustworthy  for  comparison,  but  the  1893  analyses  reported  in  Table 
73  were  made  by  the  newer  Kjeldahl  method,  which  gives  somewhat  higher  and 
more  nearly  correct  results. 


PENNSYLVANIA   FIELD   EXPERIMENTS  439 

As  already  stated,  a  study  of  the  present  nitrogen  content  of  the 
soil  of  Agdell  field  will  probably  furnish  more  satisfactory  informa- 
tion than  can  be  secured  from  any  other  source  at  this  time. 

It  is  very  evident  that  the  loss  of  nitrogen  in  drainage  water 
usually  exceeds  the  addition  in  rainfall;  and,  unless  there  are 
sources  of  nitrogen  other  than  can  be  found  by  the  analysis  of  the 
legume  plants  (tops,  roots,  and  tubercles),  we  must  make  provision 
to  supply  a  sufficient  excess  of  nitrogen  in  farm  manure,  crop  resi- 
dues, or  otherwise,  to  meet  the  needs  of  large  crops  and  to  overcome 
the  loss  in  drainage  from  rich  land. 

In  Bulletin  221  of  the  New  Jersey  Agricultural  Experiment 
Station,  issued  July,  1909,  Voorhees  and  Lipman  report  in  detail 
the  results  of  ten  years'  investigations  with  twenty  culture  experi- 
ments (in  triplicate)  in  which  corn,  oats,  wheat,  and  timothy  were 
grown  in  rotations  in  60  cylinders,  each  4  feet  long  and  23^  inches 
in  diameter,  set  in  the  earth  and  open  at  both  ends,  so  as  to  approach 
natural  conditions  for  drainage.  Cow  manure,  fresh  and  leached, 
and  cow  dung  (solid  excrement),  fresh  and  leached,  were  used  with 
and  without  sodium  nitrate,  ammonium  sulfate,  and  dried  blood, 
in  various  combinations. 

At  the  beginning  of  the  experiment,  in  1898,  the  surface  soil 
(8  inches  deep)  contained  155.47  grams  of  nitrogen  in  each  cylinder. 
The  amounts  of  nitrogen  applied  during  the  ten  years  varied  from 
38.25  grams  in  the  leached  dung  to  58.31  grams  in  the  fresh  manure 
and  sodium  nitrate  combined.  The  total  amounts  of  nitrogen 
removed  in  the  sixteen  crops  harvested  during  the  ten  years  varied 
from  21.88  to  36.70  grams;  and  the  total  loss  of  nitrogen,  other 
than  that  contained  in  the  crops  removed,  varied  from  25.12  to 
39.38  grams.  Thus,  in  these  long-continued  and  very  carefully 
conducted  experiments  the  absolute  chemical  control  shows  loss 
of  nitrogen  by  leaching  far  in  excess  of  possible  additions  by  rain- 
fall, azotobacter,  etc. 

After  a  full  consideration  of  the  data  accumulated  in  these 
experiments  with  respect  to  their  bearing  upon  the  question  of 
denitrification,  the  authors  make  the  following  statements: 

"We  must  conclude,  therefore,  that  at  least  with  cow  manure,  used  at  the 
rate  of  sixteen  tons  per  annum  for  a  period  of  ten  years,  no  destruction  of  ni- 
trates takes  place.  In  view  of  the  long  duration  of  the  experiment,  and  of  the 


440    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

comparatively  large  amounts  of  manure  used  in  the  course  of  the  ten  seasons,  we 
must  assume  that  denitrification  is  not  a  phenomenon  of  economic  importance,  in 
general  farming  and  under  average  field  conditions.  ...  We  have  no  hesita- 
tion in  emphasizing  again  the  view  expressed  above  that  under  the  wide  range 
of  field  conditions,  denitrification  is  not  a  phenomenon  of  economic  significance 
to  the  general  farmer." 

With  our  present  knowledge  we  should  not  do  less  than  to  base 
our  practice  upon  the  known  mathematical  and  chemical  facts 
concerning  the  nitrogen  requirements  of  crops  and  the  nitrogen 
content  of  manures,  legume  crops,  and  crop  residues,  keeping  in 
mind,  of  course,  that  there  are  some  soils,  such  as  peaty  lands  and 
others  excessively  rich  in  organic  matter,  which  should  be  cropped 
for  years  with  little  or  no  return  of  nitrogen. 


CHAPTER  XXI 

OHIO    FIELD    EXPERIMENTS 

ASIDE  from  the  experiments  outlined  in  Table  40,  which  deal 
especially  with  manure,  alone  and  reenforced  with  different  mate- 
rials, the  Ohio  Experiment  Station  has  conducted,  for  15  years, 
two  very  extensive  and  valuable  investigations  by  means  of  plot 
experiments,  relating  to  the  maintenance  of  soil  fertility.  In 
one  of  these  a  five-year  rotation  is  practiced  on  five  separate 
fields  or  series,  each  of  which  contains  30  tenth-acre  plots  about  i 
by  16  rods,  each  of  the  five  crops,  corn,  oats,  wheat,  clover,  and 
timothy,  being  represented  every  year  (excepting  the  clover  and 
timothy  for  the  first  two  years).  In  the  other  investigation, 
potatoes,  wheat,  and  clover  are  grown  in  a  three-year  rotation  on 
three  separate  series,  each  of  which  contains  34  tenth-acre  plots  of 
the  same  shape.  Each  of  the  crops  is  represented  every  year  (ex- 
cept wheat  the  first  year  and  clover  the  first  two  years) .  The  detail 
plan  of  these  experiments  and  the  average  results  secured  for  the 
15  years  (1894  to  1908)  are  shown  in  Tables  82  and  83. 

Seasonal  variations  are  too  great  to  justify  an  attempt  to  de- 
termine from  the  data  secured  in  fifteen  years  (only  13  years  with 
clover  and  timothy)  whether  the  productive  power  of  the  soil  is 
increasing  or  decreasing.  It  will  be  recalled  that  Jethro  Tull  grew 
13  crops  of  wheat  in  succession  on  the  same  land  without  the  use 
of  manure  or  fertilizers,  and  from  the  data  secured  the  conclusion 
was  drawn,  "  that  a  good  crop  of  wheat,  for  any  number  of  years, 
may  be  grown  every  year  upon  the  same  land  without  any  manure 
from  first  to  last."  A  more  recent  similar  illustration  is  furnished 
by  the  Minnesota  Experiment  Station,  showing  average  yields  of 
14.7  bushels  of  wheat  from  1893  to  1898,  and  17.2  bushels  from 
1899  to  1904,  where  wheat  was  grown  every  year  without  manure 
or  fertilizer. 

441 


442 


TABLE  82.     OHIO  EXPERIMENTS:   FIVE-YEAR  ROTATION 
Average  Records  per  Acre  for  Three  Rotations,  1894  to  1908 


TREATMENT  FOR  EACH  FIVE 
YEARS 

AVERAGE  YIELDS  PER 
ACRE 

FROM  FIVE  ACRES 

C 

y. 

~z 

G* 

i 

a 
_J_ 
4 
S 
6 

Elements 
Applied 
(Lb.) 

Forms  of    Plant 
Food,  if  not  Stand- 
ard1 

a 

a 
<u 
!* 

1 
U 

Oats,  15  Years  (Bu.) 

Wheat,  15  Years  (Bu.) 

Clover,  13  Years  (Lb.) 

£~  J3  Timothy,  13  Years  (Lb.) 
5  o  o 

Value  of  the  Five  Crops 

Value  if  Unfertilized 

Value  of  Increase 

Cost  of  Treatment 

Profit  from  Five  Acres 

i  1  Net  Profit  (Per  Cent) 

Nitrogen 

Phosphorus 

Potassium 

10.6 
18.4 

I2.O 

820 
2410 
2170 

842.43 
55-32 
47.14 

^42.43 
42-34 
42-25 

$ 

•j 

$ 

- 

JO 

icS 

(P)    
(K)  

39-4 
tf.2 

40.2 
35-6 

12.98 
4.89 

2.40 
6.48 

10.58 

(—   1.59) 

441 
loss 

16 
76 

20 

r: 

(N)        .... 

31-3 
36.3 

[6.0 

32.2 

31-6 
35-7 
46.5 

10.8 

12.8 

24.1 

1940 
2250 
3000 

2780 
3180 
3480 

42.15 
48.67 
66.36 

42.15 
41.94 
41-73 

6-73 
24.63 

11.40 
13-80 

(-  4-67) 
10.83 

loss 
78 

(NP)     .... 

8 

Q 

7" 

20 

ioS 
1  08 

(PK)     .         .    . 

31-3 

10.8 

1820 
2740 
2190 

2610 
3080 
2970 

41-51 
59-85 
48.64 

41-51 
41.21 
40.91 

18.64 
7-73 

8.88 
17.88 

9.76 
(  —  10.15) 

no 
loss 

(NK)    .... 

36.7 

S6.2 

13-5 

10 

1  1 

12 

76 

114 

20 
JO 

1  08 
108 

(NPK)       .    .    . 

30.0 
48.4 
48.7 

31-6 
49-9 
48.9 

10.7 
27.0 
28.0 

1830 
3120 
3230 

2SSO 
3620 
351° 

40.61 
71-03 

7i-54 

40.61 
40.70 
40.79 

30-33 
30-75 

2O.2? 
25.98 

10.05 

4-77 

50 

18 

13 

M 

15 

Si 

25 

IS 

10 

3° 

75 
41 

31-0 
45-9 
35-9 

31-4 
38.9 
32.3 
29-5 
47-4 
38.9 

10.8 
25.2 
24-0 
9-5 

22.1 
2O.S 

1760 
2760 
235° 

2500 
3250 
2950 

40.88 
63.41 
54-96 

40.88 
39-89 
38.90 

23-52 
1  6.06 

13-95 

7-41 

9-57 
8.6  <; 

69 

J^7_ 

16 

17 
i8_ 

38 

1  08 

.    .    . 

28.7 
47.2 

5°-7 

1640 
2910 
3660 

2480 
3220 
4060 
2610 
349° 
3090 

37-91 
64.60 

66.03 

37-91 
38.91 
30.91 

25.69 
27.02 

15.78 
4.80 

9.91 

22.22 

63 

463 

Yard  manure,  16  tons     .     . 

10 

20 

Yai 

(1 

nun 

ure,  8  tons  .     .     . 

32-3 
44-1 
46.8 

3<J-7 
37-o 
46.7 

16.9 
23-4 

2810 
2640 

40.90 
57-27 
63-96 

40.90 
39.82 
38.74 

17-45 
25-22 

2.40 
15.78 

15-05 
0.44 

627 
60 

21 
22 
23 
24 

38 

30 

108 

Oil  meal,  690  Ib. 

38 
38 

30 
30 

ioS 
1  08 

Blood,  300  Ib.     . 
Amm.  sul.,  165  Ib. 

29.0 
46.9 

47-7 

29.9 
46.9 
48.3 

9.9 
22.2 
22.8 

1530 
2600 
2720 

2340 
3060 
2980 

37-66 
63.01 
64.25 

37-66 
38.83 
40.00 

24.18 
24-25 

15.78 
15.78 

8-40 
8.47 

54 
54 

as 

20 

VJ 

7" 
7" 

20 
20 

108 
108 

Raw  bone,  220  Ib. 
Acid    bone    black 
280  Ib.  .     .     . 

32.0 
46-9 

48.2 

3i-3 
46.7 

49-3 

IO.^ 
23-5 

26.4 

1780 
3290 

2890 

2650 
3680 

3490 

41.16 
67.79 

69.28 

41.16 
41-95 

42.74 

25-84 
26.54 

19-88 
2O.28 

5-96 
6.26 

30 
31 

a8 

20 

30 

76 
38 

JO 

30 

1  08 
108 

Basic  slag,  260  Ib. 
Tankage,  675  Ib. 

34-2 
49-3 
47-7 

32.5 
47-4 
43-7 

10.6 

24.6 

21.8 

1920 
3060 
3050 

2880 
3830 
379° 

43-54 
69.37 
65-59 

43-54 
43-54 
43-54 

25.83 
22.05 

19.88 
I5-I8 

S-95 
6.87 

30 

45 

1  The  standard  forms  of  plant  food  are  50  Ib.  of  dried  blood  (25  Ib.  on 
plots  17  and  24,  and  20  Ib.  on  plot  26)  and  the  balance  of  the  nitrogen  in  sodium 
nitrate  (70  Ib.  N  in  440  Ib.  of  nitrate),  acid  phosphate  (20  Ib.  P  in  320  Ib.  of 
phosphate),  and  potassium  chlorid  (108  Ib.  K  in  260  Ib.  of  potassium  chlorid, 
"muriate"  of  potash).  Where  some  other  material  is  used  for  any  element,  as 
linseed-oil  meal  for  nitrogen,  less  acid  phosphate  and  potassium  chlorid  are  applied, 
so  as  to  correct  for  the  phosphorus  and  potassium  carried  in  the  oil  meal. 

The  possible  influence  of  abnormal  years  upon  the  average  of  a 
few  years  is  well  illustrated  in  the  wheat  yields  of  these  experi- 


OHIO   FIELD    EXPERIMENTS  443 

ments  at  Wooster,  Ohio,  which  are  summarized  in  Table  82. 
The  average  yield  of  wheat  on  the  ten  unfertilized  plots  was  19.3 
bushels  per  acre  in  1894  and  19.5  bushels  in  1908,  while  i.i  bushels 
was  the  average  yield  for  1896,  and  i.i  bushels  was  also  the  average 
yield  for  1900.  The  average  was  3.0  bushels  in  1895  and  13.9 
bushels  in  1907. 

As  a  rule,  land  that  has  been  heavily  cropped  with  almost  con- 
tinuous grain-growing,  and  with  little  or  no  manure,  will  produce 
markedly  better  crops  for  several  years  after  a  good  rotation  sys- 
tem is  well  established,  and  this  fact  often  leads  to  a  most  serious 
error  on  the  part  of  the  farmer;  namely,  to  the  conclusion  that 
crop  rotation  will  maintain  the  productive  power  of  the  land. 
The  rotation  helps  to  avoid  the  breeding  of  insects  that  would 
prey  upon  a  single  crop,  and  it  is  beneficial  in  various  other  ways, 
especially  when  clover  or  other  biennial  or  perennial  crops  are 
introduced  which  increase  somewhat  the  amount  of  active  organic 
matter  in  the  soil,  the  decomposition  of  which  will  furnish  succeed- 
ing grain  crops  with  some  plant  food  contained  in  such  crop  resi- 
dues and  with  additional  and  often  more  important  amounts  liber- 
ated from  the  soil  by  the  decaying  organic  matter. 

Of  course  this  benefit  upon  the  grain  crops  cannot  be  secured 
until  after  the  clover  or  grass  crops  have  been  seeded  and  grown, 
and  the  land  again  plowed  up  and  used  for  the  grain  crops;  and, 
furthermore,  on  land  which  has  not  grown  clover  for  many  years, 
the  infection  with  the  clover  bacteria  is  sometimes  so  imperfect 
that  the  first  clover  crop  serves  chiefly  to  increase  the  bacteria, 
and  thus  furnish  a  perfect  infection  for  the  second  seeding,  which 
very  commonly  produces  a  larger  yield  than  the  first  seeding; 
and,  if  so,  it  may  be  followed  by  correspondingly  larger  yields  of 
corn  or  other  grains. 

In  consequence  of  these  different  influences  the  crop  yields  may 
be  better  the  second  or  third  rotation  than  during  the  first.  With 
the  Pennsylvania  experiments  we  can  pass  over  a  preliminary 
period  of  three  years,  and  then  consider  the  results  of  three  com- 
plete rotations  followed  by  three  other  complete  rotations;  and, 
by  including  in  our  comparison  the  four  crops  grown  every  year, 
the  results  are  significant;  but  as  yet  no  such  comparisons  are 
possible  with  the  Ohio  investigations.  We  can,  however,  note  the 


444    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

effect  of  the  plant  food  applied  by  comparing  the  yields  of  the 
treated  and  the  untreated  plots,  but  we  must  not  assume  that  all 
systems  of  treatment  that  appear  profitable  from  this  comparison 
will  prove  to  be  absolutely  profitable  in  continued  practice. 

The  common  soil  at  Wooster  contains  about  1880  pounds  of 
total  nitrogen,  960  pounds  of  acid-soluble  phosphorus  (perhaps 
uoo  pounds  of  total),  and  31,000  pounds  of  total  potassium,  in  2 
million  pounds  of  the  surface  soil.  Thus  it  is  markedly  deficient 
in  both  nitrogen  and  phosphorus,  and  it  may  also  be  stated  that 
this  soil  is  distinctly  acid.  During  the  last  six  or  eight  years  liberal 
applications  of  lime  have  been  made  to  half  or  all  of  each  of  the 
five  series,  the  unfertilized  plots  having  been  limed  the  same  as  the 
others;  and  in  practically  all  cases  distinct  benefit  has  resulted 
for  all  crops,  the  most  marked  effect  being  upon  clover,  and  then 
naturally  upon  the  crops  following  clover. 

Table  82  illustrates  very  well  the  fact  that  the  farmer  cannot 
always  afford  to  raise  the  largest  possible  crops  that  can  be  pro- 
duced by  applications  of  commercial  plant  food.  The  largest 
gross  return  from  the  five  acres  is  from  the  No.  12  plots  ($71.54), 
but  the  amount  of  net  profit  and  the  per  cent  of  net  profit  from  that 
plot  are  less  than  from  any  other  profitable  treatment. 

It  is  plain  that,  as  an  average,  for  this  rotation,  phosphorus  is 
the  most  limiting  element,  but,  after  phosphorus,  the  nitrogen  limit 
is  also  very  distinct.  Thus  phosphorus  alone  increases  the  returns 
from  five  acres  from  $42.34  to  $55.32,  with  a  net  profit  of  $10.58, 
or  441  per  cent  on  the  money  invested  in  the  20  pounds  of  the 
phosphorus  applied.  The  addition  of  $11.40  worth  of  nitrogen 
(with  sodium)  with  phosphorus  produces  an  increase  of  $11.65 
more  than  with  phosphorus  alone,  thus  showing  a  net  profit  for 
nitrogen  of  25  cents,  or  5  cents  an  acre,  or  2  per  cent  on  the  money 
invested.  In  all  other  cases  nitrogen,  as  well  as  potassium,  has 
been  applied  at  a  loss,  and  in  every  other  case  wherever  the  use  of 
commercial  plant  food  has  been  profitable  the  entire  profit  has  been 
made  by  the  phosphorus,  and  after  the  phosphorus  had  paid  for 
some  net  loss  caused  by  the  other  elements. 

Both  the  invoice  (soil  analysis)  and  the  crop  yields  agree  in  the 
deficiency  of  nitrogen  and  phosphorus;  but  these  two  sources  of 
information  appear  to  disagree  as  to  the  need  of  potassium.  There 


OHIO   FIELD   EXPERIMENTS  445 

is  some  evidence  which  indicates  that  more  or  less  of  the  effect  of 
the  potassium  salt  is  due  to  indirect  action  rather  than  as  plant 
food.  Thus  the  sodium  nitrate  on  plot  17  produces  distinctly 
better  results  than  the  oil  meal  or  dried  blood  on  plots  21  and  23. 
(About  twice  as  much  potassium  was  applied  in  the  Pennsylvania 
Experiments,  but  the  sodium  nitrate  shows  superiority  over  dried 
blood  during  the  second  1 2-year  period,  after  the  supply  of  humus 
has  probably  become  somewhat  depleted.  If  the  blood  nitrogen 
failed  to  become  available  with  sufficient  rapidity,  one  would 
expect  it  to  produce  cumulative  benefits  like  the  manure,  to  some 
extent,  but  such  is  not  the  case.) 

In  the  Ohio  experiments  the  average  effect  of  potassium  has  been 
nearly  the  same,  whether  applied  alone  ($4.89  on  plot  3),  in  addi- 
tion to  phosphorus  ($5.66  on  plot  8),  or  in  addition  to  both  nitrogen 
and  phosphorus  ($5.70  on  plot  u),  although  nitrogen  and  phos- 
phorus without  potassium  (plot  6)  produced  an  increase  of  $24.63, 
or  59  per  cent  above  the  unfertilized  land  ($41.73).  More  than  half 
of  this  increase  must  be  credited  to  phosphorus  alone,  and  less  than 
half  to  nitrogen  after  phosphorus;  while,  in  reverse  order,  nitro- 
gen gets  one  fourth  and  phosphorus  three  fourths  of  the  credit. 
Nitrogen  alone  produced  an  increase  of  only  $6.73  (plot  5),  and  it 
is  questionable  if  this  increase  is  not  in  part  due  to  indirect  action, 
such  as  increasing  the  availability  of  the  soil  phosphorus,  the  effect 
on  the  clover  crop  being  as  marked  as  on  the  other  crops.  As  an 
average  the  effect  of  nitrogen  and  potassium  together  is  only 
$7.73,  leaving  a  net  loss  of  $10.15;  but  the  addition  of  20  pounds 
of  phosphorus,  under  this  most  favorable  condition,  pays  back  this 
loss  and  adds  a  net  profit  of  $10.05,  making  a  gross  increase  of 
$22.60,  or  almost  ten  times  the  cost  of  the  phosphorus,  which 
certainly  establishes  well  the  fact  that,  if  the  farmer  can  supply 
the  nitrogen  in  clover  or  in  manure,  and  liberate  the  potassium 
etc.  by  means  of  the  decaying  organic  matter,  there  must  be  large 
profit  from  the  use  of  purchased  phosphorus.  (In  fine-ground  rock 
phosphate  the  20  pounds  of  phosphorus  will  cost  about  60  cents, 
at  present  prices.) 

Phosphorus  is  evidently  the  limiting  element  on  all  plots  where 
76  pounds  of  nitrogen  have  been  supplied,  practically  no  increase 
being  produced  by  the  extra  nitrogen  on  plot  12,  and  twice  as  much 


446     INVESTIGATION   BY   CULTURE    EXPERIMENTS 

phosphorus  being  removed  from  plot  1 1  in  the  crops  produced  as  is 
applied  during  the  five  years,  as  is  easily  determined  by  computa- 
tion. It  is  impossible  that  the  crop  yields  will  be  permanently 
maintained  under  this  system,  unless  the  partially  depleted  sur- 
face soil  is  removed  by  erosion  at  least  in  corresponding  rapidity  as 
the  phosphorus  is  removed  in  crops. 

On  the  other  hand,  nitrogen  must  be  the  limiting  element  where 
30  pounds  of  phosphorus  were  used;  but,  wherever  the  amount  of 
phosphorus  was  increased,  the  nitrogen  was  also  reduced,  so  that 
it  is  impossible  to  determine  what  effect  is  produced  either  by  in- 
creasing the  phosphorus  or  by  reducing  the  nitrogen. 

The  experiments  on  plots  14  and  15  are  essentially  variations  in 
amount  used  of  a  complete  fertilizer;  but  on  15  the  fertilizer  is 
applied  for  wheat,  and  on  14  for  corn  and  wheat,  while  on  all  other 
plots  the  fertilizers  are  applied  in  three  portions,  for  corn,  oats,  and 
wheat.  (The  manure  is  applied  in  two  equal  portions,  for  corn 
and  wheat.) 

The  comparison  of  the  different  forms  of  nitrogen  is  valuable, 
because  nitrogen  is  the  limiting  element  on  those  plots;  while  the 
comparison  of  different  phosphates  is  likewise  so  planned  that 
phosphorus  is  the  limiting  element. 

The  insoluble  phosphorus  in  raw  bone,  basic  slag,  and  tankage 
is  reckoned  at  10  cents  a  pound. 

In  the  main  the  Ohio  experiments  reported  in  Table  82  were 
designed  to  supply  about  the  same  quantities  of  nitrogen,  phos- 
phorus, and  potassium,  as  were  removed  in  the  average  crops  pro- 
duced by  farmers  on  the  ordinary  land  in  that  section  of  the  state. 

Where  complete  fertilizers  are  used  by  farmers  in  a  rotation  of 
this  kind,  about  200  pounds  per  acre  may  be  applied  for  corn  and 
again  for  wheat,  making  400  pounds  for  the  rotation.  The  most 
common  composition  is  the  2-8-2  goods,  containing  2  per  cent 
of  ammonia  (NH3),  8  per  cent  of  "  available  phosphoric  acid" 
(P2O6),  and  2  per  cent  of  potash  (K2O);  or,  in  the  400  pounds, 
about  7  pounds  of  nitrogen,  14  pounds  of  soluble  (and  3  pounds 
of  insoluble)  phosphorus,  and  7  pounds  of  potassium.  In  other 
words,  the  total  amounts  applied  in  four  or  five  years  would  furnish 
enough  nitrogen  for  one  5-bushel  crop  of  corn,  enough  phosphorus 
for  one  7o-bushel  crop,  and  enough  potassium  for  one  ic-bushel 


Plot 

2 

5 
8 

12 

IS 

16 

Fertilizer 
Factory  brand  "  A  "      

.  In 
Corn 
Bus. 
7.62 

crease  per  a< 
Wheat 
Bus. 
10.62 

"•39 
.       8.13 
8.50 
13.22 

14.24 

Factory  brand  "  B  "      

4.88 

Factory  brand  "  C  "     

•2.70 

Factory  brand  "  D  "     

Raw  bone  meal      

6.40 

11.02 

OHIO   FIELD    EXPERIMENTS  447 

crop;  and  yet  such  use  of  plant  food  is  the  most  common  practice 
in  the  Eastern  and  Southern  states. 

In  this  connection  the  following  quotation  from  Director  Thorne 
of  the  Ohio  Station  is  of  interest  (Ohio  Farmer,  January  2,  1904) : 

"For  seven  years  raw  bone  meal  and  steamed  bone  meal  have  been  used  in 
comparison  on  the  Strongsville  test  farm,  side  by  side  with  four  brands  of 
factory-mixedj  acidulated,  complete  fertilizers,  these  brands  representing  some 
of  the  most  reputable  manufacturers  in  the  state,  and  ranging  from  4  per  cent 
of  ammonia,  10  per  cent  phosphoric  acid  and  4  per  cent  potash,  to  i  per  cent 
ammonia,  6  per  cent  phosphoric  acid,  and  i  per  cent  potash.  The  fertilizers  are 
all  applied  at  the  rate  of  200  pounds  per  acre  to  corn  and  wheat,  grown  in  ro- 
tation and  followed  by  one  year  in  clover.  Following  is  the  average  increase  ob- 
tained from  each  crop: 

• Increase  per  acre — 

Hay 
Lbs. 

675 

658 

458 
350 

1300 

"  At  present,  steamed  bone  meal  furnishes  available  phosphorus  in  prob- 
ably the  cheapest  and  most  effective  form  in  which  it  can  be  bought." 

In  Table  83  are  recorded  the  average  results  secured  from  the 
potatoes-wheat-clover  rotation  during  the  fifteen  years,  1894  to 
1908. 

It  should  be  stated  that  plots  32,  33,  and  34  were  started  one 
year  later  for  the  potatoes  and  clover,  and  two  years  lat,er  for  the 
wheat,  than  the  other  plots,  and  that  assumed  yields  for  those  plots 
for  the  one  or  two  years  are  introduced  (based  upon  the  yields  of 
other  plots  subsequently  producing  about  the  same  as  these  three), 
in  order  that  the  comparison  of  the  averages  may  be  fair.  This  is 
essential,  because  the  yield  of  potatoes  the  first  year  and  the  yields 
of  wheat  the  first  two  years  were  markedly  smaller  than  the  average 
of  all  subsequent  years. 

The  yield  of  wheat  straw  is  shown  because  the  data  are  available, 
and  they  complete  the  record  for  all  crops,  and  especially  because 
comparison  is  thus  afforded  of  the  yields  of  grain  and  straw. 
As  an  average  for  good  yields  for  each  bushel  of  wheat  there  are 
about  100  pounds  of  straw. 

The  financial  statement  is  based  upon  the  following  prices, 
potatoes,  30  cents  (and  50  cents)  a  bushel ;  wheat,  70  cents ;  clover 


448     INVESTIGATION   BY   CULTURE   EXPERIMENTS 


TABLE  83.    OHIO  EXPERIMENTS:  THREE-YEAR  ROTATION 
Average  Records  per  Acre  for  Five  Rotations,  1894  to  1908 


TREATMENT  FOR  EACH  THREE 
YEARS 

AVERAGE  YIELDS 
PER  ACRE 

RESULTS  FROM  THREE  ACRES 

Plot  No. 

Ele- 
ments 
Applied 
(Lb.) 

Forms  of  Plant  Food, 
if  not  Standard  ' 

3 

s 

2 
• 

£ 
v> 

1 
« 

(2 

Wheat  Grain,  14  Years 
(Bu.) 

o  i!  «  1  Wheat  Straw,  14  Years 
8ot  1  (Bu.) 

Clover  Hav,  13  Years 
(Lb.) 

Value  of  the  Three  Crops 

Value  if  Unfertilized 

Value  of  Increase 

Cost  of  Treatment 

Profit  from 
Treatment 

Price  of 
Potatoes 

Nitrogen 

Phosphorus 

Potassium 

3°^ 

S°? 

I 

9 
Ji_ 
4 

6 

83 

170.8 
185.5 
184.8 

3°-9 
36-4 
32.7 
3°-5 
3°-7 
36.4 

3610 
3840 
345° 

$83.70 
92.65 
88.68 

$83.70 
83.29 
82.88 

*B 
9-36 
5-80 

• 

• 

— 

20 

(P)    

2.40 
4-98 

6.96 
.82 

9.87 
3-56 

(K)    

.is 

38 

20 
20 

— 

(X)         

'?i-3 
178.3 
1  86.  i 

2970 
3200 
3810 

3240 
3500 
3670 

82.46 
85.48 
92.32 

82.46 
80.65 
78.84 

4.83 
13.48 

5-70 
8.10 

(-.87) 
5-38 

1-47 

IO.22 

(NP)       

8 

g 

58 

83 
83 

" 

157-2 
192.8 
174-8 

28.4 
36.1 
34-4 

2760 
3350 
3220 

3330 

3540 
3610 

77-03 
93-73 
87-35 

77-03 
77-39 

77-75 

16.34 
9.60 

7-38 
10.68 

8.96 
(-1.08) 

15.85 
1.98 

(PK) 

(NK)     

10 

II 

12 

38 

02 

20 
20 

83 
83 

(NPK)                .    . 

160.6 
184.3 
100.8 

29.6 
38.6 
38-4 

2740 
3720 
3850 

3070 
3490 
3660 

78.11 
92.78 
95.10 

78.11 
77-75 
77-39 

I5-03 

17.71 

13.08 
16.68 

1-95 
1.03 

6.91 

7-51 

13 

14 

IS 

5» 

Si 

3° 

.50 

125 

i  »S 

(Extra  on  potatoes)  . 
(All  on  potatoes) 

157-3 
196.2 
194.9 

28.8 
38.3 
36.8 

2670 
3800 
3520 

3230 
3700 
3700 

77.04 
96.77 
95-33 

77.04 

75-54 
74.04 

21.23 
21.29 

i8.75 
18.75 

2.48 

2-54 

10.85 
11.24 

If) 
17 

IS 

148.5 
157-8 
162.2 

27.2 
31-3 
32.5 

2450 
3050 
3130 

2980 
3480 
3860 

72.53 
79-69 
82.00 

72.53 
71-03 
69-53 

Yard  manure,  4  tons  on  wheat 
Yard  manure,  8  tons  on  wheat 

8.66 
13.46 

i.  20 
2.40 

7.46 
11.06 

9.69 
14-54 

II) 

20 
.'I 

25 
as 

2O 
20 

83 
83 

143.0 
189.2 
181.7 

24-5 
34-0 
34-i 
24.1 
34-9 
34-8 

2380 
330° 

.1200 

2180 
3220 
310° 

2660 
3430 

3120 

2790 
3140 
3130 

68.03 
90-85 
87-74 

68.03 
68.64 
69.25 

22.21 
18.40 

11-13 
11-13 

11.08 
7-36 

19.94 
14-34 

Oil  meal,  460  Ib. 

22 
33 

->4 

148.7 
181.9 
181.6 

60.85 
88.42 
88.23 

69-85 
69.65 
69-45 

7.64 
7-65 

»s 

»5 

2O 
20 

83 
83 

Dried  blood    .     . 
Amm.  sulfate  .     . 

18.77 
18.78 

11.13 
11.13 

14-45 
14-57 

»5 
a6 

27 

146.2 
176.0 
185.8 

24-7 
35-6 
37-o 

2270 
3350 
3630 

243° 
3740 

2700 
3420 
3250 
2900 
37io 

69.25 
87.98 
91.29 

69-25 
70.00 
70-75 

38 
38 

2O 
20 

83 
83 

Raw  bone  meal    . 
Acid  bone  black  . 

17.98 
20.54 

12.68 
13.08 

5-30 
7.46 

10.03 
14.82 

28 

20 

3» 

2O 

».? 

Basic  slag   .     .     . 

151.2 
184.8 

24.9 
37-6 

71.49 
92.80 

71.49 
72.24 

20.65 

12.68 

7-07 

14.09 

30 

Yard  manure,  8  tons  on  potatoes 

2OO.O 

3i-9 

3090 

3700 

93-43 

72.99 

20.44 

2.40 

18.04 

26.60 

31 

ja 

Yard  manure,  16  tons  on  wheat 

160.3 

1  88.0 

24.8 
33-4 

2410 
33io 

2760 
3450 

73-73 
90.13 

73-73 
70.29 

19.84 

4.80 

15.04 

22.27 

.1.1 

vl 

25 

20 

83 

Tankage     .... 

179.0 
'35-o 

33-4 
23-2 

3080 
1990 

2650 
222O 

85-03 
63.40 

66.85 
63-40 

18.18 

10.73 

7-45 

M-57 

1  The  standard  forms  include  both  dried  blood  (usually  50  Ib.)  and  sodium 
nitrate  (usually  200  Ib.),  acid  phosphate,  and  potassium  chlorid,  the  applications 
being  divided,  in  most  cases,  between  the  potatoes  and  wheat. 

hay,  $6.00  a  ton ;  nitrogen,  15  cents  a  pound ;  phosphorus,  12  cents 
(10  cents  in  raw  bone,  slag,  and  tankage)  ;  and  potassium,  6  cents. 
The  price  of  potatoes  varies  greatly,  and  for  that  reason  the  figures 


OHIO   FIELD    EXPERIMENTS  449 

given  in  the  last  column  of  Table  83  are  based  upon  the  price  of 
50  cents  a  bushel  for  potatoes,  while  30  cents  a  bushel  is  the  price 
used  in  the  other  computations.  Of  course  the  increase  in  crop 
values  resulting  from  treatment  is  not  computed  at  the  delivered 
price  for  marketable  potatoes,  but  sometimes  this  would  be  justi- 
fied, because  the  treatment  may  largely  increase  the  percentage  of 
marketable  potatoes,  and  even  with  other  crops  the  improvement 
in  quality,  as  well  as  in  quantity,  may  be  a  factor  of  some  impor- 
tance. In  any  case,  potatoes  belong  to  the  crops  of  intensive  agri- 
culture, the  largest  average  yield  (200  bushels)  amounting  to  $60 
an  acre  at  30  cents,  and  to  $100  an  acre  at  50  cents  a  bushel.. 

Part  of  the  field  upon  which  these  experiments  have  been  con- 
ducted was  virgin  soil,  cleared  from  forest  for  the  purpose,  and  all 
of  the  land  was  fairly  rich  at  the  beginning. 

The  average  of  16  analyses  of  soil  from  the  "  East  Farm,"  where 
the  five-year  rotation  (Table  82)  and  reenforced  manure  experi- 
ments (Table  40)  are  conducted,  and  5  analyses  of  soil  from  the 
"  South  Farm,"  where  the  potato-wheat-clover  rotation  experi- 
ments are  under  way,  show  that  the  South  Farm  soil  contains  about 
one  half  more  acid-soluble  phosphorus  than  the  East  Farm  soil. 
It  is  also  somewhat  richer  in  acid-soluble  potassium,  while  in 
total  nitrogen  the  East  Farm  soil  is  slightly  richer.  By  referring 
to  the  column  headed  "  Value  if  unfertilized  "  (Table  83),  it  will 
be  seen  that  the  natural  productiveness  of  the  land  varies  markedly 
from  plot  i  ($83.70)  to  plot  19  ($68.03)  an^  plot  34  ($63.40); 
but  the  oft-repeated  check  plot  (unfertilized)  makes  possible  a 
comparison  that  could  not  be  made  without  it.  On  the  other  hand, 
we  can  never  be  sure  that  the  treatment  applied  to  one  plot  (as 
phosphorus  to  plot  2,  for  example)  has  produced  the  same  total 
increase  as  it  would  have  produced  if  applied  to  some  other  plot 
(as  to  plot  20,  for  example) .  Thus  the  actual  total  yield  from  plot  2 
($92.65)  is  greater  than  that  from  plot  20  ($90.85) ,  but  the  computed 
increase  from  plot  20  is  more  than  twice  as  great  ($22.21)  as  that 
from  plot  2  ($9.36).  The  fact  is  that  more  plant  food  is  removed 
from  plot  2  than  from  plot  20,  but  this  is  also  true,  of  course,  with 
respect  to  the  adjoining  unfertilized  control  plots.  These  difficul- 
ties are  emphasized,  however,  by  comparing  plots  u  and  20,  both 
of  which  receive  the  three  elements,  nitrogen,  phosphorus,  and  po- 


450    INVESTIGATION   BY   CULTURE    EXPERIMENTS 

tassium,  in  the  standard  forms  (the  nitrogen  chiefly  in  sodium 
nitrate). 

The  treatment  for  these  two  plots  differs  only  by  the  addition 
of  13  pounds  more  nitrogen  to  plot  n  (plot  u  receives  50  pounds 
of  dried  blood  for  wheat,  and  plot  20  only  25  pounds).  The  total 
yields  (except  potatoes)  are  greater  from  plot  n,  and  the  total 
value  of  the  three  crops  is  greater  from  plot  n  ($92.78)  than 
from  plot  20  ($90.85);  but  the  increase  from  plot  20  ($22.21)  is 
much  greater  than  from  plot  n  ($15.03),  and  the  net  profit  from 
20  ($11. 08  or  $19.94)  is  several  times  as  great  as  from  n  ($1.95 
or  $6.91).  In  comparison  with  such  plots  as  14  and  27,  it  seems 
evident  that  plot  20  gives  results  above  normal;  while  it  is  like- 
wise evident  that  plot  n  shows  increases  below  normal,  in  com- 
parison with  such  plots  as  8  and  24.  These  opposite  abnormalities 
develop  the  striking  discrepancy  between  n  and  20.  A  study 
of  the  yearly  details  shows  that  for  the  first  five  years  (1895 
to  1899)  the  increase  from  treatment  was  greater  every  year  in 
the  wheat  crops  from  plot  n,  the  average  difference  being  3.6 
bushels,  whereas  during  the  next  five  years  (1900  to  1904)  the  in- 
crease in  wheat  was  greater  every  year  on  plot  20,  the  average 
difference  being  2.6  bushels.  As  an  average  of  the  four  years, 
1905  to  1908,  the  increase  from  plot  20  averaged  2.5  bushels  more 
wheat  than  from  n,  although  in  two  of  these  years  the  treatment 
gave  about  equal  results  on  those  plots.  As  an  average  of  the  first 
six  years  (1896  to  1901)  plot  n  produced  79  pounds  less  clover 
than  the  unfertilized  control  plots,  while  on  plot  20  the  treatment 
produced  an  average  increase  of  630  pounds. 

These  results  and  discrepancies  serve  to  emphasize  the  uncer- 
tainty of  drawing  correct  conclusions  from  a  single  field  experiment, 
even  when  continued  for  several  years.  On  the  other  hand,  most 
of  the  results  from  this  potato- wheat-clover  rotation  are  concord- 
ant, and  justify  confidence.  Indeed,  there  is  marked  agreement  in 
most  cases  where  direct  comparison  is  possible.  Thus  the  increases 
from  like  amounts  of  plant-food  elements  on  plots  21,  23,  24,  and 
33  vary  only  from  $18.18  to  $18.78. 

In  harmony  with  the  results  from  all  other  sources,  the  use  of 
phosphorus  on  normal  soils  proves  highly  profitable,  the  increase 
produced  by  phosphorus,  both  alone  and  in  addition  to  other 


OHIO   FIELD   EXPERIMENTS  451 

elements,  being  sufficient  to  pay  for  the  phosphorus  (even  in  acid- 
phosphate)  and  leave  a  net  profit  of  200  to  300  per  cent.  The  use 
of  commercial  nitrogen  or  potassium,  alone  or  in  combination,  is 
of  doubtful  advantage  with  potatoes  at  30  cents,  but  at  50  cents 
for  potatoes  the  potassium  has  been  a  good  investment,  although, 
with  sufficient  manure  or  clover  plowed  under  to  supply  the  nitro- 
gen, it  is  very  probable  that  abundance  of  potassium  would  have 
been  liberated  from  the  soil. 

Potatoes  draw  heavily  upon  potassium,  and  ultimately,  on  level 
land  which  neither  receives  deposits  from  overflow  nor  loses  par- 
tially exhausted  soil  by  erosion,  potassium  must  become  so  defi- 
cient as  to  limit  the  crop  yield,  even  with  the  best  efforts  to  main- 
tain adequate  supplies  of  active  organic  matter;  but  the  total 
supply  of  potassium  in  2  million  pounds  of  this  Ohio  soil  is  suffi- 
cient for  200  bushels  of  potatoes  every  year  for  more  than  500 
years,  and  the  land  has  sufficient  surface  drainage  to  insure  some 
soil  erosion. 

Another  series  of  long-continued  and  very  valuable  experiments 
have  been  conducted  by  the  Ohio  Station  on  the  Strongsville  experi- 
ment farm,  on  a  quite  different  type  of  soil,  of  nearly  level  topog- 
raphy, higher  clay  content,  and  less  perfect  physical  condition. 
The  surface  acre-foot  of  Wooster  soil  contains,  as  a  general  average, 
about  2770  pounds  of  nitrogen,  1700  pounds  of  acid-soluble  phos- 
phorus, and  7310  pounds  of  acid-soluble  potassium,  while  the 
corresponding  figures  for  the  Strongsville  soil  are  6520,  1700,  and 
6300.  Thus  the  Strongsville  soil  averages  more  than  twice  as  rich 
in  nitrogen,  but  somewhat  poorer  in  acid-soluble  potassium,  while 
the  phosphorus  content  is  practically  equal  in  the  two  soils. 

Table  84  gives  the  average  results  obtained  from  a  series  of  5- 
year  rotation  experiments  (1896-1897-1898  to  1907).  The  plant- 
food  materials  are  440  pounds  of  sodium  nitrate  (and  50  pounds 
of  dried  blood),  320  pounds  of  acid  phosphate,  and  260  pounds 
of  potassium  chlorid.  (One  plot  (No.  12)  receives  680  pounds 
of  sodium  nitrate.) 

The  more  marked  effect  of  phosphorus  on  the  Strongsville  soil 
is  doubtless  due  to  the  larger  supply  of  organic  matter,  the  decom- 
position of  which  tends  to  furnish  nitrogen  and  liberate  potassium. 
As  an  average,  the  crops  from  the  best-yielding  plots  have  removed 


452     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

30  pounds  of  phosphorus  during  the  five  years,  or  50  per  cent  more 
than  was  applied. 

TABLE  84.   EXPERIMENTS  AT  STRONGSVILLE,  OHIO 
Data  per  Acre  for  Five-year  Rotation:    Increase  Only,  except  as  Noted 


CLOV- 

TIMO- 

CORN, 

OATS, 

ER, 

THY, 

PLANT  FOOD  APPLIED 

I2-YR. 

AVERAGE 

II-YR. 
AVERAGE 

AVER- 

IO-YR. 
AVER- 

IO-YR. 
AVER- 

(Bu.) 

(Bu.) 

AGE 

AGE 

(Tons) 

(Tons) 

Nitrogen,  76  Ib  

1.18 

-.OS 

—  .24 

.08 

.OI 

Phosphorus,  20  Ib  

QCl 

IO.OQ 

7.14 

•  4S 

.16 

Potassium,  108  Ib  

.20 

.41 

—  .1C 

.os 

—  .OI 

Nitrogen,  phosphorus  

10  46 

14.38 

0.72 

.  30 

.12 

Nitrogen,  potassium,      

I.4O 

2.24 

1.67 

.06 

—  .02 

Phosphorus,  potassium      

0  O4 

IO.  ^4 

8.04 

.34 

.17 

Nitrogen,  phosphorus,  potassium    .     . 

12.07 

14.69 

IO.2I 

•39 

•17 

Nitrogen,1  phosphorus,  potassium   .     . 

11.36 

14-51 

12.85 

.36 

.11 

Total  yield  from  untreated  land       .     . 

(26.94) 

(34.80) 

(5-62) 

(.68) 

(-75) 

'On  this  plot  114  Ib.  of  nitrogen;  otherwise  the  applications  were:  nitrogen, 
76  Ib. ;  phosphorus,  20  Ib. ;  and  potassium,  108  Ib. ;  per  acre,  in  five  years. 

In  general,  it  may  be  stated  that  the  plant  food  applied  in  the 
Ohio  experiments  produced  small  effects  the  first  few  years.  Thus, 
in  the  5-year  rotation  at  Wooster  the  largest  increase  in  corn  in 
1904  was  3.5  bushels  per  acre,  on  plot  21,  and  in  8  cases  out  of  20 
the  treated  plots  produced  lower  yields  than  the  untreated  control 
plots.  As  an  average  of  the  first  five  years,  phosphorus  (on  the 
No.  2  plots)  produced  increases  per  acre  as  follows:  corn,  4  bushels; 
oats,  3.5  bushels;  wheat,  3.1  bushels;  clover,  390  pounds ;  timothy, 
186  pounds.  These  are  about  one  half  the  effect  for  the  i5~year 
average,  as  will  be  seen  from  Table  82. 

From  a  consideration  of  the  Rothamsted  and  Pennsylvania 
data,  it  seems  probable  that  more  or  less  of  this  apparent  average 
increase  is  due  to  a  comparative  decrease  on  the  unfertilized  plots, 
although  the  time  is  too  short  since  the  Ohio  rotations  and  soil 
treatment  have  been  fully  under  way  to  make  trustworthy  averages, 
because  of  seasonal  variations;  for,  while  land  may  be  decreasing 
in  normal  productive  power,  a  few  favorable  seasons  following 
unfavorable  years  may  furnish  data  that  indicate  increasing  yields, 
as  in  the  Minnesota  experiments'ref erred  to  on  a  former  page. 


CHAPTER  XXII 

ILLINOIS   FIELD    EXPERIMENTS 

ASIDE  from  the  old  experiments  on  the  University  Farm,  the 
Illinois  field  experiments  have  been  in  progress  only  for  a  few  years, 
but  they  are  of  special  interest  and  value  because  they  are  conducted 
in  widely  separated  places  and  on  different  definite  soil  types  of 
great  extent  and  importance. 

Brown  silt  loam  constitutes  the  most  common  prairie  soil  in  the 
middle  and  upper  Illinoisan,  pre-Iowan,  and  early  Wisconsin 
glaciations,  and  is  found  also  in  the  lowan  and  late  Wisconsin.  It 
is  called  "  the  ordinary  prairie  land  "  by  farmers  throughout  the 
corn  belt,  extending  from  Mattoon,  Illinois,  into  Wisconsin,  and 
from  north-central  Indiana  into  Nebraska  and  South  Dakota. 

While  the  different  brown  silt  loams  are  similar  in  many  respects, 
they  differ  somewhat  in  chemical  composition,  varying  with  age 
or  formation  of  the  different  areas,  and  it  is  noteworthy  that  in 
the  older  soil  areas  the  brown  silt  loam  is  either  no  longer  repre- 
sented (as  in  the  lower  Illinoisan  glaciation),  or  it  is  replaced  to 
some  extent  by  a  type  of  soil  intermediate  in  character  and  value 
between  brown  silt  loam  and  gray  silt  loam  on  tight  clay.  This 
intermediate  type  is  well  developed  in  places  in  the  southern  part 
of  the  middle  Illinoisan  glaciation  and  in  the  western  part  of  the 
upper  Illinoisan,  but  it  is  only  one  of  many  minor  types  whose 
exact  location  requires  a  detail  soil  survey. 

The  top  soil  of  the  brown  silt  loam  consists  of  a  friable  dark- 
colored  and  fairly  uniform  soil  to  a  depth  of  1 6  to  20  inches,  with 
appreciably  less  organic  matter  at  the  lower  depth.  Below  the  top 
soil,  from  16  or  20  inches  to  40  inches  and  more,  is  the  yellow,  silty 
subsoil,  somewhat  less  porous  or  friable  than  the  top  soil,  but  not 
very  compact. 

This  soil  and  subsoil  have  great  capacity  to  absorb  and  retain 
water  from  heavy  rains,  and  later  to  deliver  the  moisture  to  grow- 

453 


454    INVESTIGATION   BY   CULTURE  "EXPERIMENTS 

ing  crops  as  needed.  In  other  words,  the  crops  growing  on  brown 
silt  loam  soils  are  enabled  to  withstand  drouths  that  would  pro- 
duce very  severe  damage  on  such  a  soil  as  the  lower  Illinoisan 
gray  silt  loam  on  tight  clay.  Of  course  even  the  brown  silt  loam 
becomes  much  less  absorbent  and  less  retentive  of  moisture  where 
the  surface  soil  is  allowed  to  become  deficient  in  humus. 

As  a  general  average  (the  late  Wisconsin  being  disregarded) 
the  brown  silt  loams  contain  in  the  surface  soil  of  an  acre  (2  mil- 
lion pounds)  about  4800  pounds  of  nitrogen,  1200  pounds  of  phos- 
phorus, and  34,000  pounds  of  potassium,  amounts  which,  if  they 
could  be  drawn  upon  at  will,  would  furnish  the  nitrogen  for  100 
bushels  of  corn  (grain  only)  every  year  for  48  years,  the  phosphorus 
for  70  years,  or  the  potassium  for  1790  years.  For  four  tons  per 
acre  of  clover  hay  each  year,  the  nitrogen,  if  drawn  only  from  the 
surface  soil,  would  be  sufficient  for  30  years,  the  phosphorus  for 
60  years,  and  the  potassium  for  280  years. 

These  data  are  for  very  large  crops,  and  take  into  account  only 
the  plant  food  in  the  surface  soil  to  a  depth  of  6f  inches,  but  these 
crops  are  not  loo  large  to  try  to  raise,  and  the  fertility  of  the  surface 
soil  must  be  maintained  if  we  are  to  maintain  a  permanent,  profit- 
able agriculture.  We  may  reduce  the  crop  yields  to  the  lowest 
limit  of  profit  on  land  valued  at  $150  to  $200  an  acre,  but  still  the 
absolute  limit  in  years  is  short  for  the  nitrogen  and  the  phosphorus 
in  this  most  common  prairie  soil  of  the  corn  belt ;  and,  if  such  crops 
of  corn  and  clover  as  are  mentioned  above  had  been  removed  from 
this  land  from  the  time  Columbus  discovered  America  until  now, 
every  pound  of  phosphorus  contained  in  the  soil  to  a  depth  of  four 
feet  would  have  been  required  for  the  crops  grown. 

So  far  as  the  author  has  been  able  to  learn,  the  oldest  soil  experi- 
ment field  in  the  United  States  with  an  authentic  record  of  its 
origin  and  with  a  present  continuation  of  the  experiments  origi- 
nally inaugurated  is  on  the  campus  of  the  University  of  Illinois, 
or  rather  it  is  surrounded  by  the  University  campus.  In  the 
biennial  report  for  1879  and  1880,  on  page  232,  and  under  date  of 
March  10,  1880,  is  the  following: 

"The  Farm  Committee  then  submitted  the  following  report: 

"To  the  Hon.  Board  of  Trustees  of  the  Illinois  Industrial  University: 


ILLINOIS   FIELD    EXPERIMENTS  455 

"Your  committee  beg  leave  to  submit  the  following  recommendations  from 
the  Professor  of  Agriculture  in  regard  to  experiments  for  the  coming  season :  .  .  . 

"Fifth.  The  formal  commencement  of  what  is  designed  to  be  a  long-con- 
tinued experiment  to  show  the  effect  of  rotation  of  crops,  contrasted  with  con- 
tinuous corn-growing,  with  and  without  manuring,  and  also  the  effect  of 
clover  and  grass  in  a  rotation.  A  commencement  was  made  last  year,  and  we 
are  fortunate  in  having  a  piece  of  land  more  than  usually  well  adapted  for  such  a 
test. 

"  The  report  was  approved,  and  its  recommendation  concurred  in." 

Thus,  these  oldest  rotation  experiments,  begun,  according  to  the 
official  records,  by  Prof essor  George  E.  Morrow,  in  1879,  completed 
a  record  of  thirty-one  years  in  1909.  Fortunately,  these  plots  are 
located  on  the  typical  brown  silt  loam  soil  of  the  corn-belt  prairie 
land. 

In  Bulletin  13  of  the  Illinois  Agricultural  Experiment  Station, 
published  in  1891  and  signed  by  Professor  Morrow,  the  state- 
ment is  made  that  from  the  beginning  of  these  experiments  plot 
No.  3  had  "  been  in  corn  continuously,"  that  plot  No.  4  had 
been  "  in  corn  and  oats  alternately,"  and  that  plot  No.  5  had 
"  had  this  rotation:  corn,  2  years;  oats,  i  year;  meadow  (clover, 
timothy,  or  both),  3  years."  The  records  also  state  that  these 
plots  had  received  "  no  manure  or  commercial  fertilizers  of  any 
kind." 

The  series  originally  contained  seven  other  plots,  and  included  a 
limited  use  of  commercial  fertilizers  and  farm  manure,  and  other 
rotation  systems.  All  but  three  of  the  original  plots  have  been 
taken  for  campus  or  buildings. 

The  Experiment  Station  was  established  in  1888,  and  in  the  re- 
ports made  by  Professor  Morrow  and  his  assistants  relating  to 
these  experiments  and  published  in  1888  to  1894  there  is  no  record 
of  crop  yields  previous  to  1888.  The  most  important  thing,  per- 
haps, is  the  record  that  the  crop  systems  were  followed  during  those 
early  years. 

Since  1888  these  crop  systems  for  the  three  plots  mentioned  have 
been  essentially  maintained,  with  the  modification  on  plot  No.  5 
during  the  later  years  of  adopting  the  more  simple  rotation  of 
corn,  oats,  and  clover,  one  each  year.  From  the  recorded  state- 
ments and  the  existing  knowledge  it  is  safe  to  say  that  all  crops 


456    INVESTIGATION   BY    CULTURE   EXPERIMENTS 

have  been  removed,  including  the  grain,  hay,  straw,  and  corn 
fodder,  from  1879  to  the  present  time,  but  records  of  yields  are 
lacking  in  some  cases. 

Originally,  these  plots  were  one  half  acre  each  in  size,  being  5 
rods  wide  (north  and  south)  by  16  rods  long  (east  and  west),  but 
in  1904,  because  of  the  enlargement  of  the  University  campus,  it 
became  necessary  to  reduce  the  length  to  9  rods  in  the  central 
part  of  the  original  plots.  At  the  same  time  one-half  rod  division 
strips  were  established  between  the  plots,  also  a  one-fourth  rod 
cultivated  or  cropped  protecting  border  around  the  plotted  area, 
and  each  of  the  three  plots  was  also  divided  in  four  quarters  by 
half-rod  division  strips  through  the  center  in  both  directions. 
Thus,  from  each  of  the  original  plots  four  plots  of  one-twentieth 
acre  each  have  been  formed,  with  half-rod  protecting  strips.  In 
each  case  the  two  plots  on  the  north  are  continued  as  a  duplicate 
test  of  the  original  system,  without  the  use  of  manure  or  commercial 
fertilizers,  while  the  two  plots  on  the  south  are  cropped  the  same, 
but  they  are  now  being  improved  by  such  applications  of  farm 
manure  as  can  well  be  made  from  the  crops  grown,  by  the  use  of 
legume  catch  crops,  applications  of  ground  limestone  to  correct 
possible  soil  acidity,  and  by  the  use  of  phosphorus,  applied  for  each 
year  in  the  rotation  in  200  pounds  of  steamed  bone  meal  (on  the 
east  plot),  or  in  600  pounds  of  rock  phosphate  (on  the  west  plot), 
per  acre. 

The  original  plot  numbers  are 'retained,  the  untreated  north 
part  being  known  as  3N,  4N,  and  5N;  and  the  treated  south  part 
as  38,  48,  and  58,  respectively;  and  to  each  of  these  may  be  added 
W  or  E  to  designate  the  west  or  east  half. 

InTable  85  are  recorded  the  yields  of  these  old  plots  for  the  last 
twenty-two  years,  from  1888  to  1909,  including,  since  1904,  for  each 
rotation  system,  the  average  of  the  untreated  duplicates  and  of 
the  treated  parts. 

Seasonal  influences  are  so  great  that  no  very  satisfactory  com- 
parison can  be  made  between  different  years  for  the  sake  of  deter- 
mining the  effect  of  the  different  systems  upon  the  productive 
power  of  the  soil, 'and  the  thorough  underdrainage  provided  for 
in  1904  must  be  expected  to  markedly  increase  the  crop  yields  in 
subsequent  seasons  of  excessive  rainfall,  such  as  1907,  for  example, 


ILLINOIS   FIELD    EXPERIMENTS 


457 


TABLE  85.   CROP  YIELDS  PER  ACRE  FROM  THE  OLDEST  ILLINOIS  EXPERIMENT 
PLOTS:    URBANA  SOIL  EXPERIMENT  FIELD 


YEARS 

Son.  TREATMENT  APPLIED 

CORN 
EVERY 
YEAR 

TWO-YEAR 
ROTATION 

THREE-YEAR 
ROTATION 

Corn 
(Bu.) 

Corn 
(Bu.) 

Oats 
(Bu.) 

Corn 
(Bu.) 

Oats 
(Bu.) 

Clover 
(Tons) 

1879-87 
1888 
1889 
1890 
1891 

54-3 
43-2 
48.7 
28.6 

49-5 

48.6 

37-4 

4.04 

I-Si 

1.46 

54-3 
33-2 

None   

1892 

1893 
1894 

33-  1 
21.7 

34-8 

37-2 

67.6 
34-1 

29.6 

None   .     :     

57-2 

65.1 

1895 
1896 
I897 

42.2 
62.3 
40.1 

41.6 

22.2 

34-5 

None   

47.0 

1898 
1899 
1900 

18.1 
50.1 
48.0 

None 

44.4 

53-5 

None   

4i-5 

1901 
1902 
1903 

None   

23-7 
60.2 
26.0 

33-7 

56.3 

34-3 

54-6 

None   

3,-vQ 

I.  II 

1904 
1904 

1905 

I9°S 
1906 
1906 

N.  ^  None     
o   i  f  Legume/  manure,2  | 
'^{lime,  phosphorus2  J 
N  \  None 

21.5 
17.1 
24.8 

3i-4 
27.1 

35-8 

17-5 
25-3 

55-3 

72.7 

50.0 
44-9 

42.3 
50.6 



S.  ^,  Lgm.,  mnr.,  lime,  phos. 
N  \  None 

34-7 
52.5 

1-43  3 
r.743 

S.  %,  Lgm.,  mnr.,  lime,  phos. 

1907 
1907 
1908 
1908 
1909 
1909 

N  \  None 

29.0 
48.7 
13-4 
28.0 
26.6 
31-6 

47-8 
87.6 

80.5 
93-6 

S.  \  ,  Lgm.,  mnr.,  lime,  phos. 
N  ^   None 

32.9 

45-° 

4O.O 

44-4 

S.  5,  Lgm.,  mnr.,  lime,  phos. 
N  J  None 

33-0 
64.8 

•65 

1.74 

S.  £,  Lgm.,  mnr.,  lime,  phos. 

1910 
1910 
1911 
1911 
1912 
1912 

N.  £,  None 

35-9 
54-6 

21.8 

31-5 
43-2 
64.2 

33-8 
59-4 

58.6 
83-3 

S.  J,  Lgm.,  mnr.,  lime,  phos. 
N  5  None 

28.6 

46.3 

20.5 
37-9 

S.  J,  Lgm.,  mnr.,  lime,  phos. 

N.  |,  None 

55-0 
81.0 

i-354 
i-7o4 

S.  £,  Lgm.,  mnr.,  lime,  phos. 

1  Legume  catch  crops  first  grown  in  1904  to  benefit  1905  crops. 

2  Manure  and  phosphorus  first  applied  to  plot  58  for  1904  crop,  but  to  plots  38 
and  4$  for  1905  crop.         3Cowpea  hay;  the  clover  failed.         4  Soy-bean  hay. 


458    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

as  compared  with  previous  years.  Thus,  on  the  continuous  corn 
plot  the  yield  was  18.1  bushels  in  1898  and  60.2  bushels  four  years 
later,  and  the  largest  recorded  corn  yield  in  the  corn-oats-clover 
rotation  was  80.5  bushels  in  the  wet  season  of  1907. 

A  fair  comparison  between  different  systems  can  usually  be  made 
in  the  same  years,  and  the  change  in  productive  power  under  any 
system  can  best  be  ascertained  by  comparing  the  results  from  these 
old  experiments  with  those  from  newer  experiments,  as  shown  in 
Table  86,  when  the  effect  of  sixteen  years'  cropping  can  be  noted. 
Every  plot  in  the  newer  experiments  produced  more  than  75 
bushels  of  corn  per  acre  in  1896,  and  the  average  in  1897  was  about 
70  bushels.  Upon  these  facts  is  based  the  assumption  that  all  of 
the  older  plots  originally  produced  70  bushels  or  more  per  acre. 

It  is  apparent  that  the  legume  catch  crops  (chiefly  cowpeas) 
seeded  in  the  corn  decrease  the  yield  for  the  first  year  at  least,  as 
shown  in  1904  on  plot  3  and,  even  in  spite  of  the  light  manuring, 
on  plot  4  in  1905. 

The  general  effect  of  the  system  of  soil  improvement  adopted  for 
the  south  half  of  each  of  these  old  plots  is  already  very  marked,  an 
increase  of  40  bushels  of  corn  per  acre  being  secured  in  1907  from  the 
treatment  on  plot  4,  where  the  most  marked  effect  is  to  be  expected 
because  no  clover  or  other  legumes  had  been  grown  previous  to 
1904  in  this  rotation,  and  the  frequent  change  from  corn  to  oats  has 
helped  to  avoid  the  development  of  corn  insects. 

Table  86  gives,  for  comparison,  three-year  averages  for  corn, 
including  the  1901-7  corn  crops  grown  in  the  three-year  rotation  on 
the  old  field. 

As  an  average  of  the  three  years  where  corn  has  been  grown  every 
year,  the  yield  has  been  27  bushels  in  the  29-year  experiments  and 
35  bushels  in  the  13-year  experiments.  The  lesson  of  these  experi- 
ments is  that  12  years  of  cropping  where  corn  follows  corn  every 
year  reduces  the  yield  from  more  than  70  bushels  to  35  bushels 
per  acre,  after  which  the  decrease  is  much  less  rapid,  amounting 
to  only  8  bushels'  reduction  during  the  next  16  years.  Undoubtedly 
the  rapid  reduction  during  the  first  12  years  of  continuous  corn- 
growing  is  due  in  large  part  to  the  destruction  of  the  more  active 
decaying  organic  matter,  resulting  ultimately  in  insufficient  libera- 
tion of  plant  food  within  the  feeding  range  of  the  corn  roots. 


ILLINOIS   FIELD   EXPERIMENTS 


459 


TABLE  86.    COMPARABLE  CORN  YIELDS  FROM  THE  UNIVERSITY  OF  ILLINOIS 
EXPERIMENT  FIELD  AT  URBANA:   TYPICAL  BROWN  SILT  LOAM  PRAIRIE 

Three-year  Averages:  Bushels  per  Acre 


CROP  YEARS 

CROP  SYSTEM 

13-  YEAR 
EXPERIMENTS 

29-  YEAR 
EXPERIMENTS 

IQCX.  —6,  —7 

Corn  every  year  

^  bu. 

27  bu. 

IQO3.  —  <\.  ~7 

Corn  and  oats    

62  bu. 

46  bu. 

1901,  -4,  -7 

Corn,  oats,  clover  .... 

66  bu. 

58  bu. 

AVERAGE  OF  THREE  CORN  CROPS  IN  CORN-OATS-CLOVER  ROTATION 


GRAIN  FARMING 

LIVE-STOCK 

CROP  YEARS 

SPECIAL  TREATMENT 

WITH  CROP 

FARMING  WITH 

RESIDUES 

FARM  MANURE 

IQO2.  —3.  —4 

None    

77.4 

Gain 

75  3 

Gain 

IQO2,  —  ?,  —4 

Lime    

78.4 

80.8 

I.O 

e.e 

1902,  -3,  -4 

Lime,  phosphorus       .... 

88.0 

10.6 

88.8 

13-5 

1902,  -3,  -4 

Lime,  phosphorus,  potassium  . 

90.1 

12.7 

9°-5 

15.2 

TOO?      —6     —7 

None 

68  <; 

80  c 

IQCX,  -6,  —7 

Lime    

72.3 

3  8 

ouo 
848 

A    1 

1005,  -61  ~7 

Lime,  phosphorus       .... 

90.4 

21.9 

93-2 

12.7 

1905,  -6,  -7 

Lime,  phosphorus,  potassium  . 

93-8 

25-3 

95-6 

15-1 

TfloH     —  O     —TO 

None 

CT  C 

IOo8,  —  0,  —  IO 

Lime    

OXO 

q8  i 

66 

74  O 

s  6 

1908,  -9,  -io 

Lime,  phosphorus       .... 

83.8 

32.3 

86.6 

17-3 

1908,  -9,  -io 

Lime,  phosphorus,  potassium  . 

86.7 

35-2 

90.9 

21.  6 

Where  corn  is  followed  by  oats  in  a  2-year  rotation  the  average 
yield  of  the  three  crops  of  corn  is  46  bushels  in  the  29-year  experi- 
ments, whereas  in  the  13-year  experiments  the  average  yield  for 
the  same  three  years  is  62  bushels  of  corn  per  acre.  In  this  case  the 
destruction  of  humus  is  less  rapid,  and  the  development  of  the  corn 
insects  is  discouraged  by  changing  to  oats  every  other  year,  so  that 
the  decrease  in  yield  is  less  marked  during  the  early  years,  although 
the  reduction  continues  persistently  with  passing  years.  During 
the  first  ii  years  the  yield  decreased  from  more  than  70  bushels 
to  62,  and  the  next  16  years  show  a  further  reduction  of  16 
bushels. 


460    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

With  the  3-year  rotation  corn  is  grown  for  one  year,  followed 
by  oats  with  clover  seeding  the  second  year,  and  clover  alone  the 
third  year.  During  the  first  ten  years  under  this  system  the  yield 
of  corn  has  decreased  from  more  than  70  bushels  to  66,  and  during 
the  next  16  years  the  yield  has  further  decreased  to  58  bushels,  the 
average  reduction  being  only  one-half  bushel  a  year.  In  this  sys- 
tem the  most  marked  reduction  in  crop  yields  has  not  yet  appeared, 
although  it  must  be  expected  in  the  future  because  the  clover  crop 
is  already  beginning  to  fail  on  the  oldest  field,  even  in  seasons  when 
clover  succeeds  well  on  newer  land  under  the  same  crop  rotation. 
When  clover  fails,  cowpeas  are  substituted  for  that  year  on  that 
field,  which  thus  provides  a  legume  crop  and  preserves  the  3-year 
rotation. 

In  the  lower  part  of  Table  86  (third  column)  are  included  the 
average  yields  of  corn  for  the  last  three  years  in  a  system  of  grain 
farming,  in  a  3-year  rotation  of  corn,  oats,  and  clover.  This 
system,  when  fully  under  way,  provides  that  the  corn  shall  be  husked 
and  the  stalks  disked  down  in  preparation  for  the  seeding  of  oats 
and  clover  the  second  year.  In  harvesting  the  oats,  as  much  straw 
as  possible  is  left  in  the  stubble,  which  may  be  mowed  later  in  the 
summer  to  prevent  the  seeding  of  the  clover  or  weeds.  In  the 
spring  of  the  third  year  the  clover  is  mowed  once  or  twice  before  the 
usual  haying  time  and  left  lying  on  the  land.  The  seed  crop,  if 
successful,  is  harvested  with  a  hay  buncher  attached  to  the  mower, 
or  in  any  other  way  to  avoid  raking,  and  afterward  the  threshed 
clover  straw  and  oat  straw  (or  at  least  as  much  as  is  practicable) 
are  returned  to  the  land,  all  of  this  accumulated  organic  matter 
to  be  plowed  under  for  the  following  corn  crop,  which  begins  the 
next  rotation.  In  addition  to  this,  catch  crops  of  annual  legumes, 
such  as  cowpeas,  may  be  seeded  in  the  corn  at  the  time  of  the  last 
cultivation  and  disked  in  the  next  spring  with  the  corn  stalks. 
If  biennial  or  perennial  legumes  are  used  as  catch  crops,  the  corn 
ground  may  be  plowed  for  oats.  (This  is  a  practice  of  doubtful 
advantage  where  the  corn  is  rank.) 

The  corn  yields  reported  for  this  system  in  Table  86  were  secured 
where  the  system  was  not  fully  under  way,  the  legume-catch  crops 
being  the  only  organic  matter  returned  to  the  soil,  aside  from  the 
residues  necessarily  left,  except  for  the  last  crop  rotation.  By 


ILLINOIS   FIELD    EXPERIMENTS  461 

using  three  different  fields  for  this  rotation,  every  crop  may  be 
grown  every  year,  and  the  yields  of  corn  reported  are  true  three- 
year  averages. 

With  no  special  soil  treatment  aside  from  crop  residues  and  catch 
crops,  the  yield  of  corn  for  1908,  1909,  and  1910  averaged  52  bushels. 
Where  the  equivalent  of  ^  ton  per  acre  of  ground  limestone  was 
applied  (five  years  before)  the  corn  has  yielded  58  bushels  per  acre; 
and,  with  the  phosphorus  added  for  six  years  at  the  rate  per  annum 
of  25  pounds  per  acre  of  the  element  phosphorus  (in  200  pounds  of 
steamed  bone  meal)  the  average  yield  of  corn  has  been  84  bushels 
per  acre  for  the  last  three  years.  The  yearly  addition  of  42  pounds 
of  potassium  in  100  pounds  of  potassium  sulfate  has  further  in- 
creased the  yield  to  87  bushels. 

Under  the  heading  "  Live-stock  Farming,"  in  Table  86,  are  re- 
corded the  average  yields  of  corn  secured  during  the  same  three 
years  where  farm  manure  has  been  applied  to  the  clover  ground 
to  be  plowed  under  for  corn.  The  plan  of  this  system  is  to  remove 
all  crops  from  the  land  as  usually  harvested,  including  the  corn 
and  stover,  oats  and  straw,  and  both  first  and  second  crops  of 
clover.  The  amounts  of  manure  applied  to  the  different  plots  are 
determined  by  the  crop  yields  secured  during  the  previous  rotation. 
While  the  system  of  cropping  followed  during  the  16  years  on  these 
plots,  and  on  those  just  described  under  "  Grain  Farming,"  has 
been  approximately  equivalent  to  a  three-year  rotation  of  corn, 
oats,  and  clover,  the  applications  of  manure  have  been  made  only 
for  the  last  6  years,  from  1905  to  1910.  If  the  average  yields  are 
decreasing  on  plots  that  receive  only  the  amounts  of  manure  that 
can  be  produced  in  practice  from  the  crops  grown,  then  the  appli- 
cations of  manure  must  also  be  reduced  on  such  land ;  whereas  if 
the  crop  yields  are  increasing  where  both  manure  and  phosphorus 
are  applied,  then  the  applications  of  manure  for  such  plots  may  be 
increased  in  direct  proportion. 

Where  manure  alone  has  been  used  in  this  rotation,  the  com  has 
averaged  69  bushels  per  acre  for  the  three  years ;  with  lime  added, 
the  average  is  75  bushels;  with  lime  and  phosphorus,  the  manured 
land  has  averaged  87  bushels  of  corn,  and  this  was  increased  to  91 
bushels  by  adding  potassium. 

While  potassium  has  usually  made  some  increase  in  crop  yields 


462     INVESTIGATION  BY   CULTURE   EXPERIMENTS 

on  these  fields,  it  has  not  nearly  paid  its  cost.  The  most  profitable 
yields  are  the  88  bushels  in  grain  farming  or  the  90  bushels  in 
the  live-stock  system  (9-year  averages).  The  effect  of  limestone 
has  already  been  sufficiently  uniform  to  recommend  its  use  on 
this  soil,  and  marked  profit  has  resulted  from  the  addition  of 
phosphorus,  which  is  applied  in  sufficient  amount  actually  to  en- 
rich the  land,  and  not  as  a  stimulant.  Phosphorus  has  been  ap- 
plied since  1902. 

Table  87  gives  results  obtained  during  seven  years  (1902  to  1908) 
from  the  Sibley  soil  experiment  field,  located  in  Ford  County,  on 
typical  brown  silt  loam  prairie  of  the  Illinois  corn  belt. 

TABLE  87.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:  SIBLEY  FIELD 


BROWN  SILT  LOAM  PRAIRIE,  EARLY 
WISCONSIN  GLACIATION 

CORN, 

IO02 

CORN, 
1003 

OATS, 
1004 

WHEAT, 
1005 

CORN, 
1006 

CORN, 
1907 

OATS, 
1908 

Plot 

Soil  Treatment  Applied 

Bushels  per  Acre 

IOI 

102 

None   

57-3 
60.0 

5°-4 

54-o 

74-4 
74-7 

29-5 

31-7 

36-7 
39-2 

33-9 
38.9 

25-9 

24-7 

Lime    

I03 
IO4 
I°5 

Lime,  nitrogen  .... 
Lime,  phosphorus  .     .     . 
Lime,  potassium     .     .     . 

6o.c 
61.3 
56.0 

54-3 
62.3 

4.9-9 

77-5 
92-5 
74-4 

32.8 

36-3 
30.2 

41.7 
44.8 
37-5 

48.1 
43-5 
34-9 

36-3 
25.6 

22.2 

1  06 
107 

108 

Lime,  nitrogen,  phosphorus 
Lime,  nitrogen,  potassium 
Lime,  phosphorus,    potas- 
sium       

57-3 
53-3 

58.7 

69.1 
5i-4 

60.9 

88.4 
75-9 

80.0 

45-2 
37-7 

39-8 

68.5 
39-7 

4i-5 

72-3 
Si-i 

39-8 

45-6 
42.2 

27.2 

109 
no 

Lime,  nitrogen,  phosphorus, 
potassium  

58.7 
60.0 

65-9 
60.  i 

82.5 
85.0 

48.0 
4S.5 

69-5 
63-3 

80.  i 
72-3 

52.8 

44.1 

Nitrogen,  phosphorus,  po- 
tassium       

The  standard  applications  for  this  and  other  Illinois  soil  experi- 
ments are  100  pounds  of  nitrogen  (in  dried  blood),  25  pounds  of 
phosphorus  (in  steamed  bone  meal) ,  and  42  pounds  of  potassium  (in 
potassium  sulfate),  per  acre  per  annum,  but  the  phosphorus  and 
potassium  are  usually  applied  in  correspondingly  heavier  applica- 
tions once  for  the  rotation. 

It  is  not  necessary  to  take  space  here  for  a  complete  discussion 
of  the  data  in  Table  87. 

Previous  to  1902  this  land  had  been  cropped  with  corn  and  oats 


ILLINOIS   FIELD    EXPERIMENTS  463 

for  many  years  under  a  system  of  tenant  farming,  and  the  soil  had 
become  somewhat  deficient  in  active  humus.  While  phosphorus 
was  the  limiting  element  of  plant  food,  the  supply  of  nitrogen  be- 
coming available  annually  was  but  little  in  excess  of  the  phosphorus, 
as  is  well  shown  by  the  corn  yields  for  1903  when  phosphorus  pro- 
duced an  increase  of  8  bushels,  nitrogen  without  phosphorus  pro- 
duced no  increase,  but  nitrogen  and  phosphorus  increased  the  yield 
by  15  bushels. 

After  six  years  of  additional  cropping,  however,  nitrogen  appeared 
to  become  the  limiting  element,  the  increase  in  1907  being  9  bush- 
els from  nitrogen  and  only  5  bushels  from  phosphorus,  while  both 
together  produced  an  increase  of  33  bushels  of  corn.  By  comparing 
the  corn  yields  for  the  four  years,  1902,  1903,  1906,  and  1907,  it 
will  be  seen  that  the  untreated  land  has  apparently  grown  less  pro- 
ductive, whereas  on  land  receiving  both  phosphorus  and  nitrogen 
the  yield  has  appreciably  increased,  so  that  in  1907,  when  the  un- 
treated rotated  land  produced  only  34  bushels  of  corn  per  acre,  a 
yield  of  72  bushels,  or  more  than  twice  as  much,  was  produced 
where  lime,  nitrogen,  and  phosphorus  had  been  applied,  although . 
these  two  plots  produced  exactly  the  same  yield  (57  bushels)  in 
1902.  While  the  actual  yields  might  be  quite  different  under  dif- 
ferent seasonal  conditions,  the  relative  and  increasing  differences 
between  the  plots  must  be  considered  as  representative  and  due 
to  the  difference  in  soil  treatment. 

By  comparing  plots  101  and  102,  and  also  109  and  no,  will  be 
seen  the  increase  by  lime,  suggesting  that  the  time  is  near  when 
lime  also  must  be  applied  to  these  brown  silt  loam  soils. 

Because  of  the  tremendous  importance  of  this  most  common  corn- 
belt  soil  to  American  agriculture  and  to  the  prosperity  of  the  na- 
tion, space  is  taken  to  insert  Table  88,  giving  all  of  the  results  thus 
far  obtained  from  the  Bloomington  soil  experiment  field,  which  is  • 
also  located  on  the  brown  silt  loam  prairie  of  the  Illinois  corn  belt. 
(Additional  data  are  inserted  on  page  475.) 

The  general  results  of  the  seven  years'  work  on  the  Bloomington 
field  tell  the  same  story  as  those  from  the  Sibley  field.  The  rota- 
tions differ  by  the  use  of  clover  and  cowpeas  in  1906,  and  in  dis- 
continuing the  use  of  commercial  nitrogen  after  1905,  on  the 
Bloomington  field,  in  consequence  of  which  phosphorus  without 


464 


TABLE  88.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:  BLOOMINGTON 

FIELD 


BROWN  SILT  LOAM  PRAIRIE,  EARLY 

CORN, 

CORN, 

OATS. 

WHEAT, 

CLOVER, 

CORN, 

CORN, 

WISCONSIN  GLACIATION 

IOO2 

1903 

1904 

1905 

1906 

1907 

1908 

Plot 

Soil  Treatment  Applied 

Bushels  or  Tons  per  Acre 

IOI 

None      

30.8 

63.0 

EJ4.8 

30.8 

.•7Q 

00.8 

4O  1 

102 

Lime      

37-0 

60.3 

60.8 

28.8 

.58 

63.1 

353 

IOT, 

Lime,  nitrogen  '  .     .     .     . 

35-i 

59-5 

69.8 

3°-5 

.46 

64-3 

36-9 

IO4 

Lime,  phosphorus     .     .     . 

41.7 

73-o 

72.7 

39-2 

1.65 

82.1 

47-5 

105 

Lime,  potassium  .... 

37-7 

56.4 

62.5 

33-2 

•51 

64.1 

36.2 

1  06 

Lime,  nitrogen,1  phosphorus 

43-9 

77.6 

85-3 

50.9 

2 

78.9 

45-8 

107 

Lime,  nitrogen/  potassium 

40.4 

58.9 

66.4 

29-5 

.Si 

64-3 

31.0 

108 

Lime,  phosphorus,  potassium 

50.1 

74.8 

70-3 

37-8 

2.36 

81.4 

57-2 

109 

Lime,  nitrogen,1  phosphorus, 

potassium     

52.7 

80.  o 

90-5 

5i-9 

2 

88.4 

58.1 

no 

Nitrogen,1    phosphorus,    po- 

tassium    

52-3 

73-  1 

71.4 

5i-i 

2 

78.0 

Si-4 

1  No  commercial  nitrogen  applied  after  1905. 

2  Clover  smothered  out  by  previous  very  heavy  wheat  crop.     After  the  clover 
hay  was  harvested,  all  ten  of  the  plots  were  seeded  to  cowpeas,  and  the  crop  was 
plowed  under  later  on  all  plots  as  green  manure  for  the  1907  corn  crop. 

nitrogen  (plot  104)  produced  nearly  as  large  an  increase  as  the 
increase  by  phosphorus  with  nitrogen  (plot  106) ;  whereas  on  the 
Sibley  field  phosphorus  with  nitrogen  (plot  106)  produced  more 
than  twice  as  large  an  increase  as  the  increase  by  phosphorus  with- 
out nitrogen. 

It  should  be  stated  that  a  draw  runs  near  plot  1 10  on  the  Bloom- 
ington  field,  and  the  crops  on  that  plot  are  sometimes  damaged  by 
overflow  or  imperfect  drainage.  Otherwise,  all  results  reported  in 
Tables  87  and  88,  including  more  than  150  tests,  are  considered 
trustworthy,  and  they  furnish  much  information  and  afford  many 
interesting  and  instructive  comparisons,  as,  for  example,  between 
plots  104  and  106  and  between  108  and  109  on  the  Sibley  field  where 
no  legumes  are  grown  in  the  rotation;  also,  between  plots  103  and 
106  and  between  107  and  109  on  both  fields. 

Wherever  nitrogen  was  provided  either  by  direct  application  or 
by  the  use  of  legume  crops,  the  addition  of  the  element  phosphorus 


ILLINOIS   FIELD    EXPERIMENTS  465 

produced  very  marked  increases,  the  average  value  being,  as  a 
rule,  more  than  double  its  cost  in  steamed  bone  meal,  the  form 
in  which  it  was  applied  to  these  fields.  On  the  other  hand,  the 
use  of  phosphorus  without  nitrogen  will  not  maintain  the  fertil- 
ity of  the  soil  (see  plots  104  and  106,  Sibley  field),  and  a  liberal 
use  of  clover  or  other  legumes  is  suggested  as  the  only  practical 
and  profitable  method  of  supplying  the  nitrogen,  the  clover  to  be 
plowed  under,  either  directly  or  as  manure,  preferably  in  connec- 
tion with  the  phosphorus  applied,  especially  if  raw  rock  phosphate 
is  used. 

From  the  best  treated  plots,  100  pounds  per  acre  of  phosphorus 
have  been  removed  from  the  soil  in  the  seven  crops.  This  is  equal 
to  10  per  cent  of  the  total  phosphorus  contained  in  the  surface 
soil  of  an  acre.  In  other  words,  if  such  crops  could  be  grown  for 
84  years,  they  would  require  as  much  phosphorus  as  the  total 
supply  in  the  surface  6|  inches  of  soil.  The  results  plainly  show, 
however,  that  without  the  addition  of  phosphorus  such  crops 
cannot  be  grown  year  after  year.  Where  no  phosphorus  was 
applied,  the  crops  removed  only  75  pounds  of  phosphorus  in  seven 
years,  or  nearly  1 1  pounds  a  year,  equivalent  to  almost  i  per  cent 
of  the  total  amount  (1260  pounds)  in  the  surface  soil.  (See  also 
Table  50,  giving  results  of  raw  rock  phosphate  on  brown  silt  loam.) 

The  yellow-gray  silt  loams  are  found  on  the  undulating  upland 
areas  that  are,  or  were  originally,  timbered.  The  topography 
varies  from  nearly  level  to  gently  rolling,  corresponding  to  the 
topography  of  the  brown  silt  loam  prairies.  The  yellow-gray  silt 
loam  varies  from  yellow  to  gray  in  the  surface,  and,  as  a  rule,  there 
is  more  or  less  "  gray  layer"  in  the  subsurface  (especially  in  the 
older  formations).  On  the  late  Wisconsin  glaciation,  the  loess 
covering  being  shallow,  glacial  material  containing  more  or  less 
gravel  is  frequently  found  in  the  subsoil  within  40  inches  of  the 
surface. 

As  shown  in  Table  15,  the  late  Wisconsin  yellow-gray  silt  loam 
(1034)  contains  in  the  surface  6|  inches  about  2900  pounds  of 
nitrogen,  800  pounds  of  phosphorus,  and  47,600  pounds  of  potas- 
sium. Compared  with  the  more  productive,  more  durable,  and 
more  valuable  soils  (as  the  early  Wisconsin  black  clay  loam), 
this  soil  is  very  poor  in  phosphorus  and  quite  low  in  humus  as 


466    INVESTIGATION   BY   CULTURE    EXPERIMENTS 

measured  by  the  nitrogen  or  organic  carbon,  while  it  is  extremely 
rich  in  potassium.1 

The  total  supply  of  phosphorus  in  the  plowed  soil  (6f  inches 
deep)  is  less  than  would  be  required  for  35  crops  of  corn  yielding 
100  bushels  of  grain  and  3  tons  of  stover,  while  the  total  nitrogen 
content  even  to  a  depth  of  40  inches  is  less  than  would  be  required 
for  60  such  crops,  or  for  less  than  90  if  only  the  grain  were  removed, 
although  the  total  potassium  to  a  depth  of  40  inches  is  sufficient 
to  meet  the  requirements  of  loo-bushel  crops  of  corn  every  year 
for  more  than  4  thousand  years,  or  for  more  than  16  thousand 
years  if  only  the  grain  is  removed.  Notwithstanding  these  positive 
facts,  based  upon  absolute  chemical  analysis,  showing  such  an 
enormous  supply  of  potassium  and  a  relatively  small  supply  of 
nitrogen,  the  addition  of  soluble  potassium  salts,  while  not  yielding 
profitable  results,  has  actually  produced  a  larger  average  increase 
than  has  been  produced  by  nitrogen  applied  in  dried  blood  on  the 
Antioch  soil  experiment  field  about  five  miles  from  the  Wisconsin 
line,  in  Lake  County,  Illinois,  on  the  late  Wisconsin  yellow-gray 
silt  loam,  thus  affording  a  good  illustration  of  the  fact  that  systems 
of  soil  treatment  for  permanent  agriculture  should  not  be  based 
solely  upon  previous  culture  experiments. 

This  soil  is  deficient  in  active  humus,  and  the  soluble  potassium 

1  It  is  appropriate  to  mention  in  this  connection  that  Doctor  A.  S.  Cushman 
of  the  United  States  Department  of  Agriculture  has  recently  emphasized  (Science 
(1905),  22,  838;  and  U.  S.  Dept.  of  Agr.  Bureau  of  Plant  Industry  Bulletin  104) 
the  possibility  of  using  powdered  granite  and  felspar  as  a  source  of  potassium 
for  fertilizing  purposes,  although  some  previous  experiments  with  felspar  (Svenska 
Mosskidturfor.  Tidskr.  (1903),  //,  360;  (1904),  18,  33,  73)  have  not  given  en- 
couraging results.  While  it  is  by  no  means  certain  that  granite  averaging  4  per 
cent  of  potassium  or  felspar  with  8  or  10  percent  of  potassium  may  not  be  used  with 
profit  under  some  conditions,  as  where  it  can  be  secured  as  waste  or  by-product  at 
very  low  cost  near  lands  actually  deficient  in  potassium,  it  is  worth  while  to  know 
that  at  $3  per  ton  for  powdered  granite  the  surface  20  inches  of  the  principal 
types  of  soil  in  the  late  Wisconsin  glaciation  already  contains  about  $6000  worth 
of  potassium  per  acre  in  the  form  of  finely  powdered  granitic  rock.  In  other 
words,  two  tons  of  this  soil  (or  three  tons  of  any  silt  loam  soil  in  the  Illinois  corn  belt) 
spread  over  an  acre  of  land  would  supply  as  much  potassium,  and  in  the  same  form, 
as  would  be  supplied  by  a  ton  of  average  powdered  granite. 

While  the  phosphorus  content  of  the  surface  soil  of  most  $150  Illinois  land  can 
be  doubled  by  investing  $25  to  $40  per  acre  in  raw  rock  phosphate  at  $7.50  per  ton, 
to  double  the  potassium  content  by  applying  powdered  granite  at  a  cost  of  only 
$3  a  ton  would  cost  from  $1200  to  $1800  per  acre. 


ILLINOIS   FIELD   EXPERIMENTS 


467 


salt  acts  in  large  part  at  least,  if  not  entirely,  as  a  soil  stimulant 
rather  than  as  plant  food.  As  already  shown  by  the  results  from 
Rothamsted,  other  soluble  salts  may  produce  the  same  effect. 

In  Table  89  are  given  the  results  of  seven  years'  work  on  the  An- 
tioch  soil  experiment  field. 


TABLE 


CROP  YIELDS  IN  SOIL  EXPERIMENTS:   ANTIOCH  FIELD 


SOIL 

YELLOW-GRAY   SILT    LOAM,    UNDULAT- 

PLOT 

ING  TIMBER  LAND:   LATE  WISCONSIN 

GRAIN,  BUSHELS  PER  ACRE 

No. 

GLACIATION 

Treatment  Applied 

IQO2, 

Corn 

1903, 

Corn 

1904, 

Oats 

Wheat 

1906, 

Corn 

1907, 

Corn 

1908, 
Oats 

IOI 

None       

44.8 

?,66 

17.8 

18  «; 

•2C   Q 

12  4. 

6c;6 

IO2 

Lime       

45-1 

38-9 

12.8 

10..  1 

31-5 

9-5 

61.6 

IO3 

Lime,  nitrogen      .          .... 

46.3 

40.8 

2.8 

17.8 

37-8 

6  \ 

60.3 

IO4 

Lime,  phosphorus      

SO.  I 

^3.6 

12.5; 

«.8 

^7.4 

17.4 

7O.  Q 

105 

Lime,  potassium  

48.2 

50.2 

9-7 

21.7 

34-9 

12.9 

62.5 

1  06 

Lime,  nitrogen,  phosphorus     . 

56.6 

62.7 

15-9 

15.2 

59-3 

20.9 

49.1 

107 

Lime,  nitrogen,  potassium      .     . 

52.1 

54-9 

10.3 

11.8 

39-o 

II.  I 

52.6 

108 

Lime,  phosphorus,  potassium 

60.7 

66.0 

19.7 

28.7 

59-i 

I8.3 

59-4 

109 

Lime,  nitrogen,  phosphorus,  po- 

tassium     

6l  2 

69  i 

21.  Q 

180 

6<  o 

31  4 

Cl   Q 

no 

Nitrogen,  phosphorus,  potassium 

59-7 

71.8 

37-2 

16.3 

66.3 

28.8 

55-9 

Plot  No.  i  is  naturally  better  land  than  the  others,  and  both  i 
and  10  serve  only  as  checks  against  the  lime  treatment.  They  are 
not  used  in  studying  the  effects  of  plant  food  applied. 

The  oats  crop  in  1904  and  the  1907  corn  crop  were  almost  fail- 
ures. The  low  yields  of  wheat  from  plots  3,  6,  7,  and  9,  in  1905, 
were  due  to  the  fact  that  the  wheat  on  these  nitrogen  plots  grew 
very  rank  and  lodged  badly  before  it  ripened.  The  straw  on  these 
plots  also  rusted  badly,  resulting  in  shriveled  and  light  grain.  The 
oats  also  lodged  badly  on  the  nitrogen  plots  in  1908. 

The  total  gains  for  seven  years  show  very  markedly  the  effects 
of  soil  treatment.  After  the  first  year  the  best  treated  plots  pro- 
duced about  twice  as  much  as  plot  2,  which  serves  properly  as  a 
check  plot,  to  which  no  nitrogen,  phosphorus,  or  potassium  is 
applied. 

Sand  soil  is  found  in  considerable  areas  in  Wisconsin  and  Michi- 


468     INVESTIGATION   BY   CULTURE   EXPERIMENTS 


gan  and  in  northern  Illinois,  Indiana,  and  Ohio,  sometimes  on  sand 
plains  and  also  in  sand  dunes  where  the  sand  has  been  blown  into 
ridges  varying  from  narrow  drifts  to  extensive  sand-hill  areas,  often 
covering  many  square  miles,  as  inTazewell,  Mason,  and  Kankakee 
counties,  in  Illinois. 

In  composition  this  soil  averages  about  1400  pounds  of  nitrogen, 
800  of  phosphorus,  and  31,000  pounds  of  potassium  in  the  surface 
6f  inches  (2^  million  pounds).  The  high  percentage  of  potassium 
shows  that  this  soil  is  not  a  pure  quartz  sand,  but  is,  to  a  consider- 
able extent,  of  granitic  origin. 

In  composition  this  soil  is  extremely  poor  in  nitrogen,  rich  in 
potassium,  and  fairly  well  supplied  with  phosphorus,  if  we  consider 
its  very  porous  character  and  the  very  deep  feeding  range  afforded 
to  plant  roots. 

The  Green  Valley  soil  experiment  field  is  located  on  sand-ridge 
soil  in  Tazewell  County,  Illinois.  The  soil  varies  from  a  very  sandy 
loam  to  a  slightly  loamy  sand  that  is  easily  drifted  by  the  wind  when 
not  protected  by  vegetation.  This  field  was  broken  out  of  pasture 
in  1902.  In  Table  90  are  reported  results  secured  in  six  years  from 
contiguous  and  comparable  plots  in  that  part  of  the  Green  Valley 
field  where  nitrogen  as  well  as  other  elements  is  supplied  in  commer- 
cial form. 

TABLE  90.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:   GREEN  VALLEY 

FIELD 


SAND-RIDGE  SOIL 

GRAIN,  BUSHELS  PER  ACRE 

SOIL 

PLOT 

No. 

Treatment  Applied 

IQO2, 

Corn 

1903, 

Corn 

1904. 

Oats 

1905, 

Wheat 

1906, 
Corn 

1907, 

Corn 

401 

None      

68  7 

5^3 

40-7 

T«3 

72.9 

7C.2 

402 

Lime      

68.2 

42.0 

35  -Q 

19.0 

I7.8 

2Q-5 

4O? 

Lime,  nitrogen     

686 

6"v4 

44-4 

23.5 

62.9 

•?8.9 

404 

Lime,  phosphorus     

30.  i 

24.0 

20.3 

16.7 

10.4 

17.  I 

405 

Lime,  potassium       

23.1 

20.  i 

i6.(j 

I6.5 

8.4 

12.8 

406 

Lime,  nitrogen,  phosphorus   .... 

57-4 

69.8 

51-  Q 

26.8 

70.8 

64.7 

407 

Lime,  nitrogen,  potassium      .... 

70.0 

72.9 

54-7 

36.5 

74.8 

73-6 

408 

Lime,  phosphorus,  potassium     .     .     . 

49.8 

39-6 

36-9 

13-7 

18.3 

27.7 

409 

Lime,  nitrogen,  phosphorus,  potassium 

69-5 

69.8 

47.8 

36.2 

66.4 

73-6 

410 

Nitrogen,  phosphorus,  potassium    .     . 

57-2 

66.1 

50.0 

26.5 

66.0 

71.9 

ILLINOIS   FIELD   EXPERIMENTS  469 

Plots  i  (especially)  and  2  in  this  series  were  naturally  more 
productive  than  the  other  plots,  it  being  the  regular  custom  oi  the 
Illinois  Station  to  use  the  most  productive  land  for  the  untreated 
check  plots  if  any  such  differences  are  apparent  when  the  field  is 
established,  as  was  the  case  in  this  instance.  Plot  i  serves  only  as  a 
check  against  the  lime  treatment,  and  the  average  of  plots  2,  4,  5, 
and  8  gives  a  more  reliable  basis  of  comparison  for  ascertaining 
the  effect  of  nitrogen. 

Potassium  is  evidently  the  second  limiting  element  in  this  soil 
where  decaying  organic  matter  is  not  provided,  but  the  limit  of 
potassium  is  very  far  above  the  nitrogen  limit. 

During  the  six  years  plot  7,  receiving  nitrogen  and  potassium, 
produced  291.3  bushels  of  corn  (averaging  72.5  bushels  a  year), 
54.7  bushels  of  oats,  and  36.5  bushels  of  wheat,  per  acre.  To  pro- 
duce the  increase  of  plot  7  over  plot  5  would  require  about  75  per 
cent  of  the  total  nitrogen  applied.  Thus,  there  has  been  a  loss  of 
25  per  cent  of  the  nitrogen  applied,  which  is  a  smaller  loss  than 
usually  occurs  where  commercial  nitrogen  is  used.  Without  doubt, 
larger  yields  would  have  been  produced,  especially  of  corn,  if  150 
or  200  pounds  of  nitrogen  per  acre  per  annum  had  been  used,  which 
would  have  increased  the  cost  of  nitrogen  to  $22.50  or  $30,  re- 
spectively, per  acre  each  year. 

It  need  scarcely  be  mentioned  that  commercial  nitrogen  is  used 
in  these  and  other  experiments  in  Illinois  only  to  help  discover  what 
elements  are  limiting  the  crop  yields.  It  should  never  be  purchased 
for  use  in  general  farming,  but,  if  needed,  secured  from  the  atmos- 
phere by  legume  crops  to  be  returned  to  the  soil  directly  or  in  ma- 
nure. 

On  three  other  series  of  plots  on  the  Green  Valley  soil  experi- 
ment field,  a  three- year  rotation  of  corn,  oats,  and  cowpeas  is  prac- 
ticed, every  crop  being  represented  every  year.  On  plots  receiv- 
ing lime  and  phosphorus  and  legume  crops,  as  green  manure,  the 
yield  of  corn  was  45.6  bushels  in  1906  and  67.8  bushels  in  1907, 
compared  with  70.8  bushels  and  64.7  bushels  with  lime,  phosphorus, 
and  nitrogen  on  plot  6  (see  Table  90)  and  with  10.4  bushels  and 
13.1  bushels  with  no  nitrogen  on  plot  4,  for  the  respective  years. 
On  other  plots  receiving  comparable  treatment,  where  lime,  phos- 
phorus, and  potassium  were  used  with  nitrogen-gathering  legume 


470     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

crops  as  green  manure,  the  corn  yields  in  the  three-year  rotation 
were  54.6  bushels  in  1906  and  51.5  bushels  in  1907,  compared  with 
66.4  bushels  and  73.6  bushels  on  plot  9  with  nitrogen  applied,  and 
compared  with  18.3  bushels  and  27.7  bushels  on  plot  8  with  no 
nitrogen  for  the  same  years. 

The  growing  of  legume  crops  and  the  use  of  farm  manure  (and 
possibly  limestone)  are  the  only  recommendations  made  for  the 
improvement  of  these  well-drained  sand  soils,  although  further 
tests  may  show  profit  from  potassium  until  more  organic  matter  is 
supplied.  As  a  rule,  clover  cannot  be  grown  successfully  on  this 
land,  but  cowpeas  and  soy  beans  are  well  adapted  to  such  soil,  and 
they  produce  very  large  yields  of  excellent  hay  or  of  grain  very 
valuable  for  feed  and  also  for  seed. 

Under  the  best  conditions,  with  good  preparation  and  heavy 
manuring,  alfalfa  can  be  grown  on  this  sand  soil,  more  than  five 
tons  of  alfalfa  hay  per  acre  in  one  year  having  been  grown  on  part 
of  the  Green  Valley  field.  Both  soy  beans  and  alfalfa  should  be 
inoculated  with  the  proper  nitrogen-fixing  bacteria. 

Heavy  applications  of  ground  limestone  also  may  be  especially 
beneficial  in  getting  alfalfa  started. 

(It  should  be  kept  in  mind  that  residual  sand  soils,  such  as  are 
found  in  the  Coastal  Plains  soil  province  in  the  South  Atlantic  and 
Gulf  States,  are,  as  a  rule,  very  deficient  in  mineral  plant  food,  as 
well  as  in  nitrogen.) 

Peaty  swamp  lands.  Peat  is  chiefly  of  two  kinds,  one  being  known 
as  moss  peat  and  the  other  as  grass  peat.  Moss  peat  consists 
largely  of  dead  and  decaying  sphagnum  moss,  and  grass  peat  of 
the  residues  of  coarse  swamp  grass,  sedge,  flags,  etc.  Probably 
most  of  the  beds  in  Ohio,  Indiana,  Illinois,  and  Iowa  are  grass  peat, 
although  there  is  some  moss  peat  in  northern  Illinois.  Indeed,  in 
the  detail  soil  survey  of  Lake  County,  Illinois,  one  swamp  of  several 
acres  was  found  where  the  sphagnum  moss  is  still  growing  luxuri- 
antly over  a  bed  of  moss  peat. 

Where  the  soil  consists  very  largely  of  decaying  peat  to  a  depth 
of  30  inches  or  more,  it  is  called  deep  peat. 

As  shown  in  Table  15,  deep  peat  contains  in  one  million  pounds 
of  surface  soil  about  35,000  pounds  of  nitrogen,  2000  pounds  of 
phosphorus,  and  2900  pounds  of  potassium.  This  shows  in  the 


ILLINOIS   FIELD    EXPERIMENTS 


471 


surface  6f  inches  of  an  acre  about  five  times  as  much  nitrogen  as 
the  early  Wisconsin  black  clay  loam  prairie.  In  phosphorus  con- 
tent these  two  soil  types  are  about  equal,  but  the  peat  contains 
less  than  one  tenth  as  much  potassium  as  the  black  clay  loam. 
Thus,  the  total  supply  of  potassium  in  the  peat  to  a  depth  of  6f 
inches  (2930  pounds)  would  be  equivalent  to  the  full  potassium  re- 
quirement (75  pounds)  of  a  hundred-bushel  crop  of  corn  for  only 
39  years,  or  if  the  equivalent  of  only  one  fourth  of  i  per  cent 
of  this  is  annually  available  in  accordance  with  the  rough  estimate 
previously  suggested,  about  7  pounds  of  potassium  would  be  liber- 
ated annually,  or  sufficient  for  about  10  bushels  of  corn  per  acre. 

In  Table  91  are  given  all  results  obtained  from  the  Manito 
(Mason  County,  Illinois)  experiment  field  on  deep  peat,  which  was 
begun  in  1902  and  discontinued  after  1905.  The  plots  in  this  field 
were  one  acre  l  each  in  size,  being  2  rods  wide  and  80  rods  long, 
and  untreated  half-rod  division  strips  were  left  between  the  plots, 
which,  however,  were  cropped  the  same  as  the  plots. 

TABLE  91.   CORN  YIELDS  PER  ACRE  IN  ILLINOIS  SOIL  EXPERIMENTS  :  MANITO' 
FIELD:   TYPICAL  DEEP  PEAT  SOIL 


PLOT 

No. 

SOIL  TREATMENT  FOR 
1902  (Per  Acre) 

CORN, 

IQO2 

(Bu.) 

CORN, 
1003 
(Bu.) 

SOIL  TREATMENT  FOR 
1904  (Per  Acre) 

CORN, 

IQ04 

(Bu.) 

CORN, 
1005 
(Bu.) 

FOUR 
CROPS 
(Bu.) 

I 
2 

None     

10.9 

10.4 

8.1 

10.4 

None     

17.0 
12.  0 

I2.O 
10.  1 

48.0 
42.9 

None     

Limestone,  4000  Ib. 

3 
4 

5 

Kainit,  600  Ib.     .     . 

Kainit,  600  Ib.  ;  acid- 
ulated   bone,    350 
Ib       

3°-4 

30-3 
31.2 

32.4 

33-3 
33-9 

Limestone,  4000  Ib.  ; 
kainit,  1200  Ib. 
Kainit,     1200     Ib.  ; 
steamed  bone,  395 
Ib  

49.6 

53-5 
48-5 

47-3 

47-6 
52-7 

159-7 

164.7 
166.3 

Potassium     chlorid, 
200  Ib  

Potassium     chlorid, 
400  Ib  

6 

Sodium  chlorid,  700 
Ib  

II.  I 

i3-i 

None     

24.0 

22.1 

70.3 

7 

8 
9 

Sodium  chlorid,  700 
Ib  

!3-3 
36.8 
26.4 

14-5 
37-7 
25.1 

Kainit,  1200  Ib.  .     . 

Kainit,  600  Ib.    .     . 
Kainit,  300  Ib.    . 

44-5 

44.0 
4i-5 

47-3 

46.0 
329 

164.5 
125.9 

Kainit,  600  Ib.     .     . 
Kainit,  300  Ib.     . 

10 

None     

I4-92 

14.9 

None     

26.0 

13.6 

69.4 

1  In  1904  the  yields  were  taken  from  quarter-acre  plots  because  of  severe  insect 
injury  on  the  other  part  of  the  field. 

*  Estimated  from  1903;  no  yield  was  taken  in  1902  because  of  misunderstanding. 


472     INVESTIGATION    BY    CULTURE   EXPERIMENTS 

The  results  of  four  years'  tests  as  given  in  Table  91  are  in  com- 
plete harmony  with  the  information  furnished  by  the  chemical 
composition  of  peat  soil  as  compared  with  that  of  ordinary  normal 
soils.  Where  potassium  was  applied,  the  yield  was  from  three  to 
four  times  as  large  as  where  nothing  was  applied.  Where  approxi- 
mately equal  money  values  of  kainit  and  potassium  chlorid  were 
applied,  slightly  greater  yields  were  obtained  with  the  potassium 
chlorid,  which,  however,  supplied  about  one  third  more  potassium 
than  the  kainit'.  On  the  other  hand,  either  material  furnished  more 
potassium  than  was  required  by  the  crops  produced. 

The  use  of  700  pounds  of  sodium  chlorid  (common  salt)  produced 
no  appreciable  increase  over  the  best  untreated  plots,  indicating 
that  where  potassium  is  itself  actually  deficient,  salts  of  other  ele- 
ments cannot  take  its  place. 

Applications  of  two  tons  per  acre  of  ground  limestone  produced 
no  increase  in  the  corn  crops,  neither  when  applied  alone  nor  in 
combination  with  kainit,  neither  the  first  year  nor  the  second. 

Reducing  the  application  of  kainit  from  600  pounds  to  300 
pounds,  for  each  two-year  period,  reduced  the  yield  of  corn  from 
164.5  to  125.9  bushels.  The  two  applications  of  300  pounds  of 
kainit  furnished  60  pounds  of  potassium  for  the  four  years,  or 
sufficient  for  84  bushels  of  corn  (grain  and  stalks).  The  difference 
between  this  and  the  125.9  bushels  obtained  is  42  bushels,  about 
what  was  obtained  from  the  poorest  untreated  plot. 

The  underdrainage  provided  for  this  experiment  field  was  not 
sufficient  for  the  best  results,  probably  because  of  insufficient 
nitrification.  In  other  experiments  on  peaty  soil  with  imperfect 
drainage,  the  addition  of  $15  worth  of  nitrogen  with  potassium 
produced  about  15  bushels  more  corn  than  where  potassium  alone 
was  used. 

Peaty  alkali  soils.  Aside  from  deep  peat,  there  are  many 
other  types  of  peaty  soil,  as  will  be  seen  from  the  classification  of 
Illinois  soil  types  given  in  a  previous  chapter.  Thus  we  find  shallow 
peat  and  medium  peat,  underlain  with  clay,  sand,  rock,  etc.,  and 
also  sandy  peat  and  peaty  loam;  and  in  some  instances  peaty 
soils  also  contain  alkali,  consisting  chiefly  of  harmless  calcium  car- 
bonate with  smaller  amounts  of  injurious  magnesium  carbonate. 

In  some  cases  these  peaty  soils  actually  contain  a  good  percentage 


ILLINOIS   FIELD    EXPERIMENTS 


473 


of  total  potassium,  more  commonly  in  the  subsurface  or  subsoil, 
but  sometimes  in  the  surface  soil,  also;  and  yet  the  untreated  soil 
is  unproductive,  while  the  addition  of  potassium  salts  produces 
large  and  very  profitable  increases  in  the  yield  of  corn,  oats,  etc. 

In  pot-culture  experiments  the  author  has  even  been  able  by  the 
addition  of  potassium  sulfate  to  correct  to  a  considerable  extent 
the  injurious  property  of  magnesium  carbonate  that  has  been 
purposely  applied  to  ordinary  brown  silt  loam  prairie  soil  which  is 
known  to  contain  abundance  of  available  potassium.  These  facts 
are  mentioned  here  because  he  recommends,  in  humid  sections, 
trial  applications  of  potassium  salt  to  all  classes  of  peaty  and  alkali 
soils  that  are  unproductive  after  being  well  drained,  whenever 
the  supply  of  farm  manure  is  insufficient.  It  should  be  understood 
that  plenty  of  farm  manure,  preferably  quick-acting,  or  readily 
decomposable,  manure,  such  as  horse  manure,  will  supply  potas- 
sium and  thus  accomplish  everything  that  potassium  salts  can 
accomplish,  and  on  some  swamp  soils  manure  produces  good  re- 
sults where  potassium  is  without  effect. 

In  pot-culture  experiments  soils  containing  injurious  amounts 
of  magnesium  carbonate  have  been  treated  with  calcium  sulfate 
(land-plaster)  which  brings  about  a  double  decomposition,  or  inter- 
change, forming  the  harmless  insoluble  calcium  carbonate  (lime- 
stone) and  the  very  soluble  magnesium  sulfate,  which  is  subse- 
quently leached  out,  leaving  the  soil  productive.  (Seepage  171.) 

The  new  Manito  experiment  field  is  on  alkali  soil  consisting  of 
peaty,  clayey  sand  with  some  gravel,  and  containing  sufficient 
total  potassium  for  normal  crop  yields.  In  Table  92  are  recorded 
the  treatment  applied  and  results  obtained  in  1907. 

TABLE  92.     CORN  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:  NEW  MANITO 
FIELD:    PEATY  ALKALI  SOIL 


PLOT  No. 

TREATMENT  APPLIED  FOR  1907 

CORN 
(Bu.  per  Acre) 

2OI 

202  W. 
2O2  E. 
203 
204 

205 

None     .... 

8.8 

43-5 
64.9 

73-o 
•4.9 

5-4 

Manure,  6  tons  . 

Manure,  12  tons 
Potassium  sulfate, 
Calcium  sulfate,  2 
None     .... 

400  pounds  

to  16  tons     

474    INVESTIGATION   BY   CULTURE    EXPERIMENTS 

Plot  204  is  divided  into  four  equal  parts  and  the  calcium  sulfate 
applied  at  the  rate  of  2  tons,  4  tons,  8  tons,  and  16  tons  per  acre, 
at  a  cost  of  $6  per  ton.  It  produced  no  benefit  in  1907.  Whether 
it  will  assist  in  the  removal  of  the  magnesium  carbonate  by  double 
decomposition  and  leaching  and  thus  improve  the  soil  in  time, 
time  alone  will  tell.  (The  1908-1911  crops  show  no  benefit.) 

The  400  pounds  of  potassium  sulfate  are  applied  for  a  three- 
year  rotation  at  an  initial  cost  of  $10.  The  increase  of  66  bush- 
els of  corn  produced  the  first  year,  at  35  cents  a  bushel,  amounts 
to  more  than  twice  the  total  cost  of  the  potassium.  The  manure 
also  gave  very  excellent  results. 

In  Table  93  are  given  all  results  obtained  during  six  years' 
experiments  on  part  of  theMomence  soil  experiment  field,  located 
in  Kankakee  County,  Illinois,  near  the  Indiana  line,  on  peaty  swamp 
land  which  contains  much  decaying  peat  and  coarse  sand  in  the 
surface  and  subsurface,  with  a  clayey  sand  subsoil  resting  on 
impure  limestone,  while  the  surface,  subsurface,  and  subsoil 
contain  more  than  half  of  the  normal  amounts  of  total  potassium 
(19,000,  47,000,  and  73,000  pounds,  respectively,  per  acre).  The 
soil  contains  but  little  alkali. 

After  1902  (when  the  corn  was  damaged  by  water)  the  land  was 
tile-drained  sufficiently  well  for  ordinary  years,  but  in  the  ex- 
tremely wet  season  of  1907  the  corn  was  planted  very  late,  and  with 
the  continued  wet  weather  resulted  in  almost  a  complete  failure. 

Potassium  was  not  applied  to  plot  102  for  1902  and  1903,  and 
was  not  applied  to  plot  no  for  1904.  The  untreated  check  plot 
101  is  naturally  somewhat  more  productive  than  the  other  plots. 

These  results  from  the  newManito  field  and  from  theMomence 
field,  on  abnormal  swamp  lands,  emphasize  the  fact  that,  although 
some  principles  are  well  established  and  can  be  applied  with  normal 
results  on  normal  soils  and  on  some  abnormal  soils  (as  the  deep  peat 
and  sand  ridge  soils),  there  are  complex  problems  still  unsolved 
relating  to  soils  and  soil  fertility. 

These  problems  may  be  chemical,  physical,  or  biological,  and 
their  solution  may  require  the  application  of  science  yet  unknown. 
Thus,  some  essential  element  of  plant  food  may  be  present  in 
abundance  but  held  in  unavailable  form  by  physical  combination, 
as  in  grains  of  sand :  or  there  may  exist  some  still  undiscovered 


ILLINOIS   FIELD    EXPERIMENTS 


475 


TABLE  93.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:  MOMENCE  FIELD 


PLOT 
No. 

PEATY  SWAMP  LAND:  SOIL  TREAT- 
MENT APPLIED 

CORN  (Bushels  per  Acre) 

6  CROPS 

1902 

1903 

1904 

1905 

1906 

1907 

Bu. 

Value 

101 
IO2 

None      

6.6 

5-5 

14.9 

7-i 

4.8 

20.1 

6.8 
3S-9 

6.8 

<?2.6 

•3 
14.9 

40-5 

$14.18 

Lime  (and  potassium  after  2 
years)  

I03 
104 

105 

Lime,  nitrogen     
Lime,  phosphorus     .... 
Lime,  potassium  

o.o 

i-3 

23-7 

3-6 
4.6 
72.2 

J-3 

•4 
34-6 

4.1 
1.8 
41.4 

5-3 
1.9 

50.0 

•4 

.2 

16.2 

14.7 
IO.2 

238.1 

$5-15 

3-57 

83-34 

106 
107 
108 

Lime,  nitrogen,  phosphorus  . 
Lime,  nitrogen,  potassium  .     . 
Lime,  phosphorus,  potassium  . 

0.0 

19.7 

32.0 

3-9 
71.1 

73-i 

.6 

33-5 
42.0 

1.6 

38-5 
36.3 

4-5 
53-i 
59-4 

•4 
16.5 
19.9 

II.O 
232.4 
262.7 

$  3-85 

81.34 
91-95 

109 
no 

Lime,  nitrogen,  phosphorus,  po- 
tassium      

25.2 
24.1 

66.8 
70.4 

39-2 
19.0 

42.9 
24.8 

65.6 

51-3 

25.1 

23-4 

264.8 

$92.68 

Nitrogen,  phosphorus,  potassium 

chemical  substances  injurious  to  agricultural  plants  or  to  necessary 
bacterial  life,  which  may  be  corrected  or  destroyed  by  potassium 
salts  or  other  materials;  and  the  recent  very  extensive  investi- 
gations by  the  United  States  Bureau  of  Soils  indicate  that  condi- 
tions may  be  brought  about,  artificially  at  least,  in  which  organic 
toxic  substances  develop  that  are  injurious  to  plant  growth. 

TABLE  88,  continued.     LATE  CROP  YIELDS:   BLOOMINGTON  FIELD 


PLOT 

No. 

SOIL  TREATMENT  APPLIED 

OATS, 
1909 

CLOVER, 
1910  * 

WHEAT, 
1911 

VALUE  OF 
10  CROPS 

VALUE  OP 
INCREASE 

IOI 

102 

None     
Lime      

46.4 

53-6 

1.56 

1.09 

22.5 
22.5 

$147-9° 
I48./5 

$      .85 

103 
IO4 
IOS 

Lime  and  crop  residues    . 
Lime  and  phosphorus  .     . 
Lime  and  potassium    .     . 

49-4 
63-8 

45-3 

(.83) 
4.21 
1.26 

25.6 

57-6 
21.7 

8151.30 
229.37 

149-43 

$  3-40 
81.47 
i-53 

106 
107 

108 

Lime,  residues,  phosphorus 
Lime,  residues,  potassium 
Lime,  phosphorus,  potassium 

72.5 
Si-i 
59-5 

(I.67) 
(-33) 
3-27 

60.2 

27-3 
54-o 

§221.30 
149.96 
220-  2O 

$73-40 
2.06 
81.30 

109 
no 

Lime,  crop  residues,  phos- 
phorus, potassium     .     . 
Crop  residues,  phosphorus, 
potassium   

64.2 
55-3 

(.42) 
(.60) 

60.4 
61.0 

§225.57 
209.26 

S77.67 
61.36 

1  Figures  in  parentheses  for  bushels  of  seed ;   the  others  for  tons  of  hay. 


CHAPTER  XXIII 

FIELD    EXPERIMENTS    IN    THE    SOUTH,    INCLUDING    SOUTHERN 

ILLINOIS 

THE  gray  silt  loam  on  tight  clay  is  one  of  the  common  types  of 
prairie  land  in  the  Kansan  and  lower  Illinoisan  glaciations.  This 
or  very  similar  prairie  soil  is  found  in  many  places,  as  in  south- 
ern Illinois,  northern  Missouri,  southern  Iowa,  and  southeastern 
Kansas.  In  Illinois  this  soil  type  is  found  chiefly  between  the 
Kaskaskia  and  Wabash  rivers  in  an  area  bounded  on  the  south  by 
the  Ozark  Hills  and  on  the  north  by  the  terminal  moraine  of  the 
Wisconsin  glaciation,  which  passes  through  Shelby,  southern  Coles, 
and  Edgar  counties. 

This  type  of  soil  is  well  known  and  everywhere  recognized  by  the 
farmers  themselves  as  "  hardpan  land."  It  consists  of  a  friable  gray 
silt  loam  which  commonly  varies  in  depth  from  6  to  1 2  inches,  and 
below  which  is  a  light  gray  or  nearly  white  layer,  or  stratum,  of 
slightly  loamy  silt  varying  from  less  than  one  inch  to  more  than  10 
inches  in  thickness,  and  commonly  referred  to  as  "  the  gray  layer." 
At  a  depth  of  16  to  20  inches  the  soil  is  underlain  by  a  tight  clay 
subsoil,  frequently  termed  "  hardpan."  It  should  be  understood, 
however,  that  this  subsoil  is  not  true  hardpan,  which  consists  of 
sand  or  gravel  cemented  together  with  clay  to  form  a  substance 
which  is  practically  impervious  to  water. 

The  subsoil  of  this  gray  silt  loam  prairie  is  a  tight  clay,  inclined 
to  be  gummy.  Water  passes  through  it,  although  quite  slowly, 
and  when  wet  it  can  be  spaded  without  special  difficulty,  but  when 
dry  it  becomes  stiff  and  hard.  Closely  related  to  this  prairie  soil 
are  level  upland  timbered  soils  underlain  with  tight  clay,  found 
in  the  southern  part  of  Indiana,  Illinois,  and  Iowa,  and  also  in 
northern  Missouri  and  western  Kentucky. 

Where  this  soil  is  enriched  by  proper  treatment,  excellent  crops 
are  grown  in  seasons  of  normal  rainfall,  but  they  are  likely  to  suffer 
in  times  of  drouth  more  than  would  be  the  case  with  a  better  sub- 

476 


FIELD   EXPERIMENTS   IN   THE   SOUTH  477 

soil.  As  a  rule,  the  rainfall  in  southern  Illinois  is  abundant  and  well 
distributed  during  the  growing  season,  and  where  the  top  soil  is 
kept  fertile,  severe  injury  from  drouth  is  not  common. 

From  Table  15  it  will  be  seen  that  the  average  surface  soil  of 
this  type  contains  per  acre  2880  pounds  of  nitrogen,  840  pounds 
of  phosphorus,  and  24,940  pounds  of  potassium,  and  it  requires 
an  application  of  2  to  5  tons  of  ground  limestone.  Compared  with 
the  requirements  for  a  practical  crop  rotation,  this  soil  is  very  poor 
in  phosphorus  and  very  deficient  in  lime.  Compared  with  the  com- 
position of  fertile  soils,  it  is  also  deficient  in  humus  as  indicated  by 
the  total  nitrogen. 

If  by  the  best  systems  of  crop  rotations,  with  proper  use  of  green 
manures,  we  can  liberate,  in  favorable  seasons,  the  equivalent  of 
i  per  cent  of  the  phosphorus  contained  in  the  surface  soil,  it  would 
amount  to  about  8  pounds  per  acre  for  the  first  year  for  the  type 
of  soil  under  consideration.  This  would  be  sufficient  for  a  25- 
bushel  crop  of  wheat.  If  with  less  perfect  systems  only  half  of  i 
per  cent  is  liberated,  it  would  amount  to  4  pounds,  or  enough  for  a 
i2-bushel  crop  of  wheat,  which  is  about  the  average  yield  for  this 
soil. 

On  the  Illinois  soil  experiment  field  near  Odin,  Marion  County, 
on  this  ordinary  prairie  land  of  the  lower  Illinoisan  glaciation, 
wheat  is  grown  in  a  four-year  crop  rotation  with  clover,  corn,  and 
cowpeas.  By  having  four  different  series  of  plots,  every  crop  may 
be  grown  every  year. 

As  an  average  of  four  years  (1904,  1905,  1906,  and  1907),  wheat 
grown  in  this  rotation  produced  1 1^  bushels  per  acre  with  no  special 
soil  treatment,  all  crops  having  been  removed. 

Where  one  cowpea  crop  and  some  catch  crops  (as  cowpeas  seeded 
in  the  corn)  had  been  plowed  under  during  the  rotation,  the  aver- 
age yield  of  wheat  was  increased  to  14  bushels. 

Where  lime  or  ground  limestone  had  been  applied  and  the  cow- 
peas  also  plowed  under,  the  average  yield  of  wheat  was  i8£  bushels 
per  acre.  On  this  set  of  plots  better  cowpea  crops  and  catch  crops 
were  produced  and  turned  under  as  green  manure,  because  the  soil 
acidity  had  been  corrected  by  the  lime,  applied  for  the  special 
benefit  of  the  legume  crops. 

Where  phosphorus  was  applied  in  addition  to  the  use  of  lime  and 


green  manure,  the  average  yield  of  wheat  during  the  four  years  was 
27  bushels;  and  where  potassium  also  was  included,  the  average 
yield  was  29!  bushels  of  wheat  per  acre. 

These  results  are  quite  in  harmony  with  what  might  be  expected 
from  the  chemical  composition  of  the  soil.  If,  however,  we  con- 
sider the  corn  crops  in  the  same  rotation,  we  have  a  somewhat 
different  set  of  results. 

The  average  yield  of  corn  for  the  four  years  on  the  untreated 
rotated  land  was  38  bushels  per  acre;  with  legume  treatment 
(cowpeas  turned  under),  41  bushels;  with  legume  and  lime  treat- 
ment, 45  bushels;  with  legume,  lime,  and  phosphorus,  46  bushels; 
and  with  legume-lime  phosphorus-potassium  treatment  the  average 
yield  of  corn  for  four  years  was  61  bushels  per  acre. 

For  more  convenient  comparison,  these  results  are  shown  in 
Table  94. 

TABLE  94.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:    ODIN  FIELD 


GRAY  SILT  LOAM  PRAIRIE:  LOWER  ILLINOISAN  GLACIATION 

AVERAGE  OF  EIGHT  TESTS  IN 
FOUR  YE  ADS;  Two  TESTS  EACH 
YEAR  FOR  EACH  CROP 
(Bushels  per  Acre) 

Soil  Treatment  Applied 

Wheat 

Corn 

None  (except  rotation)      

II.  6 
I3.8 
I8.S 
27.1 
29-5 

38.3 

40.8 

45-3 
46.2 

6i-3 

Legume  (cowpeas  turned  under)     

Legume,  lime       

Legume,  lime,  phosphorus     ....          .     . 

Legume,  lime,  phosphorus,  potassium     .     . 

These  results  are  four-year  averages.  They  were  made  in  dupli- 
cate each  year.  They  are  representative  and  trustworthy.  They 
have  also  been  confirmed  by  results  from  other  experiment  fields 
on  the  same  type  of  soil. 

The  effects  upon  corn  of  the  green  manure  alone  and  with  lime 
are  about  the  same  as  upon  wheat,  but  the  effects  produced  by 
phosphorus  and  potassium  are  very  different  with  the  two  crops, 
phosphorus  producing  the  largest  increase  in  wheat,  while  potas- 
sium is  much  more  effective  with  corn,  although  potassium  without 
phosphorus  (in  other  experiments)  produces  less  increase  in  corn 
than  when  applied  in  addition  to  phosphorus. 


FIELD   EXPERIMENTS   IN   THE   SOUTH  479 

A  study  of  Table  23  will  show  that  a  6i-bushel  crop  of  corn  re- 
quires more  potassium  than  a  3o-bushel  crop  of  wheat,  which  fact 
may  account  in  part  for  the  greater  effect  of  potassium  on  corn, 
although  about  the  same  relation  holds  for  phosphorus.  A  more 
important  difference  probably  exists  in  the  relative  feeding  powers 
of  the  two  crops,  influenced  (i)  by  the' difference  in  root  system, 
including  the  different  depths  of  feeding,  (2)  by  the  difference  in 
seasonal  conditions  and  consequent  difference  in  decay  of  humus, 
in  decomposition  of  other  soil  materials,  and  in  activity  of  soil 
organisms  during  the  principal  period  of  growth,  (3)  by  the  sol- 
vent action  of  the  carbon  dioxid  excreted  by  the  bacteria  and  from 
the  plant  roots,  and  (4)  possibly  by  different  requirements  as  to 
the  forms  or  combinations  in  which  the  plant-food  elements  can 
be  absorbed  and  assimilated  or  utilized  by  corn  and  wheat. 

The  Rothamsted  data  contribute  much  toward  the  solution  of 
this  practical  problem,  but  the  very  important  question  recurs, 
whether  more  or  less  of  the  effect  attributed  to  potassium  may  not 
be  due  to  the  stimulating  action  of  the  soluble  potassium  salt  in 
liberating  other  substances  from  the  soil  instead  of  serving  directly 
as  plant  food;  and,  if  so,  would  it  be  advisable  and  more  profitable 
to  substitute  some  other  less  expensive  material,  such  as  kainit, 
for  the  concentrated  potassium  sulfate  used  in  these  experiments  ? 

It  can  also  be  stated  that  as  an  average  of  56  tests  (including 
the  use  of  twenty-five  different  varieties  of  corn)  conducted  in 
1907  and  1908  on  the  Illinois  experiment  field  near  Fairfield  in 
Wayne  County,  on  the  same  type  of  soil,  an  application  of  200 
pounds  per  acre  of  potassium  sulfate,  containing  85  pounds  of  the 
element  potassium  and  costing  $5,  increased  the  yield  of  corn  by 
5.4  bushels  per  acre;  while  600  pounds  of  kainit  containing  only 
60  pounds  of  potassium  and  costing  $4,  gave  9.9  bushels'  increase. 
These  applications  are  made  but  once  for  a  four-year  rotation. 
The  kainit  with  25  pounds  less  potassium  produced  4.5  bushels 
more  corn  than  the  sulfate.  At  40  cents  a  bushel  for  corn,  the  kainit 
has  paid  for  itself.  Kainit  contains  about  25  per  cent  of  potassium 
sulfate  together  with  some  16  per  cent  of  magnesium  sulfate,  12 
per  cent  of  magnesium  chlorid,  and  33  per  cent  of  sodium  chlorid, 
all  of  which  are  soluble  salts;  and  the  results  plainly  indicate  that 
the  effects  produced  are  due  not  solely  to  the  element  potassium, 


480     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

but  in  part  at  least,  and  probably  in  large  part,  to  the  stimulating 
action  of  the  soluble  salt. 

The  soluble  salts  were  applied  in  addition  to  phosphorus  and  the 
yields  compared  with  the  results  obtained  where  the  same  amounts 
of  phosphorus  were  applied  without  the  soluble  salts  mentioned. 
Limestone  was  also  provided  in  all  cases.  The  soil  is  not  well 
supplied  with  decaying  organic  matter,  the  action  of  which  will 
largely,  or,  if  provided  in  abundance,  entirely  take  the  place  of  the 
action  of  the  soluble  salts  as  such.  Additional  experiments  on  the 
Fairfield  field  include  an  equally  complete  test  with  kainit  and 
potassium  sulfate  on  land  to  which  8  tons  per  acre  of  farm  manure 
had  been  applied.  As  an  average  of  56  tests  with  each  material, 
200  pounds  of  potassium  sulfate  increased  the  yield  of  corn  by  1.6 
bushels,  while  the  600  pounds  of  kainit  gave  1.4  bushels'  increase, 
as  compared  with  5. 4  bushels'  and  9.9  bushels'  increase,  respectively, 
where  these  soluble  salts  were  applied  in  the  absence  of  manure, 
all  other  conditions  being  the  same. 

Thus,  where  farm  manure  is  supplied,  the  soluble  salts  produced 
but  little  effect  and  are  not  used  with  profit.  On  the  other  hand, 
phosphorus  usually  produces  its  greatest  effect  when  used  in  con- 
nection with  organic  matter. 

In  Table  95  are  given  the  results  obtained  during  seven  years  on 
the  Du  Bois  experiment  field,  in  Washington  County,  Illinois, 
on  the  same  soil  type  (gray  silt  loam  on  tight  clay).  In  this  field 
there  are  two  independent  series  of  ten  plots  each,  and  the  crop 
yields  reported  in  the  table  are  in  all  cases  the  average  from  two 
plots  with  like  treatment. 

For  convenient  comparison  it  may  be  stated  that  at  conservative 
prices  the  value  of  the  seven  crops  on  the  untreated  land  is  $34.30, 
while  $99.11  represents  the  corresponding  value  from  an  acre  treated 
with  lime,  bone  meal,  and  potassium  sulphate,  costing  $46.25. 

The  yellow  silt  loam  is  found  in  all  glaciations,  and  much  more 
abundantly  (relatively)  in  the  unglaciated  areas  in  the  South 
Central  states.  Like  most  of  the  soils  of  the  Central  states,  it 
consists  of  a  loessial  deposit.  It  occupies  much  of  the  sloping  lands 
or  hillsides,  not  only  in  the  original  hilly  sections  (as  in  the  un- 
glaciated, or  driftless,  areas  from  southern  Illinois  to  northern 
Mississippi) ,  but  also  in  the  broken  land  regions  along  most  of  the 


FIELD    EXPERIMENTS    IN   THE    SOUTH 


481 


TABLE  95.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:  Du  Bois  FIELD 


GRAY  SILT  LOAM  PRAIRIE:  LOWER  ILLINOISAN 
GLACIATION 

AVERAGE  OF  Two  SERIES  EACH  YEAR 
(Bushels  or  Tons  per  Acre) 

Soil  Treatment  Applied 

Corn 
1902 

Oats 
1903 

Wheat 
1904 

Clover 
1005 

Corn 
1906 

Oats 
1007 

Wheat 
1908 

None     

4-9 
5-o 

13-3 
I6.7 

4.8 
9.0 

1.27 
1.67 

3J-4 
34-4 

16.0 

26.3 

2.6 
9-5 

Lime     

Lime,  nitrogen    

4-3 

10.0 

8-3 

19.4 
26.7 
27.4 

IO.I 

26.7 

15-5 

1.79 

2-35 
2.19 

34-9 
34-2 
48.2 

34-i 
37-9 
41.8 

n-5 
18.5 
i5-5 

Lime,  phosphorus  

Lime,  potassium      

Lime,  nitrogen,  phosphorus 
Lime,  nitrogen,  potassium    .... 
Lime,  phosphorus,  potassium    .     .     . 

8.7 
7.2 
13-3 

29.4 

25-5 
27.8 

32.0 

21.8 

29.9 

2-37 
2-43 
2.91 

3x-4 
46.0 

52.i 

46-3 
4i-5 

47.2 

19.7 

17-5 
21.9 

20.5 

II.  0 

Lime,  nitrogen,  phosphorus,  potassium 
Nitrogen,  phosphorus,  potassium  .     . 

10.4 

3-4 

3°-5 
29.4 

3r-9 

27.8 

2.86 
2.69 

49.0 
45-3 

44.4 
36.1 

interior  streams  in  glaciated  areas.  Under  ordinary  methods  of 
cultivation  these  lands  are  subject  to  serious  loss  from  surface 
washing,  and  even  when  not  under  cultivation  there  is  and  has 
been  more  or  less  rapid  erosion  taking  place.  Where  this  soil  has 
been  under  ordinary  cultivation  for  several  years,  it  is  almost 
invariably  poor  in  humus  and  nitrogen,  and  the  dominant  problem 
is  to  maintain  or  increase  the  organic  matter  in  the  soil,  which  will 
also  increase  the  nitrogen. 

Of  course  the  organic  matter  must  in  large  part  at  least  be  grown 
upon  the  land,  and  legume  crops  are  most  suitable  for  this  purpose 
because  their  growth  is  not  limited  by  the  small  nitrogen  content 
of  the  soil,  and  they  also  furnish  green  manures  or  animal  manures 
rich  in  nitrogen. 

While  these  soils  are  not  rich  in  phosphorus,  that  element  is  not 
the  chief  limit  to  the  yield  of  crops  because  the  nitrogen  limit  is  so 
much  lower  as  measured  by  crop  requirements  and  by  culture 
experiments.  Furthermore,  by  surface  washing,  the  nitrogen, 
which  is  contained  only  in  the  humus,  is  rapidly  depleted,  while 
the  phosphorus  is  constantly  renewed  because  of  the  supplies  in 
the  underlying  materials.  It  is  certain  that  for  the  highest  crop 
yields  phosphorus  must  be  applied,  and  very  probably  it  can  ulti- 
mately be  applied  with  profit  in  the  best  systems  of  soil  improve- 


482     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

ment  and  preservation,  but,  as  stated  above,  the  first  requisite 
is  an  increase  in  humus  and  nitrogen. 

There  is,  however,  a  serious  difficulty  to  the  growing  of  legume 
crops,  especially  for  clover  and  alfalfa.  This  type  of  soil,  where  it 
has  been  long  under  cultivation,  is  markedly  sour  or  acid.  This  ap- 
plies to  the  Kansan  glaciation  in  Missouri  and  to  the  lower  Illi- 
noisan  glaciation,  and  especially  to  the  unglaciated  yellow  silt  loam 
in  the  southern  parts  of  Illinois  and  Indiana,  and  in  the  loess- 
covered  areas  of  Missouri,  Kentucky,  Tennessee,  and  Mississippi. 

In  the  northern  glaciations  this  type  of  soil  is  less  acid  than  in 
the  Kansan  and  lower  Illinoisan,  but  it  is  usually  more  or  less  acid 
in  the  middle  and  upper  Illinoisan,  in  the  pre-Iowan  and  lowan, 
and  even  in  the  early  Wisconsin  glaciation,  —  and  not  only  in  the 
Central  states,  but  also  in  New  York  and  other  Eastern  states. 

In  the  unglaciated  areas  and  in  the  lower  Illinoisan  and  Kansan 
glaciations  initial  applications  of  at  least  two  tons  per  acre  of  ground 
limestone  are  recommended  for  the  yellow  silt  loam;  and  for  the 
other  glaciations  two  tons  or  more  may  well  be  applied  where 
acidity  is  shown  in  the  surface  and  subsoil  and  where  difficulty  is 
encountered  in  the  growing  of  red  clover  or  alfalfa. 

One  of  the  very  best  crops,  and  probably  the  most  satisfactory 
and  profitable  crop,  to  be  grown  on  these  yellow  silt  loam  soils  is 
alfalfa.  Its  power  to  secure  nitrogen  from  the  air,  to  root  deeply, 
and  to  live  for  many  years  are  all  very  great  advantages  for  this 
soil.  Furthermore,  experiments  have  shown  that  where  the  land 
is  properly  treated  with  heavy  applications  of  lime  or  ground 
limestone  (five  tons  per  acre)  and  thoroughly  inoculated  with  the 
alfalfa  bacteria  and  the  alfalfa  seeded  on  well-prepared  and  well- 
manured  land  at  the  proper  time  and  given  proper  care,  it  grows 
luxuriantly  and  yields  large  and  profitable  crops  on  this  soil,  as 
in  Illinois,  Ohio,  and  New  York.  On  the  other  hand,  to  sow  20  to 
25  pounds  of  good  alfalfa  seed  on  this  soil  without  special  and 
proper  treatment  is  much  like  throwing  away  about  $4  an  acre. 

Of  course,  if  alfalfa  is  grown  on  this  land,  it  should  be  fed  on  the 
farm,  in  part  at  least,  and  the  manure  returned  to  the  soil,  not 
only  to  help  the  alfalfa  but  also  for  other  crops  to  be  grown,  such 
as  corn  and  potatoes,  which  are  a  very  profitable  crop  for  this  soil 
when  properly  enriched. 


FIELD    EXPERIMENTS   IN   THE   SOUTH 


483 


Table  96  gives  the  yields  of  corn,  wheat,  and  clover  obtained 
in  1907  on  the  Vienna  soil  experiment  field  in  Johnson  County, 
Illinois,  located  on  the  less  rolling  phase  of  yellow  silt  loam  in  the 
unglaciated  area,  and  typical  of  more  extensive  areas  of  this  type 
in  other  Southern  states.  (It  should  be  remembered  that  geo- 
graphically and  agriculturally  one  third  of  Illinois  belongs  with  the 
South  Central  states.  A  straight  line  from  the  north  point  of 
Kentucky  to  the  northeast  corner  of  Missouri  divides  Illinois  into 
two  practically  equal  parts.) 

The  land  on  which  the  Vienna  field  is  located  has  been  cropped 
for  about  seventy-five  years.  It  had  never  had  any  soil  treatment, 
so  far  as  can  be  determined,  and  was  badly  run  down  when  the 
Experiment  Station  came  into  possession  of  it  in  1902. 

The  field  is  divided  into  three  series  of  five  fifth-acre  plots. 
A  three-year  rotation  of  corn,  cowpeas,  and  wheat  was  followed  for 
four  years,  then  changed  to  corn,  wheat,  and  clover,  but,  excepting 
the  1907  crop,  the  clover  has  failed.  Cowpeas  have  been  substi- 
tuted and  the  crop  harvested  or  plowed  under,  as  seemed  practical, 
according  to  the  yield  and  weather  conditions.  In  1902,  oats  were 
grown  in  the  place  of  wheat. 

The  soil  treatment  has  been  as  follows: 

Plot  i  of  each  series,  no  treatment  except  as  the  cowpea  stubble  or  the 
second  growth  of  clover  has  been  plowed  under  in  the  regular  course  of  the 
rotation. 

Plot  2,  legume  crops  and  catch  crops  plowed  under,  except  in  1905-1906-1907. 

Plot  3,  legumes  plowed  under  and  lime  applied. 

Plot  4,  legume,  lime,  and  phosphorus. 

Plot  5,  legume,  lime,  phosphorus,  and  potassium. 

TABLE  96.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:    VIENNA  FIELD 


YELLOW  SILT  LOAM  HILL  LAND:  UNGLACIATED 
AREA 

SERIES 

100, 

CORN, 
1907 

SERIES 
300, 
WHEAT, 
1907 

SERIES 
200, 
CLOVER, 
1907 

VALUE  OF 
THREE  CROPS 

Plot 

Soil  Treatment  Applied 

Bushels  or  Tons  per  Acre 

Total 

Increase 

I 
2 

3 
4 

5 

None      

I6.7 
I7.8 
3°-3 

37-1 
38.1 

4-3 
6.1 
13.0 
13.6 

15-6 

-65 
.81 
1.92 
2.56 

2.23 

$12.76 
I5-36 

3r-23 
37-87 

37-64 

$  2.60 

18.47 
25.11 

24.88 

Legume      

Legume,  lime       

Legume,  lime,  phosphorus 
Legume,  lime,  phosphorus,  potas- 
sium     

484     INVESTIGATION   BY   CULTURE    EXPERIMENTS 

The  primary  object  in  applying  lime  is  to  correct  soil  acidity. 
In  the  spring  of  1902  one  ton  per  acre  of  slacked  lime  was  applied; 
but,  a  method  having  been  worked  out  by  which  it  can  be  deter- 
mined by  chemical  analysis  how  much  lime  is  equivalent  to  the 
soil  acidity  to  any  depth,  it  was  found  that  the  soil  on  this  field 
was  acid  in  the  surface,  more  acid  in  the  subsurface,  and  still  more 
acid  in  the  subsoil ;  and  in  order  to  provide  ample  lime  to  correct 
this  acidity,  an  additional  application  of  eight  tons  per  acre  of 
ground  limestone  was  made  in  the  fall  of  1902.  From  all  informa- 
tion now  available,  it  is  believed  that  two  to  five  tons  per  acre  of 
ground  limestone  as  an  initial  application  will  give  very  satisfac- 
tory results.  Heavier  applications  may  give  more  profit  per  acre, 
but  less  profit  per  ton  of  limestone  used. 

Phosphorus  has  been  applied  at  the  rate  of  25  pounds,  and  po- 
tassium at  the  rate  of  42  pounds,  per  acre  per  annum,  the  present 
regular  practice  being  to  apply  once  in  three  years  600  pounds  of 
steamed  bone  meal,  containing  ii\  per  cent  phosphorus,  and  300 
pounds  of  potassium  sulfate,  containing  42  per  cent  of  potassium. 

Seven  crops  of  corn,  six  of  wheat,  one  crop  of  oats,  and  six  of 
cowpeas  and  one  of  clover  have  been  grown  on  the  field  since  the 
work  was  begun  in  1902.  The  yields  of  corn,  oats,  and  wheat  are 
given  in  Table  97. 

Counting  only  the  crops  removed,  the  limestone,  at  $1.50  per 
ton,  has  paid  for  itself  and  left  a  net  profit  of  34  per  cent;  and, 
assuming  1000  pounds'  loss  per  acre  per  annum,  more  than  half  of 
the  application  still  remains  in  the  soil.  Neither  phosphorus  nor 
potassium  has  been  used  with  profit,  but  it  is  interesting  to  note 
that  plot  5  has  produced  six  times  as  much  wheat  as  No.  i. 

Seasonal  conditions  have  very  markedly  influenced  the  yields  of 
crops.  Larger  use  of  crop  residues  to  increase  the  organic  matter 
of  the  soil  promises  further  improvement. 

Some  very  instructive  results  have  been  obtained  from  a  series  of 
pot-culture  experiments  which  have  been  in  progress  since  1902 
in  the  pot-culture  greenhouse  of  the  Illinois  Experiment  Station, 
and  in  which  this  yellow  silt  loam  of  the  unglaciated  hill  land  has 
been  used.  The  soil  was  collected  in  the  fall  of  1901,  and  represents 
the  old  worn  hill  soil  of  Pulaski  County,  Illinois,  only  a  few  miles 
from  Kentucky.  It  is  much  poorer  in  nitrogen  and  humus  than  the 


FIELD    EXPERIMENTS   IN   THE    SOUTH 


485 


TABLE  97.   CROP  YIELDS  IN  ILLINOIS  SOIL  EXPERIMENTS:    VIENNA  FIELD 
Corn,  Bushels  per  Acre 


1902 

1903 

1904 

1905 

1906 

1907 

1908 

TOTAL 

SOIL 

PLOT 

TREATMENT  APPLIED 

No. 

Series 

Series 

Series 

Series 

Series 

Series 

Series 

Seven 

IOO 

IOO 

300 

200 

300 

IOO 

200 

Years 

I 

None  

i1?.1; 

Q.-2 

30.  =; 

37.  "? 

41.2 

16.7 

IS.  2 

i8c  o 

2 

Legume   

17.  -2 

"vO 

^.^ 

42.  0 

40.  6 

17.8 

T>-6 

I  no  7 

3 

Legume,  lime    .     .     . 

14.9 

8-3 

49-1 

61.9 

48.9 

3°-3 

43-9 

257-3 

4 

Legume,   lime,    phos- 

phorus   

12.  "? 

4Q.4 

^7.2 

4O.O 

37.1 

42.0 

247  4 

5 

Legume,   lime,   phos- 

phorus, potassium   . 

19.9 

n.6 

44-7 

56.5 

40.9 

38.1 

50.6 

262.3 

Oats  or  Wheat,  Bushels  per  Acre 


Oats 

Wheat 

Wheat 

Wheat 

Wheat 

Wheat 

Wheat 

Wheat 

Series 

Series 

Series 

Series 

Series 

Series 

Series 

in 

200 

300 

200 

IOO 

200 

300 

IOO 

6  Years 

I 

None  

IQ.I 

.4 

6.7 

1.2 

r8 

A.T. 

none 

16  s 

2 

Legume  

V 

18.8 

•*t 

.6 

/ 

7.1 

O 

10.8 

o 

"v4 

*T  O 

6.1 

none 

L"'  j 
-2O.  O 

3 

Legume,  lime   .     .     . 

19.8 

•7 

/ 

IO.O 

18.2 

•j  ™ 

17.9 

13-0 

4-5 

JW.V. 

64-3 

4 

Legume,   lime,    phos- 

phorus   

20.  o 

8.0 

14.8 

2<.6 

ii.  3 

1:5.6 

8.? 

8l.6 

5 

Legume,   lime,   phos- 

~_;   v 

o 

*  o 

3 

phorus,  potassium  . 

3!-7 

II.  O 

17-5 

30.0 

15.0 

15-6 

9.8 

98.9 

average  of  the  type,  although  large  areas  are  to  be  found  as  badly 
worn  as  the  field  from  which  this  soil  was  collected.  This  field  has 
been  under  cultivation  for  about  seventy-five  years,  and  was  still 
cropped  when  the  soil  was  collected.  During  the  earlier  period  of 
its  cultivation  the  soil  frequently  produced  25  bushels  of  wheat  an 
acre,  but  during  the  later  years  about  5  bushels  has  been  the  aver- 
age crop  in  normal  seasons. 

Table  98  gives  the  results  from  six  years'  experiments  with  pot 
cultures  on  this  type  of  soil.  It  is  seen  that  practically  no  gain  has 
been  made  except  where  nitrogen  was  supplied,  either  directly  in 
commercial  form  or  indirectly  by  means  of  legume  treatment.  It 
should  be  borne  in  mind  that  no  legume  treatment  preceded  the 
1902  wheat  crop.  The  catch  crop  of  cowpeas,  which  was  planted 


after  the  1902  wheat  crop  and  turned  under  later  in  the  fall,  pro- 
duced a  marked  effect  upon  the  1903  wheat  crop.  This  effect  be- 
came more  marked  in  1904  and  1905,  when  every  pot  receiving 
legume  treatment  outyielded  the  pot  receiving  lime-nitrogen 
treatment. 

The  last  line  in  the  table  gives  the  yields  from  a  pot  of  virgin 
soil  collected  from  a  piece  of  unbroken  virgin  sod  land  adjoining 
the  cultivated  field  from  which  the  soil  in  all  the  other  pots  was 
taken.  It  is  seen  that  the  yields  frorn  this  pot  are  gradually  de- 
creasing, doubtless  due  to  the  exhaustion  of  the  more  active  or- 
ganic matter  in  the  soil. 

TABLE  98.   CROP  YIELDS  FROM  PULASKI  COUNTY  (ILLINOIS)  SOIL 
Pot-culture  Experiments 


YELLOW  SILT  LOAM  HILL  LAND  OF  THE 

UNGLACIATED  AREA 

1902 

1903 

1904 

1905 

1906 

1907 

WHEAT 

WHEAT 

WHEAT 

WHEAT 

WHEAT 

OATS 

(Grams) 

(Grams) 

(Grams) 

(Grams) 

(Grams) 

(Grams) 

Soil  Treatment  Applied 

None      

? 

c 

A 

A 

4 

6 

Legume,  lime       

A 

IO 

17 

26 

IO 

37 

Legume,  lime,  phosphorus     .     . 

3 

14 

19 

2O 

18 

27 

Legume,  lime,  phosphorus,  potas- 

sium   

3 

16 

20 

21 

iQ 

3° 

Lime,  nitrogen     

26 

17 

14 

If 

n 

28 

Lime,  phosphorus    

3 

6 

4 

6 

4 

8 

Lime,  potassium       ..... 

3 

3 

3 

5 

5 

10 

Lime,  nitrogen,  phosphorus  .     . 

34 

26 

20 

18 

18 

30 

Lime,  nitrogen,  potassium     .     . 

.33 

14 

21 

21 

16 

23 

Lime,  phosphorus,  potassium 

2 

3 

3 

5 

3 

7 

Lime,  nitrogen,  phosphorus,  po- 

34 

31 

34 

21 

20 

26 

tassium   

Virgin  soil  (no  treatment)      .     . 

24 

17 

15 

17 

13 

6 

The  results  from  the  pot  cultures  bear  out  very  conclusively  the 
results  obtained  from  the  field  tests;  namely,  that  marked  improve- 
ment can  be  made  on  this  soil  by  turning  under  legume  crops  where 
lime  has  been  applied.  Very  striking  results  appear  in  the  oat 
crop  in  1907. 

Of  interest  in  this  connection  is  another  series  of  pot-culture 
experiments,  with  soil  from  the  worn  hill  lands  of  Henry  County, 


FIELD    EXPERIMENTS   IN   THE   SOUTH 


487 


in  northwestern  Illinois,   which   furnish   additional   information 
concerning  the  general  need  of  nitrogen  for  these  hill  lands. 

The  plan  of  these  experiments,  the  soil  treatment  applied,  and 
the  results  obtained  are  all  shown  in  Table  98.1,  and  they  require  no 
further  comment. 

TABLE  98.1.   OAT  YIELDS  FROM  HENRY  COUNTY  (ILLINOIS)  SOIL 
Pot-culture  Experiments 


YELLOW  SILT  LOAM  HILL  LAND:  UPPER  ILLINOISAN  GLACIATION 

OAT  YIELDS 

Soil  Treatment  Applied                                           . 

(Grams  per  Pot) 

None      

cr 

Lime      

4 

Lime,  nitrogen     

4"% 

Lime,  phosphorus    

6 

Lime,  potassium    '  

5 

Lime,  nitrogen,  phosphorus  

78 

Lime,  nitrogen,  potassium     

46 

Lime,  phosphorus,  potassium     

5 

Lime   nitrogen   phosphorus   potassium                   .... 

38 

Nitrogen   phosphorus  potassium                              .... 

31 

None      .          ... 

c 

The  Mississippi  Experiment  Station  has  reported  in  Bulletin  108 
one  year's  experiments  (1906)  at  Holly  Springs  in  the  northwest 
part  of  that  state,  on  similar  worn  hill  land  where  fertilizers  were 
used  for  cotton,  corn,  and  cowpeas.  The  following  comments  are 
made: 

"Phosphates  hastened  the  maturity  of  cotton.  On  land  with  some  decaying 
organic  matter  in  it,  phosphate  alone  gave  good  results,  good  enough  to  make 
it  profitable.  Potash  alone,  or  in  combination  with  nitrogen  and  phosphates, 
gave  no  apparent  results.  Nitrogen  (cotton-seed  meal)  alone  gave  good  re- 
sults. Cotton-seed  meal  and  phosphates  mixed  gave  good  results." 

Similarly,  in  referring  to  the  corn  and  cowpeas,  the  following 
statements  are  made: 

"The  land  was  thin  upland.  A  drought  of  seven  weeks  obtained  when  the 
corn  was  young.  Where  the  soil  contained  organic  matter,  phosphates  alone 
gave  good  results.  Potash  alone,  or  in  combination,  failed  to  show  any  appre- 


488    INVESTIGATION   BY   CULTURE    EXPERIMENTS 

ciable  benefit.    Nitrogen  (cotton-seed  meal)  alone  gave  good  results.    A  mix- 
ture of  cotton-seed  meal  and  phosphates  gave  good  results." 

"The  fertilizer  test  with  peas  was  interfered  with  somewhat  by  the  October 
storm,  but  it  was  apparent  that  both  acid  phosphate  and  crude,  finely  ground 
rock  increased  the  growth  of  peas  in  a  marked  manner  —  apparently  doubling 
the  crop." 

In  Iowa  Bulletin  98,  1908,  are  reported  the  following  yields  of 
clover  hay  from  the  Leon  experiment  field  on  the  loess  and  till 
soils  of  southern  Iowa. 

TABLE  99.   SOUTHERN  IOWA  FIELD  EXPERIMENTS 


PLOT 

SOIL 

TREATMENT 

CLOVER  HAY 
PER  ACRE 

401  a 

Loess 

None    

2800  pounds 

402  a 

Loess 

Lime    

2400  pounds 

403  a 

Loess 

Manure    

4480  pounds 

404  d 

Loess 

Phosphorus  

^480  pounds 

40^  a 

Mixed  J 

Potassium      

2600  pounds 

406  a 

Mixed 

Phosphorus  

4750  pounds 

407  a 

Mixed 

Potassium     

2480  pounds 

408  a 

Mixed 

Phosphorus,  potassium    

4680  pounds 

409  a 
410  a 

Till 
Till 

Lime,  nitrogen,  phosphorus,  potassium  .     . 
Nitrogen,  phosphorus,  potassium  .... 

6560  pounds 
4600  pounds 

So6  b 

Till 

Lime    

3520  pounds 

<?O7  b 

Till 

Manure    

5120  pounds 

qo8  b 

Till 

Phosphorus  

5080  pounds 

zoo  b 

Till 

Manure    

4400  pounds 

Mixed  loess  and  till. 


The  following  comments  are  made  in  the  summary  of  Iowa 
Bulletin  98 : 

"Manure  applied  to  the  soil  at  the  rate  of  eight  tons  per  acre  was  decidedly 
beneficial  to  the  growth  of  clover." 

"Phosphorus  applied  to  the  soil  as  steamed  bone  meal  nearly  doubled  the 
yield  of  clover.  The  steamed  bone  meal  was  applied  at  the  rate  of  200  pounds 
per  acre." 

"Potassium,  applied  to  the  soil  as  potassium  sulfate,  did  not  increase  the 
clover  crop.  Neither  did  this  element  of  plant  food  prove  beneficial  when  used 
in  combination  with  phosphorus." 


FIELD    EXPERIMENTS    IN    THE    SOUTH 


489 


"Nitrogen,  applied  to  the  soil  as  dried  blood  in  combination  with  phosphorus 
and  potassium,  produced  an  increase  of  1800  pounds  of  clover  hay  per  acre 
over  that  grown  with  the  minerals  without  dried  blood." 

"Clover  should  be  grown  extensively  in  southern  Iowa  for  the  following 
reasons : 

"  a.  The  soils  of  this  section  of  the  state  are  deficient  in  nitrogen  and  organic 
matter. 

"  b.   These  soils  tend  to  wash  because  they  lack  humus." 

Georgia  field  experiments.  The  Georgia  Agricultural  Experiment 
Station  has  reported  a  large  number  of  fertilizer  experiments, 
especially  with  cotton  and  corn;  and  the  "  Georgia  rotation  " 
has  also  won  distinction  for  that  station.  This  is  a  three-year 
rotation,  as  follows: 

First  year.   Cotton. 

Second  year.  Corn,  with  cowpeas  seeded  at  the  last  cultivation 
and  harvested  for  seed  only,  the  vines  being  left  on  the  land  for 
soil  improvement. 

Third  year.  Winter  oats,  followed  by  a  regular  crop  of  cowpeas 
to  be  harvested  for  hay. 

For  this  rotation,  on  worn  uplands,  Director  Redding  recom- 
mended the  following  applications  per  acre  (Georgia  Bulletin 
72,  1906): 


CROPS 

NITROGEN 

PHOSPHORUS 

POTASSIUM 

VALUE 

For  cotton  

14 

20 

12 

$   C  22 

For  corn      

12 

IO 

14 

3  84 

For  oats      

17 

Ti 

21 

c  27 

For  cowpeas  (after  oats)    .     .     . 

15 

10 

2.40 

Total  for  three  years 

43 

53 

57 

$16.83 

The  fertilizer  materials  used  are  usually  cotton-seed  meal,  acid 
phosphate,  and  potassium  chlorid,  although  some  use  may  be  made 
of  sodium  nitrate,  and  kainit  may  replace  the  concentrated  salt. 

In  the  main  this  system  is  designed  to  apply  for  each  crop  the 
plant  food  which  it  needs,  without  much  reference  to  the  improve- 
ment of  the  soil,  although  farmers  are  urged  to  make  and  use  farm 
manure  so  far  as  possible,  and  the  statement  is  also  made  that 


490    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

"  there  are  no  fertilizers  that  will  give  better  results  on  cotton 
than  well-preserved  and  thoroughly  rotted  farmyard  manures, 
applied  very  early  in  the  season  of  preparation;  but  it  will  add  very 
much  to  the  effectiveness  of  such  manures  to  mix  with  them  a  lib- 
eral dose  of  acid  phosphate,  say  100  to  200  pounds  to  each  ton." 

It  should  be  kept  in  mind  that  the  upland  soils  of  Georgia  are  as 
a  rule  much  worn  and  extremely  deficient  in  active  organic  matter. 
Thus,  the  average  yield  of  corn  on  the  4^  million  acres  annually 
produced  is  n  bushels  per  acre,  for  the  10  years,  1899  to  1908. 

The  following  statements  regarding  distances  for  planting  corn 
occur  on  page  126  of  Georgia  Bulletin  72: 

"On  soils  of  still  less  capacity,  say  from  10  to  15  bushels  per  acre,  the  dis- 
tance should  be  still  greater,  say  18  to  24  square  feet  to  the  stalk,  or  2420  to  1815 
hills  to  the  acre.  Eighteen  square  feet  to  the  stalk  would  be  secured  by  spacing 
6  feet  by  36  inches,  or  5  feet  by  43  inches;  or  4  feet  3  inches  by  4  feet  3  inches. 
A  soil  that  would  produce  less  than  10  bushels,  with  good  seasons  and  very  light 
manuring,  is  not  fit  to  plant  in  corn." 

Many  of  the  Georgia  experiments  relate  to  a  study  of  the  effect 
of  varying  the  proportions  of  the  different  fertilizers,  as  illustrated 
in  Table  100  (Georgia  Bulletin  62,  page  93,  year  1903): 

TABLE  100.   GEORGIA  FERTILIZER  EXPERIMENTS  WITH  CORN 


PLOTS  OF  2  Rows  EACH 

POUNDS  APPLIED  PER  ACRE 

COST  OF 

CORN 

(Excepting    the    Unfertilized 
Plot,  4  Rows;     Rows  4  Feet 
Wide  by  209  Feet  Long) 

Sodium 
Nitrate 

Cotton- 
seed 
Meal 

Acid 
Phosphate 

Potassium 
Chiorid 

IZERS 
PER 

ACRE 

(Bushels 
per 
Acre) 

I,  6,  12,  17,  22     .      . 

17 

2OO 

ISI 

5-o 

$3.68 

18.2 

2,   7,  J3>  l8>  23     •       • 

17 

1  80 

182 

6.1 

3.68 

I8.5 

3,  8,  14,  19     ... 

17 

l62 

211 

7.0 

3.68 

I8.7 

4,  9,  15,  20     ... 

17 

146 

236 

7-9 

3.68 

!7-3 

5,  10,  16,  21   ... 

17 

J31 

259 

8.7 

3.68 

17.0 

ii  (unfertilized) 

ii.  6 

"The  plan  of  the  experiment  was  to  make  up  five  different  formulas  and  apply 
the  same  cost  value  of  each  different  formula  to  corresponding  successive  plots." 

The  same  section  of  land  (Div.  B,  Sect,  i  —  East)  was  used  for 
corn  in  1900,  and  the  report  for  that  year  states  that  "  no  plots 
were  left  unfertilized."  The  fertilizer  (including  53  pounds 


FIELD    EXPERIMENTS   IN   THE   SOUTH 


49 1 


cotton-seed  meal,  45  pounds  of  acid  phosphate,  and  2  pounds  of 
potassium  chlorid,  in  100  pounds)  was  applied  at  the  rate  of  200, 
400,  and  600  pounds  per  acre,  and  the  respective  yields  of  corn 
were  35.8,  37.0,  and  38.4  bushels  per  acre,  from  which  the  conclu- 
sion is  drawn  that  "  the  results  only  confirm  conclusions  repeatedly 
reached  in  previous  years  that  large  doses  of  commercial  fertilizers 
'  do  not  pay,'  as  a  rule,  when  applied  to  corn  on  upland." 

In  this  connection  the  following  rainfall  records  are  of  interest : 

TABLE  161.   RAINFALL  RECORDS  AT  EXPERIMENT,  GEORGIA 


YEARS 

MAY 

(Inches) 

JUNE 
(Inches) 

JULY 
(Inches) 

AUGUST 
(Inches) 

TOTAL  FOR 
THE  YEAR 

IQOO    
IQOI    
IOO2    . 

2.6l 
6.09 
.70 

12.02 

5-14 
I  QO 

6.84 
3.22 
I  ^4 

4-45 
6.27 

4  QQ 

62.33 
53-40 
47  O<\ 

1QO?    . 

6.47 

2.27 

2.28 

e  46 

48.78 

1QO4    . 

2.43 

.8? 

•2.64 

6.91 

20  06 

IQCX    . 

^8 

4.07 

3.OI 

2.02 

42.77 

1906    

2.21 

5-03 

4.17 

6.48 

44-74 

Averages,  1890  to  1906  .... 

3.08 

4.II 

5-OO 

5-93 

46.47 

The  yearly  records  for  1900  and  1904  are  the  extremes  for  the 
seventeen  years. 

In  Table  102  are  recorded  the  results  of  a  series  of  fertilizer  ex- 
periments with  cotton,  as  reported  in  Georgia  Bulletin  63. 

For  the  1904  corn  crop  fertilizers  were  applied  uniformly  to  all 
plots  (except  No.  u)  as  follows,  in  pounds  per  acre: 


SODIUM 
NITRATE 

COTTON- 
SEED MEAL 

ACID 
PHOSPHATE 

POTASSIUM 
CHLORID 

Section  4       
Section  5       

17 

21 

156 
IQ"> 

130 
162 

6.2 

8.0 

In  1906  cotton  was  grown  on  at  least  part  of  the  same  land  as  in 
1003,  with  the  plan  of  experiment  and  results  reported  in  Table 
103.  It  is  not  clear  whether  these  results  may  have  been  influenced 


492     INVESTIGATION   BY   CULTURE    EXPERIMENTS 

TABLE  102.   GEORGIA  FERTILIZER  EXPERIMENTS  WITH  COTTON 


POUNDS  APPLIED  PER  ACRE 

COST  OF 
.FERTIL- 

YIELD 

VALUE 

1904, 

EACH  PLOT 
(4  Rows  for  Plot  n?) 

Sodium 
Nitrate 
(With 
Seed) 

Cotton- 
seed 
Meal 

Acid 

Phos- 
phate 

Potas- 
sium 
Chlorid 

IZERS 
(Except 
Nitrate 
per 
Acre) 

COTTON 
(Pounds 
per 
Acre) 

CREASE 
AT  4^ 
PER 

POUND 

CORN 
(Bushels 
per 
Acre) 

NITROGEN  TEST:  DIVISION  B,  SECTION  4,  EAST,  1003 

1904 

I,  6,   12,   17,   22  . 

I5.6 

2OO 

250 

25.0 

$4.15 

1146 

$15.04 

20.3 

2,  7,  13,  l8>  23  . 

I5.6 

160 

306 

30.6 

4-15 

1  1  2O 

14.00 

2O.  I 

3,  8,  14,  19   .     . 

15-6 

120 

362 

362 

4-15 

1072 

12.08 

18-5 

4,  9,  15,  20    .     . 

15-6 

80 

418 

41.8 

4-15 

I°57 

11.48 

19-5 

5,  10,  16,  21  .     . 

I.S-6 

40 

474 

47-4 

4-15 

1042 

10.88 

19.6 

ii  (unfertilized) 

I5.6 

770 

20.1 

POTASSIUM  TEST:  DIVISION  B,  SECTION  4,  WEST,  1903 

I,  6,   12,   17,   22   . 

19-5 

195 

520 

65 

$6.50 

1503 

$22.13 

2,  7,  i3»  l8>  23  • 

19-5 

205 

547 

52 

6.50 

1438 

19.71 

3,  8,  T4,  19   •     • 

19-5 

215 

574 

39 

6.50 

1448 

20.16 

4,  9,  J5,  20   .     . 

19.5 

225 

601 

26 

6.50 

1488 

21.96 

5,  10,  16,  21  .     . 

19.5 

235 

628 

13 

6.50 

I451 

20.29 

ii  (unfertilized) 

19-5 

IOOO 

POTASSIUM  TEST:  DIVISION  B,  SECTION  5,  WEST,  1903 

I,  6,   12,   17,   22   . 

19.5 

195 

520 

65 

$6.50 

1556 

$24.93 

2,   7,  13,   l8>  23  . 

19.5 

205 

547 

52 

6.50 

1639 

28.66 

3,  8,  14,  19   .     . 

19-5 

215 

574 

39 

6.50 

1635 

28.48 

4,  9,  15,  20   .     . 

19-5 

225 

601 

26 

'6.50 

1667 

29.92 

5,  10,  16,  21  .     . 

19.5 

235 

628 

13 

6.50 

1693 

31.09 

ii  (unfertilized) 

19-5 

1002 

POTASSIUM  TEST:  AVERAGE,  1903 


1,6,  12,  17,  22  . 

19-5 

195 

520 

65 

$6.50 

1529 

$23.76 

25-3 

2,  7,  X3,  l8>  23  • 

19-5 

205 

547 

52 

6.50 

i538 

24.16 

25-5 

3,  8,  14,  19  .  . 

19-5 

215 

574 

39 

6.50 

i54i 

24.30 

25-3 

4,  9,  I5,  20  .  . 

19-5 

225 

601 

26 

6.50 

i578 

25.96 

21.7 

5.  10,  16,  21  .  . 

19-5 

235 

628 

T3 

6.50 

1572 

25.96 

24.0 

ii  (unfertilized) 

19-5 

IOOI 

22.2 

by  the  residual  effect  of  previous  applications  made  in  the  "  ni- 
trogen test,"  for  example  (Table  102). 

The  use  of  fertilizers  on  corn  in  Georgia,  if  profitable  at  all,  is 
evidently  made  possible  only  because  the  farm  price  of  corn  is 
very  high  (69 cents  as  a  ten-year  average),  and  the  profit  from  the 


FIELD    EXPERIMENTS   IN   THE   SOUTH 


493 


TABLE  103.   GEORGIA  FERTILIZER  EXPERIMENTS  WITH  COTTON 
(Division  B,  Sections  4  and  5,  East,  1906) 


FERTILIZER  FORMULA: 

Acid  phosphate      .     .     .   1000  Ib. 
Cotton-seed  meal        .     .     498  Ib. 
Potassium  chlorid      .     .       74  Ib. 

1572  'b- 

APPLIED  PER  ACRE 

RESULTS  PER  ACRE 

Mixed  Fertilizer 

Nitrate 
(With 
Seed) 

(Lb.) 

Yield  of 
Seed 
Cotton 

(Lb.) 

Increase 
Due  to 
Fertilizer 

(Lb.) 

Value 
of  In- 
crease 1 

Amount 
(Lb.) 

Cost 

12  plots  of  3  rows  each  . 
1  2  plots  of  3  rows  each   . 
12  plots  of  3  rows  each   . 
2  plots  of  4  rows  each   . 

4OO 
800 
I2OO 

$4.00 
8.00 

I2.OO 

22 
22 
22 
22 

1735 
1890 
2042 
1454 

28l 
436 

r-QQ 

5<55 

$10.11 
15.69 

21.17 

1  At  10  cents  a  pound  for  lint  and  70  cents  a  hundred  for  seed. 

use  of  fertilizers  is  found  in  the  cotton  crop,  which  it  should  be 
remembered  is  the  most  valuable  per  acre  of  all  the  general  field 
crops  grown  in  the  United  States  (potatoes  and  tobacco  being 
considered  as  truck  or  garden  crops) . 

As  an  average  seed  cotton  is  about  one  third  lint  and  two  thirds 
seed,  and  a  hundred-bushel  crop  of  corn  is  more  difficult  to  produce 
than  3000  pounds  per  acre  of  seed  cotton,  which  would  yield  1000 
pounds  (or  2  bales)  of  cotton  lint.  At  ten  cents  a  pound  for  cotton 
lint  and  70  cents  per  100  pounds  for  cotton  seed,  such  a  crop  would 
be  worth  $114  an  acre,  or  about  three  times  as  much  as  100  bushels  . 
of  corn  at  the  ten-year  average  price  in  the  corn  belt.  Georgia 
produces  less  than  200  pounds  of  cotton  lint  per  acre,  on  about  4^- 
million  acres,  the  annual  acreage  being  second  only  to  that  of  Texas. 

Judging  from  the  composition  of  the  residual  soils  of  Maryland, 
Tennessee,  and  Georgia,  and  from  the  statement  by  Director  Red- 
ding concerning  the  value  of  farm  manure  reenforced  with  acid 
phosphate,  it  seems  evident  that  large  use  of  ground  limestone  and 
legume  crops,  the  latter  to  be  plowed  under  either  directly  or  in 
farm  manure,  and  liberal  applications  of  phosphate,  constitute 
the  most  essential  factors  for  the  permanent  improvement  of  such 
land;  although,  under  the  present  condition  of  most  of  the  upland 
soils  of  Georgia  and  other  Southern  states,  profitable  use  can  no 
doubt  be  made  of  potassium,  at  least  until  the  supply  of  active 
organic  matter  is  greatly  increased,  and  especially  for  the  cotton 
crop,  which  pays  such  large  returns  for  a  comparatively  small 
increase  in  yield  per  acre. 


494    INVESTIGATION   BY   CULTURE   EXPERIMENTS 


TABLE  104.   ALABAMA  FIELD  EXPERIMENTS,  1905-1908 
Averages  per  Acre  per  Annum 


LAU- 

DER- 

CULL- 

CHIL- 

Au- 

TAU- 

MONT- 
GOM- 

TALLA- 

MACON 

o 

DALE 

MAN 

TON 

GA 

ERY 

Co., 

A 

PLANT  FOOD  APPLIED 

COST 

Co., 
GRAY 
SILT 

Co., 
GRAY 

SANDY 

Co., 
GRAY 
SANDY 

Co., 
RED- 
DISH 

Co., 
BLACK 
OK  RED 

GRAY 

SANDY 

DARK 
GRAY 
SANDY 

fc 

LOAM 

UP- 

SOIL 

SANDY 

PRAI- 

LOAM 

SOIL 

LAND 

SOIL 

RIE 

No.  of  Years  in  Trial 

4 

3 

4 

3 

3 

4 

3 

SEED  COTTON  PER  ACRE,  POUNDS 


I 
a 

Nitrogen  (14  Ib.)  l  .     . 
Phosphorus  (16  Ib.)    . 

$2.50 
1.68 

649 
678 

442 
571 

647 
573 

.0, 

888 
789 

f\nf\ 

464 

484 

635 

587 

468 
625 

,.QT 

4 

5 

6 

7 
8 

(i 

Potassium  (20  Ib.)  .     . 
Nitrogen,  phosphorus  . 
Nitrogen,  potassium    . 
Phosphorus,  potassium 

Unfertilized  .... 
NPK  

1.50 
4.18 
4.00 
3.18 

s  68 

374 
796 

1295 
886 

695 

387 

QI7 

320 

452 
721 

576 
614 

291 

68? 

4°3 
646 

657 
618 

57° 

437 
778 

70O 
829 

801 
716 

679 

880 

576 

503 
628 
644 

382 

74O 

433 
610 

651 
663 
626 

358 

74.2 

634 
728 

595 
610 

522 

Q2S 

10 

NPK  (*)  . 

A  Q7 

80  1 

7IO 

718 

808 

689 

7QO 

89? 

INCREASE  OF  SEED  COTTON  PER  ACRE,  POUNDS 


T 

N  

$2.  SO 

27S 

122 

163 

212 

62 

2O  2 

—IT. 

7 

P  

i  68 

204 

2SI 

O4 

II  -2 

82 

1C  A 

I4S 

4 

K  

I.  "CO 

4IQ 

138 

172 

27 

178 

IQ2 

I4S. 

e 

NP   

4.18 

Ql6 

412 

IQ2 

IS2 

IOQ 

248 

27,1 

6 

NK   

4-OO 

SO4 

274 

163 

124 

238 

27=; 

GO 

7 

PK   

3.18 

711 

317 

124 

-58 

2S8 

2C^ 

96 

n 

NPK  

5.68 

"?3O 

7Q2 

^41 

2O  I 

7C7 

^84 

4O3 

Tri 

NPK(i)  . 

4.  Q7 

414 

410 

280 

1  2O 

307 

472 

771 

VALUE  OF  INCREASE  PER  ACRE  (AT  3.2  c.  PER  LB.) 


T 

N    

$2  SO 

88c 

7.   OO 

S  23 

6  78 

I.  QQ 

6.46 

—.41 

0 

P     

i  68 

97-2 

804 

3  O2 

T  6?, 

2  63 

4.  04 

.63 

A 

K    

I  SO 

I  3  41 

4  41 

S  40 

.7S 

S.7I 

6.13 

4.64 

C 

NP  ....... 

4  18 

20  31 

13  22 

6  16 

4  87 

3.40 

7.<K 

7.  30 

6 

NK  

4  oo 

16  14 

8  76 

S  2O 

3  06 

763 

8.80 

2.88 

7 

PK  

T,  18 

90S 

10  16 

3  06 

I  21 

8.24 

8.0Q 

3.08 

o 

NPK   

s  68 

1  6  96 

12  S7 

10  91 

6.44 

11.47 

I2.7O 

12.89 

TO 

NPK  (i)  

4  Q2. 

I  2  2S 

I  3  42 

898 

4  14 

Q.8l 

13.84 

u.86 

1  The  nitrogen  is  regularly  applied  in  200  Ib.  of  cotton-seed  meal  (at  $25  a  ton), 
which  also  contains  about  2  Ib.  of  phosphorus  and  3  Ib.  of  potassium.  The  phos- 
phorus is  applied  in  240  Ib.  of  acid  phosphate  (at  $14  a  ton)  and  the  potassium  in 
200  Ib.  of  kainit  (only  100  Ib.  on  plot  10),  costing  $15  a  ton.  These  are  the  prices 
reported  in  Alabama  Bulletin  145,  February,  1909. 


FIELD    EXPERIMENTS   IN   THE   SOUTH  495 

Alabama  field  experiments.  The  Alabama  Agricultural  Experi- 
ment Station  has  reported  the  results  of  fertilizer  experiments 
with  cotton  on  the  common  soils  in  several  different  counties.  In 
Table  104  are  given  three-year  or  four-year  averages  from  seven 
different  counties.  In  computing  the  value  of  the  increase,  Direc- 
tor Duggar  allows  $14  a  ton  for  cotton  seed  and  10  cents  a  pound 
for  lint,  the  average  price  for  the  five  years,  1904-1908.  He  also 
assumes  that  the  seed  cotton  is  one  third  lint,  and  thus  counts  the 
cotton  seed  at  3.8  cents  a  pound,  or  at  3.2  cents  a  pound  for  the 
increase,  after  allowing  .6  cent  a  pound  for  picking  and  ginning. 

These  results  especially  emphasize  two  facts :  first,  that  the  soils 
are  very  poor,  and  second,  that  the  cotton  crop  is  so  valuable  that 
even  small  increases  in  yield  justify  large  expenditures  for  fertil- 
izers. As  an  average  of  the  48  different  tests,  the  yield  of  the  un- 
fertilized land  is  less  than  150  pounds  of  cotton  lint  per  acre. 

With  few  exceptions,  every  kind  of  fertilizer  has  more  than  paid 
its  cost,  and  as  a  rule  every  addition  has  increased  the  profit  per 
acre,  the  largest  profit  being  secured  from  the  most  heavily  fer- 
tilized land.  It  should  be  kept  in  mind,  however,  that  as  an  average 
a  pound  of  Alabama  seed  cotton  is  worth  five  times  as  much  as  a 
pound  of  Illinois  corn.  Very  probably  the  200  pounds  of  kainit 
have  been  more  effective  than  50  pounds  of  potassium  chlorid 
would  have  been,  because  these  soils  are  as  a  rule  very  deficient 
in  active  organic  matter,  and  under  such  conditions  the  larger 
quantity  of  soluble  salt  is  likely  to  become  more  effective. 

The  average  annual  rainfall  of  Alabama  is  given  as  51  inches. 
The  monthly  rainfall  from  May  to  September  averages  more  than 
4  inches.  Of  the  20  records  for  these  months  during  the  four  years, 
1905-1908,  the  lowest  was  2.42  inches,  and  only  three  others  were 
below  3.44  inches.  The  highest  was  8.50  inches,  with  only  two 
others  above  5.51  inches. 

Louisiana  field  experiments.  The  Louisiana  Agricultural  Experi- 
ment Station  has  conducted  a  series  of  field  experiments  since 
1889,  on  the  experiment  farm  at  Calhoun,  in  the  northern  part  of 
the  state,  on  hill  land  originally  covered  with  pine  trees.  The  soil 
had  become  much  exhausted  from  70  or  80  years  of  previous  cotton 
culture. 

The  field  consists  essentially  of  six  one-acre  plots  arranged  in 


496    INVESTIGATION   BY   CULTURE    EXPERIMENTS 


three  series  of  two  plots  each,  one  unfertilized  and  the  other  fer- 
tilized chiefly  with  compost  made  as  described  below.  A  three- 
year  rotation  has  been  practiced  as  follows : 

First  year Cotton. 

Second  year Corn  and  cowpeas. 

Third  year Oats  followed  by  cowpeas. 

By  having  three  series,  each  crop  may  be  represented  every  year. 

For  cotton,  30  bushels  per  acre  are  applied  of  a  compost  made  by 
mixing  2  tons  of  acid  phosphate  with  100  bushels  each  of  stable 
manure  and  cotton  seed.  For  corn,  30  bushels  per  acre  are  used  of 
a  compost  made  with  one  ton  of  acid  phosphate  mixed  with  100 
bushels  of  stable  manure  and  100  bushels  of  cotton  seed.  After 
preparing  the  compost,  it  is  allowed  to  ferment  for  two  or  three 
weeks,  then  thoroughly  mixed,  and  after  standing  a  few  days 
longer  is  ready  for  use. 

The  oats  are  fertilized  with  200  pounds  of  cotton-seed  meal  and 
100  pounds  of  acid  phosphate  per  acre,  and  the  cowpeas  are  also 
fertilized  by  applying  50  pounds  of  acid  phosphate  and  50  pounds 
of  kainit  per  acre. 

The  following  average  results  are  reported  by  Director  Dodson 
in  Louisiana  Bulletin  in,  September,  1908: 

TABLE  104.1.   LOUISIANA  FIELD  EXPERIMENTS  AT  CALHOUN:    YIELDS  PEE 
ACRE:    FROM  19  YEARS'  RECORDS 


SERIES 

SEED  COTTON  (Lb.) 

CORN  (Bu.) 

OATS  (Bu.) 

Unfertil- 
ized 

Fertilized 

Unfertil- 
ized 

Fertilized 

Unfertil- 
ized 

Fertilized 

A      

459 

SO? 
432 

1555 

1811 
H75 

9-7 

8.9 
9.6 

3°-4 
3°-5 
33-5 

22.1 
12.4 
T4.9 

49-3 
32.2 
44.1 
41.8 

B      

c    

Average      .     .     . 

466 

15*4 

9-4 

3M 

16.4 

Increase 

1048  lb. 
$39-82 
5-5o 



22.0  bu. 
$11.00 

6.00 

25.4  bu 
$11.43 
2-95 

Value  l  of  increase     .     .     . 
Cost  of  fertilizer    .... 

1  Computed  at  Louisiana  prices,  3.8  cents  a  pound  for  seed-cotton,  50  cents  a 
bushel  for  corn,  and  45  cents  a  bushel  for  oats. 


FIELD   EXPERIMENTS   IN   THE   SOUTH  497 

The  cost  of  fertilizer  is  given  as  estimated  by  Director  Dodson. 
No  report  is  made  of  the  yield  of  cowpeas. 

In  1889  the  increases  produced  by  the  fertilizing  were  only  301 
pounds  of  seed  cotton,  4.7  bushels  of  corn,  and  4.8  bushels  of  oats; 
but  in  the  second  year  the  increases  were  1227  pounds  of  seed  cot- 
ton, 19.7  bushels  of  corn,  and  25.3  bushels  of  oats,  which  are  prac- 
tically as  great  as  the  averages  for  the  entire  period. 

The  1514  pounds  of  seed  cotton  would  yield  about  1000  pounds 
of  cotton  seed,  or  about  30  bushels,  which  would  not  be  sufficient 
to  make  the  compost  for  one  acre  of  cotton  and  one  acre  of  corn, 
counting  the  shrinkage  in  volume  during  the  three  or  four  weeks 
allowed  for  fermentation;  and,  besides  the  whole  seed  used  in  the 
compost,  200  pounds  of  cotton-seed  meal  are  used  for  the  oats. 
On  the  other  hand,  the  corn,  oats,  and  cowpea  crops  produced  on 
the  fertilized  land  would  certainly  make  much  more  manure  than 
was  used  in  these  experiments,  so  that,  with  little  modification,  this 
system  could  be  made  independent  and  permanent  as  well  as  more 
profitable. 

The  following  significant  statements  are  made  by  Professor 
Dodson : 

"When  we  sell  cotton  lint,  we  sell  cellulose,  composed  of  hydrogen,  oxygen, 
and  carbon  (CoHioOs),  which  was  derived  from  the  air  and  water.  When  we 
sell  our  seed,  we  sell  the  fertility  of  the  land,  as  the  Northern  and  Western  farmer 
does  when  he  sells  his  grain.  The  oil,  however,  has  no  fertilizing  value,  being, 
like  the  lint,  composed  of  elements  taken  from  the  air  and  water,  and  cannot 
be  used  again  by  the  cotton  plant ;  so  if  we  sell  only  the  lint  and  the  oil,  return- 
ing the  hulls  and  the  meal  to  the  land,  we  have  not  reduced  the  fertility  ap- 
preciably." 

With  liberal  applications  of  ground  limestone  where  needed,  and 
large  use  of  the  most  suitable  legume  crops  turned  under,  either 
in  farm  manure  or  in  green  manures,  including  not  only  cowpeas, 
but  also  red  clover,  alsike  clover,  crimson  clover,  Japan  clover 
(Lespedeza),  vetch,  velvet  beans,  and  even  alfalfa  under  proper 
conditions,  and  with  plenty  of  phosphorus,  either  as  acid  phosphate, 
steamed  bone  meal,  or  fine-ground  raw  rock  phosphate,  it  seems 
very  certain  that  the  cotton  and  grain  crops  of  the  South  could  be 
increased  even  much  above  the  yields  maintained  for  20  years  in 
these  valuable  experiments  by  the  Louisiana  Station. 


498    INVESTIGATION   BY   CULTURE   EXPERIMENTS 


It  is  highly  probable  that  a  liberal  use  of  kainit  would  also  be 
profitable  for  a  time  in  getting  such  systems  under  way  on  the  more 
depleted  soils.  It  must  be  kept  in  mind  that  crops  must  be  grown 
before  either  farm  manure  or  green  manure  can  be  plowed  under. 

NOTES.  On  the  Coastal  Plains,  especially  from  North  Carolina  to  Florida, 
are  some  extensive  areas  of  very  sandy  soils.  For  truck  farming  these  be- 
come very  productive  where  heavily  fertilized,  but  they  are  commonly  too 
poor  to  be  used  profitably  for  general  farming.  Thus,  Bulletin  68  of  the 
Florida  Agricultural  Experiment  Station  contains  40  chemical  analyses  of 
the  ordinary  very  sandy  loams  upon  which  nearly  all  of  the  pineapples  pro- 
duced in  that  state  are  grown,  and  in  commenting  upon  these  soils  the 
authors  say,  "  Few  of  the  soils  would  be  able  to  produce  more  than  two  or 
three  crops  of  pineapples  if  all  the  plant  food  present  were  available." 

This  statement  is  well  supported  by  analyses  of  samples  of  soil,  representative 
of  large  areas  in  Southern  Florida,  which  were  collected  by  Professor  F.  H. 
King  in  1910  and  analyzed  with  the  following  results: 

AVERAGE  POUNDS  IN  2  MILLION  OF  SOIL 


COUNTY 

SOIL  STRATUM 

TOTAL  NITROGEN 

TOTAL 
PHOSPHORUS 

TOTAL 
POTASSIUM 

De  Sota     .     .     . 
De  Sota     .     .     . 

ist  Foot 
2d  Foot 

970 
34° 

trace 
trace 

2320 
1830 

Lee  
L,ee  

ist  Foot 
2d  Foot 

2560 
840 

39° 
160 

320 
1160 

Two  analyses  of  the  peat  or  "muck"  soil  from  the  Everglades  swamps  of 
Florida  show  the  following  amounts  per  million : 


Nitrogen  

26,000 

^I,2OO 

Phosphorus  

o^o 

no 

Potassium      

I.^OO 

2.4IO 

Magnesium   

I.T.IO 

I.44O 

Calcium    

27.2SO 

27.O7O 

Iron      

12,370 

8.  400 

Sulfur  

2,4?O 

4,^60 

Sodium  chlorid       

8,=;oo 

i.  080 

Organic  matter  and  combined  water     .     . 
Silica  and  insoluble  silicates     

909,700 
10,940 

908,000 
20,100 

While  these  "  muck  "  or  peat  soils  are  rich  in  nitrogen  and  calcium,  they 
are  either  poor  or  extremely  poor  in  phosphorus,  potassium,  and  magnesium. 


CHAPTER  XXIV 


MINNESOTA    SOIL   INVESTIGATIONS 

BECAUSE  they  have  been  so  widely  quoted  in  the  agricultural 
press  of  the  central  West,  and  even  in  text-books  on  soils  and  fer- 
tilizers, it  seems  especially  important  to  give  in  some  detail  the  re- 
sults of  field  and  laboratory  experiments  conducted  by  the  Minne- 
sota Agricultural  Experiment  Station  since  1892. 

TABLE  105.  MINNESOTA  SOIL  INVESTIGATIONS 
(a)  Crop  Yields  per  Acre  in  Bushels  or  Tons 


YEAR 

PLOT  No*,  i 
WITHOUT  MANURE, 
WHEAT  GROWN  CON-< 

PLOT  No.  2 
8  LOADS*  OF  MANURE 
IN  FIVE-YEAR  ROTATION 

PLOT  No.  3 
8  LOADS  l  OF  MANURE 
IN  FOUR-YEAR  ROTATION 

1893 

I2-3J 

Wheat  .     . 

13.7    bu. 

Oats       .     . 

41.6    bu. 

1894 

8.9 

Clover  .     . 

2.16  tons 

Clover    . 

1.18  tons 

!895 
1896 

17-3 
14.1 

^  Av.  14.7 

Wheat  .     . 
Oats      .     . 

22.0    bu. 
31.4    bu. 

Barley    .     . 
Corn  . 

42.5    bu. 
66.  7    bu. 

1807 

10.2 

Wheat  .     . 

14.2    bu. 

Corn  . 

33.7    bu. 

1898 

25.2 

Clover  .     . 

1.41  tons 

Oats  .     .     . 

76.4    bu. 

1899 

17.6 

Wheat  .     . 

19.5    bu. 

Clover     .     . 

1.86  tons 

1900 

18.8 

Wheat  .     . 

24.4    bu. 

Barley    .     . 

28.3    bu. 

1901 

16.2 

Oats      .     . 

58.7    bu. 

Corn  . 

40.6    bu. 

1902 

18.3 

Corn 

(?) 

Oats  .     .     . 

80.0    bu. 

1903 

18.6 

Wheat  .     . 

30.0    bu. 

Clover    . 

4.70  tons 

1904 

13-7 

Clover  . 

3.98  tons 

Barlev    .     . 

40.0    bu. 

Total  clover  in  1  2  years 

Clover  . 

7-55  tons 

Clover    . 

7.  74  tons 

(b)  Nitrogen  2  in  Soil  per  Acre  9  Inches  Deep 


YEARS 

TOTAL  (Lb.) 

Loss  (Lb.) 

TOTAL  (Lb.) 

Loss  (Lb.) 

TOTAL  (Lb.) 

Loss  (Lb.) 

1892 
1896 
1900 
1904 

5400 

47*5 
423° 
3955 

5400 

5645 
4840 
4690 

5200 
5300 
4870 
5480 

685 
•   485 
275 

245  (gain) 
805  (loss) 
150  (loss) 

160  (gain) 
490  (loss) 
615  (gain) 

Total   loss  in  8 

years,  1896  to 
1904     .     .     . 

760 

955  (loss) 

125  (gain) 

1  Evidently  these  loads  of   manure  weighed  1200  Ib.  each,  making   9600  lb., 
or  less  than  5  tons,  per  acre.  —  C.  G.  H. 

2  Based  upon  the  statement  that  .221  per  cent  of  nitrogen  is  equivalent  to  5400 
lb.  of  nitrogen  per  acre. 

499 


500     INVESTIGATION   BY   CULTURE   EXPERIMENTS 

Probably  no  agricultural  investigations  have  ever  been  reported 
which  have  brought  forth  more  error  and  confusion  in  the  public 
mind  than  these  experiments. 

While  they  are  carried  on  in  part  to  determine  the  effect  upon 
wheat  yields  of  continuous  wheat  culture  upon  the  same  land,  the 
information  secured  only  shows  that  some  factor  or  factors,  other 
than  the  continuous  growing  of  wheat,  have  thus  far  exerted  pre- 
dominating influence  upon  the  production  of  wheat. 

The  figures  for  nitrogen  given  in  Table  105  are  based  upon  the 
percentages  reported  from  time  to  time  by  Professor  Harry  Snyder 
in  Minnesota  Bulletins  53,  70,  and  89,  and  upon  his  later  statement 
that  all  samples  have  been  taken  to  a  depth  of  9  inches. 

Thus,  in  Minnesota  Bulletin  53,  June,  1897,  we  read: 

"Plots  i,  2,  and  3  were  4  rods  by  5  rods." 

"On  plot  No.  i,  wheat  was  grown  continuously.  On  plot  No.  2,  wheat  was 
grown  in  1893,  and  clover  was  sown  with  the  wheat;  a  crop  of  clover  was  har- 
vested in  1894.  In  the  fall  of  1894  the  clover  sod  was  plowed  under,  and  the 
next  year  a  crop  of  wheat  was  grown,  and  in  1896  a  crop  of  oats.  It  is  the  plan 
to  apply  manure  at  this  point  and  produce  a  crop  of  corn,  and  to  follow  the 
corn  with  wheat  and  clover,  the  complete  rotation  being:  (i)  wheat  and 
clover,  (2)  clover,  (3),  wheat,  (4)  oats,  (5)  corn  and  manure. 

"Plot  No.  3.  After  the  wheat  crop  in  1892,  oats  were  grown,  and  clover 
was  seeded  with  the  oats,  and  in  1894  a  crop  of  clover  was  harvested.  The 
clover  sod  was  fall-plowed  and  the  next  year  barley  was  grown.  After  the  barley 
crop  the  plot  received  1200  pounds  of  manure,  and  the  next  year  was  seeded  to 
corn,  the  complete  rotation  being:  (i)  oats  and  clover,  (2)  clover,  (3)  barley, 
(4)  corn  and  manure." 

"In  plots  Nos.  i  and  2  there  was  originally  present  in  the  soil  .221  per  cent  of 
nitrogen,  equivalent  to  5400  pounds  of  nitrogen  per  acre  to  a  depth  of  9  inches. 
After  four  years'  continuous  cropping  of  wheat,  plot  No.  i  yielded  .193  percent 
of  nitrogen,  a  loss  of  .028  per  cent,  equivalent  to  an  annual  loss  of  171  pounds 
of  nitrogen  per  acre." 

"In  plot  No.  2,  where  clover  has  been  grown  in  a  rotation,  there  has  been  a 
gain  of  nitrogen.  At  the  end  of  the  rotation  there  was  .231  per  cent  nitrogen 
present  in  the  soil.  On  this  plot  clover  was  grown,  and  the  second  growth  of 
clover  was  plowed  under  for  green  manure.  The  total  nitrogen  removed  in  the 
crops  amounted  to  178  pounds.  Notwithstanding  the  fact  that  larger  crops 
have  been  grown  on  this  plot  than  on  No.  i,  there  has  been  a  gain  of  245  pounds 
of  nitrogen  in  the  four  years'  rotation,  in  addition  to  the  nitrogen  removed  in  the 
crops." 

"The  soil  (of  plot  3)  originally  contained  .211  per  cent  of  nitrogen.  At  the 
close  of  the  rotation  it  contained  .218  per  cent  of  nitrogen.  The  amount  of 


MINNESOTA   SOIL   INVESTIGATIONS  501 

nitrogen  removed  in  the  crops  during  the  four  years  amounted  to  204  pounds. 
The  gain  in  nitrogen  has  been  at  the  rate  of  about  40  pounds  per  acre." 

Four  years  later,  in  Minnesota  Bulletin  70,  May,  1901,  we  find 
the  following  statements: 

"Plots  Nos.  i  and  2  contained,  at  the  beginning  of  the  experiments  in  1892, 
.221  per  cent  of  nitrogen,  while  plots  Nos.  3,  4,  5,  and  6  contained  .211  per 
cent.  It  is  estimated  that  an  acre  of  the  soil  of  plots  Nos.  i  and  2,  to  a  depth 
of  9  inches,  would  contain  approximately  7700  pounds  of  nitrogen,  while  the 
remaining  plots  would  contain  approximately  7400  pounds.  At  the  end  of  the 
first  four  years  of  continuous  wheat  cultivation,  plot  No.  i  contained  .193  per 
cent  of  nitrogen;  a  loss  of  .028  per  cent,  equivalent  to  an  annual  loss  of  171 
pounds  of  nitrogen  per  acre.  At  the  end  of  the  second  period  of  four  years, 
the  soil  contained  .173  per  cent  of  nitrogen. 

"At  the  beginning  of  the  experiment  in  1892,  plot  No.  2  contained  .221  per 
cent  of  nitrogen.  At  the  end  of  eight  years,  after  the  removal  of  five  crops  of 
wheat,  two  of  clover  and  one  of  oats,  or  six  grain  crops  and  two  clover  crops,  the 
soil  contained  .198  per  cent  of  nitrogen." 

"On  plot  No.  3,  oats,  clover,  barley,  and  corn  have  been  grown.  The  soil 
of  this  plot  originally  contained  .211  per  cent  of  nitrogen.  At  the  end  of  eight 
years  the  soil  contained  .198  per  cent  of  nitrogen."  (See  pages  254-256  in  Min- 
nesota Bulletin  70.) 

In  Minnesota  Bulletin  89  (January,  1905)  we  find  the  following 
statements: 

"While  21.7  per  cent  of  the  soil  nitrogen  was  lost  during  the  first  eight  years 
of  continuous  wheat  culture,  only  5.71  per  cent  was  lost  during  the  four  years 
following." 

"  On  plot  No.  2  a  rotation  consisting  of  wheat,  clover,  wheat,  oats,  and  corn 
and  manure  has  been  followed,  with  some  modifications  because  of  climatic 
conditions.  The  soil  of  this  plot  contained  originally  about  the  same  amount 
of  nitrogen  as  plot  No.  i,  namely,  7700  pounds  per  acre  to  a  depth  of  one  foot.1 
At  the  end  of  twelve  years  the  soil  contained  6725  pounds." 

"The  soil  of  plot  number  three  originally  contained  about  7400  pounds  per 
acre  of  nitrogen.  At  the  close  of  the  first  period  of  four  years,  the  soil  showed 
a  slight  gain  in  nitrogen,  and  at  the  end  of  eight  years,  a  slight  loss.  During 

1  On  page  38  of  Minnesota  Bulletin  102  (September,  1907)  a  correction  note  states 
that  this  should  read:  "to  the  depth  of  three  fourths  of  one  foot, "  and  consequently 
it  must  be  assumed  that  the  "7700  pounds"  should  read  "5400  pounds"  (less 
than  75  per  cent),  and  that  corresponding  corrections  should  be  made  throughout. 
According  to  the  data  (5400  pounds  for  .221  per  cent)  the  soil  of  an  acre  to  a  depth 
of  9  inches  would  amount  to  about  2,450,000  pounds,  which  agrees  with  Professor 
Snyder's  statement  that  the  soil  weighed  about  75  pounds  per  cubic  foot  (page  9, 
Minnesota  Bulletin  53).  — C.  G.  H. 


502 

the  third  four-year  period  also  there  was  a  slight  gain  of  nitrogen,  and  at  the  end 
of  twelve  years,  the  soil  contained  about  7800  pounds  per  acre,  showing  that 
where  clover  was  grown  once  in  four  years  in  a  rotation  with  grains,  and  one 
dressing  of  farm  manure  was  applied  to  the  corn  at  the  rate  of  eight  loads  per 
acre,  the  nitrogen  content  of  the  soil  has  been  maintained  unimpaired."  (See 
pages  193  to  195  in  Minnesota  Bulletin  89.) 

In  his  excellent  and  widely  used  text  and  reference  book  on 
"  Fertilizers,"  Doctor  Voorhees,  Director  of  the  New  Jersey  Ag- 
ricultural Experiment  Station,  makes  the  following  statements: 

"Another  source  of  natural  loss  of  nitrogen  is  its  escape  from  the  soil  as  gas 
into  the  atmosphere.  This  is  due  to  the  oxidation  of  the  vegetable  matter,  or 
to  'denitrification,'  which  takes  place  very  rapidly  where  soils  rich  in  vegetable 
matter  are  improperly  managed.  The  possibilities  of  loss  in  this  direction  are 
strongly  shown  by  investigations  carried  out  at  the  Minnesota  Experiment 
Station  on  '  the  loss  of  nitrogen  by  continuous  wheat  raising'  (Minnesota  Bulle- 
tin 53).  The  results  of  these  studies  show  that  the  total  loss  of  nitrogen  an- 
nually was  far  greater  than  the  loss  due  to  cropping.  In  other  words,  by  the 
system  of  continuous  cropping,  which  is  universally  observed  in  the  great 
wheat  fields  in  the  Northwest,  there  was  but  24.5  pounds  of  nitrogen  removed 
in  the  crop  harvested,  while  the  total  loss  per  acre  was  171  pounds,  or  an  excess 
of  146  pounds,  a  large  part  of  which  loss  was  certainly  due  to  the  rapid  using  up 
of  the  vegetable  matter  by  this  improvident  method  of  practice.  Whereas,  on 
the  other  hand,  when  wheat  was  grown  in  a  rotation  with  clover,  the  gain  in 
soil  nitrogen  far  exceeded  that  lost  or  carried  away  by  the  crop." 

These  statements  faithfully  represent  the  teaching  of  Minnesota 
Bulletin  53,  except  as  to  the  manner  in  which  the  nitrogen  escapes. 
With  the  more  recent  accumulated  information  concerning  soil 
bacteria,  to  which  Doctors  Voorhees  and  Lipman  of  the  New  Jersey 
Station  have  largely  contributed,  a  revision  of  Voorhees'  "  Fer- 
tilizers" probably  will  not  ascribe  any  large  part  of  the  loss  to 
denitrification. 

In  his  own  text-book  on  "  Soils  and  Fertilizers,"  published  in 
June,  1905,  Professor  Snyder  makes  'the  following  statements 
(page  112): 

"A  rotation  of  wheat,  clover,  wheat,  oats,  and  corn  with  manure  will  leave  the 
soil  at  the  end  of  the  period  of  rotation  in  better  condition  as  regards  nitrogen 
than  at  the  beginning.  These  facts  are  illustrated  in  the  following  table :  l 

1  Minnesota  Agricultural  Experiment  Station  Bulletin  No.  53. 


MINNESOTA   SOIL   INVESTIGATIONS  503 


"  CONTINUOUS  WHEAT  CULTURE 

Nitrogen  in  soil  at  beginning  of  experiment 0.221  per  cent 

Nitrogen  at  end  of  5  years'  continuous  wheat  cultivation  .     .     0.193  Per  cen* 
Loss  per  annum  per  acre  (in  crop  24.5,  soil  146.5)  ....         171  pounds 

"ROTATION  OF  CROPS 

Nitrogen  in  soil  at  beginning  of  rotation 0.221  per  cent 

Nitrogen  at  close  of  rotation 0-231  per  cent 

Gain  to  soil  per  annum  per  acre        61  pounds 

Nitrogen  removed  in  crops  per  annum 44  pounds 

"It  is  to  be  regretted  that  in  the  cultivation  of  large  areas  of  land  to  staple 
crops,  as  wheat,  corn,  and  cotton,  the  methods  of  cultivation  followed  are  such 
as  to  decrease  the  nitrogen  content  and  crop-producing  power  of  the  soil  when 
this  could  be  prevented." 

Unquestionably  the  greatest  practical  problem  that  confronts 
the  average  American  farmer  is  to  maintain  the  humus  and  nitro- 
gen content  of  the  soil,1  and  the  author  cannot  be  true  to  the  stu- 
dent and  neglect  to  present  the  determined  facts  in  a  matter  of  so 
vital  consequence  to  American  agriculture.  It  will  be  noted  that 
the  data  just  quoted  relate  only  to  the  first  four  years  (not  five 
years  or  twelve  years)  of  these  Minnesota  experiments,  where  no 
manure  had  been  used.  As  a  matter  of  fact,  the  published  bulletins 
show  that  wheat  (not  corn)  was  grown  on  plot  2  the  fifth  year. 
The  subsequent  data  show,  however,  that  during  the  second  four 
years  (presumably  with  manure  added)  there  was  a  loss  of  nitrogen 
from  plot  2  amounting  to  .033  per  cent  (.231-.  198),  or  about  800 
pounds  per  acre  (counting  only  2,450,000  pounds  of  soil  for  a  depth 
of  9  inches) ,  and  during  the  same  four  years  the  data  for  the  other 
rotation,  with  manure  applied,  show  a  loss  of  490  pounds  of  nitro- 
gen per  acre  from  plot  3. 

The  only  point  the  author  would  emphasize  is  that  these  Min- 
nesota investigations  have  not  yet  furnished  sufficient  data  to 

1  It  is  a  very  simple  matter  to  maintain  or  materially  increase  the  phosphorus 
content.  One  ton  of  raw  rock  phosphate,  costing  from  $7  to  $10  (depending  on 
distance  of  shipping),  and  containing,  say,  250  pounds  of  phosphorus,  will  supply 
more  of  that  element  to  an  acre  of  land  than  would  be  removed  in  12  years  if  the 
average  crops  were  100  bushels  of  corn  (grain  only  removed),  100  bushels  of  oats, 
50  bushels  of  wheat,  and  4  tons  of  clover. 


504    INVESTIGATION   BY   CULTURE    EXPERIMENTS 

determine  the  conditions  under  which  the  supply  of  nitrogen  will 
be  maintained.  Of  course  it  requires  no  new  investigations  to  show 
that  sufficiently  large  applications  of  manure  will  maintain  the 
supply  of  nitrogen,  whether  the  crops  are  rotated  or  grown  continu- 
ously, as  at  Rothamsted,  with  wheat,  barley,  or  mangels. 

NOTE.  In  passing  from  this  extended  consideration  of  the  field  experi- 
ments conducted  in  various  parts  of  the  United  States,  the  reader  will  per- 
haps be  interested  to  note  the  following  correspondence  in  relation  to  the 
application  of  science  to  practical  farming: 

"  GILMAN,  ILLINOIS,  November  23,  1909. 

"  DEAR  DOCTOR  HOPKINS  :  —  Am  sending  you  a  few  comparative  figures, 
which  I  trust  may  interest  you.  I  have  no  doubt  you  can  see  more  in  them 
than  I  can,  but  I  see  much  that  gives  encouragement  for  the  future: 

"  COMPARATIVE  YIELDS  OF  CORN  FROM  TREATED  AND  UNTREATED 
LAND:  1909  CROP  (Bushels  per  Acre) 


Corn  on  clover  sod;  land  cultivated  30  years,  with  no  manure  and  no 


pasture:  Untreated 


Same  kind  of  land:  Treated  with  |  ton  raw  rock  phosphate 
Same:  Treated  with  k  ton  phosphate  and  3  tons  limestone 

Second-year  corn  after  clover :  Untreated 

Same:  Treated  with  i  ton  per  acre  of  phosphate  .... 


65.1  bushels 
81.9  bushels 
84.1  bushels 

70.0  bushels 
77.6  bushels 


"  On  the  clover  sod  there  seems  to  be  about  a  normal  difference  in  yield. 
Much  of  the  last  field,  including  the  check  strip,  has  had  two  lo-ton  appli- 
cations of  manure  in  6  years. 

"  Kind  regards, 

(Signed)  "  F.  I.  MANN." 

"UNIVERSITY  OF  ILLINOIS,  URBANA,  December  i,  1909. 

"  MR.  F.  I.  MANN,  Oilman,  Illinois. 

"  DEAR  SIR  :  —  I  thank  you  for  your  letter  of  November  23,  giving  the 
1909  results  on  your  200  acres  of  corn  from  the  methods  of  soil  improvement 
which  you  have  been  practicing  for  several  years.  I  note  that  the  cumula- 
tive effect  of  the  system  is  apparently  becoming  evident.  Where  phosphorus 
produces  a  ton  more  clover  per  acre  (as  you  reported  last  year),  the  increased 
clover  and  added  phosphorus  must  increase  the  following  corn  crop. 

"Two  of  our  old  plots  here  at  the  University  yielded  exactly  the  same 
(64  bushels)  as  an  average  of  three  corn  crops  (1895-1897)  before  we  began 
applying  limestone  and  phosphorus  to  one  of  them.  This  year  the  untreated 
clover  sod  produced  32.8  bushels,  and  the  treated  land  yielded  77.6  bushels, 
per  acre.  Where  limestone  without  phosphorus  was  applied,  the  yield  was 
38  bushels,  and,  with  limestone,  phosphorus,  and  potassium,  83.7  bushels. 

"  Very  truly  yours, 

(Signed)  "  CYRIL  G.  HOPKINS." 


CHAPTER  XXV 

CANADIAN   FIELD   EXPERIMENTS 

THE  government  of  Canada  established  an  agricultural  experi- 
ment station  (Dominion  Experimental  Farms)  in  1886,  and  a  series 
of  field  experiments  were  begun  by  Director  Saunders  in  1887, 
which  have  been  continued  under  his  direction  for  more  than  20 
years. 

The  following  quotations  taken  from  the  Annual  Report  for 
1897  g've  general  information  concerning  these  experiments: 

"A  piece  of  sandy  loam,  more  or  less  mixed  with  clay,  which  was  originally 
covered  with  heavy  timber,  chiefly  white  pine,  was  chosen  for  these  tests.  The 
timber  was  cut  many  years  ago,  and  among  the  stumps  still  remaining  when 
the  land  was  purchased  there  had  sprung  up  a  thick  second  growth  of  trees, 
chiefly  poplar,  birch,  and  maple,  few  of  which  exceeded  six  inches  in  diameter 
at  the  base.  Early  in  1887  this  land  was  cleared  by  rooting  up  the  young  trees 
and  stumps  and  burning  them  in  piles  on  the  ground  from  which  they  were 
taken,  the  ashes  being  afterwards  distributed  over  the  soil  as  evenly  as  possible, 
and  the  land  plowed  and  thoroughly  harrowed.  Later  in  the  season  it  was 
again  plowed  and  harrowed,  and  most  of  it  got  into  fair  condition  for  cropping." 

"The  plots  laid  out  for  the  experimental  work  with  fertilizers  were  one  tenth 
of  an  acre  each,  21  of  which  were  devoted  to  experiments  with  wheat,  21  to 
barley,  21  to  oats,  21  to  Indian  corn  or  maize,  and  21  to  experiments  with  tur- 
nips and  mangels.  Owing  to  the  difficulty  and  unavoidable  delay  attending 
the  draining  of  some  wet  places,  it  was  not  practicable  to  undertake  work  on  all 
the  plots  the  first  season.  The  tests  were  begun  in  1888  with  20  plots  of  wheat 
and  1 6  of  Indian  corn;  and  in  1889  all  the  series  were  completed  excepting  six 
plots  of  roots,  Nos.  16  to  21  inclusive,  which  were  available  for  the  work  in  1890. 
In  all  cases  the  plots  in  each  series  have  been  sown  on  the  same  day." 

"In  1890  it  was  found  that  all  the  grain  plots  had  become  so  weedy  that  the 
growth  of  the  crops  was  much  interfered  with,  and  with  the  view  of  cleaning 
the  land,  one  half  of  each  of  the  wheat  and  oat  plots  was  sown  with  carrots  in 
1891,  and  one  half  of  each  of  the  barley  plots  with  sugar  beets.  In  1892  the 
other  half  of  each  plot  in  each  of  these  series  was  sown  with  carrots.  In  1893 
it  was  thought  desirable  to  continue  this  cleaning  process,  and  carrots  were  again 
sown,  on  the  half  of  the  wheat  and  oat  plots  occupied  with  this  crop  in  1891, 
and  also  on  the  half  of  the  barley  plots  cropped  with  sugar  beets  that  year.  In 

505 


506    INVESTIGATION    BY   CULTURE   EXPERIMENTS 

1894,  1895,  1896,  and  1897  the  one  half  of  the  oat  plots  were  sown  again  with 
carrots  and  the  half  of  the  plots  devoted  to  wheat  and  barley  were  planted  with 
potatoes." 

Other  changes  from  the  original  plans,  and  also  some  general 
conclusions  drawn  by  Doctor  Saunders  at  the  end  of  20  years,  are 
given  in  the  following  statements  quoted  from  the  Report  for  the 
year  ending  March  31,  1908. 

"These  trials  have  shown  that  barnyard  manure  can  be  most  economically 
used  in  the  fresh  or  unrotted  condition ;  that  fresh  manure  is  equal,  ton  for  ton, 
in  crop-producing  power  to  rotted  manure,  which,  other  experiments  have 
shown,  loses  during  the  process  of  rotting  about  60  per  cent  of  its  weight.  In 
view  of  the  vast  importance  of  making  the  best  possible  use  of  barnyard 
manure,  it  is  difficult  to  estimate  the  value  of  this  one  item  of  information. 

"When  these  experiments  were  planned,  the  opinion  was  very  generally  held 
that  untreated  mineral  phosphate,  if  very  finely  ground,  was  a  valuable  fertilizer, 
which  gradually  gave  up  its  phosphoric  acid  for  the  promotion  of  plant  growth. 
Ten  years'  experience  have  shown  that  mineral  phosphate,  untreated,  is  prac- 
tically of  no  value  as  a  fertilizer. 

"  Sulfate  of  iron,  which,  at  the  time  these  tests  were  begun,  was  highly  recom- 
mended as  a  means  of  producing  increased  crops,  has  also  proven  to  be  of  very 
little  value  for  this  purpose. 

"Common  salt,  which  has  long  had  a  reputation  with  many  farmers  for  its 
value  as  a  fertilizer  for  barley,  while  others  disbelieved  in  its  efficacy,  has  been 
shown  to  be  a  valuable  agent  for  producing  an  increased  crop  of  that  grain, 
while  it  is  of  much  less  use  when  applied  to  crops  of  spring  wheat  or  oats. 
Land-plaster  or  gypsum  has  also  proved  to  be  of  some  value  as  a  fertilizer  for 
barley,  while  of  very  little  service  for  wheat  or  oats.  Some  light  has  also  been 
thrown  on  the  relative  usefulness  of  single  and  combined  fertilizers. 

"After  ten  years'  experience  had  demonstrated  that  finely  ground,  untreated 
mineral  phosphate  was  of  no  value  as  a  fertilizer,  its  use  was  discontinued  in 
1898.  Prior  to  this  it  had  been  used  in  each  set  of  plots  in  Nos.  4,  5,  6,  7,  and  8, 
in  all  the  different  series  of  plots,  excepting  roots.  In  1898  and  1899,  similar 
weights  of  the  Thomas  phosphate  were  used  in  place  of  the  mineral  phosphate, 
excepting  in  plot  6  in  each  series.  In  this  plot  the  Thomas  phosphate  was  used 
in  1898  only. 

"After  constant  cropping  for  ten  or  eleven  years,  it  was  found  that  the  soil  on 
these  plots  to  which  no  barnyard  manure  had  been  applied  was  much  depleted 
of  humus,  and  hence  its  power  for  holding  moisture  had  been  lessened,  and  the 
conditions  for  plant  growth,  apart  from  the  question  of  plant  food,  had  on  this 
account  become  less  favorable.  In  1899  the  experiments  were  modified  and  an 
effort  made  to  restore  some  proportion  of  the  humus  and  at  the  same  time  gain 
further  information  as  to  the  value  of  clover  as  a  collector  of  plant  food.  In  the 
spring  of  that  year  ten  pounds  of  red  clover  seed  per  acre  was  sown  with  the 


CANADIAN   FIELD   EXPERIMENTS  507 

grain  on  all  the  plots  of  wheat,  barley,  and  oats.  The  young  clover  plants 
made  rapid  growth,  and  by  the  middle  of  October  there  was  a  thick  mat  of 
foliage  varying  in  height  and  density  on  the  different  plots,  which  was  plowed 
under.  No  barnyard  manure  was  applied  on  plots  i  and  2  in  each  series  from 
1898  to  1905. 

"In  1900  all  the  fertilizers  on  all  the  plots  were  discontinued,  and  from  then 
to  1905  the  same  crops  were  grown  on  all  these  plots  from  year  to  year  without 
fertilizers,  sowing  clover  with  the  grain  each  season.  In  this  way  some  infor- 
mation has  been  gained  as  to  the  value  of  clover  as  a  collector  of  plant  food,  and 
also  as  to  the  unexhausted  values  of  the  different  fertilizers  which  had  been  used 
on  these  plots  since  the  experiments  were  begun.  In  1905-6-7  all  the  fertilizers 
were  again  used  as  in  1898." 

The  corn  plots  and  root  plots  were  fertilized  somewhat  differ- 
ently from  the  others,  and  the  corn  was  cut  green  and  weighed  in 
the  fresh  condition.  The  results  with  wheat,  oats,  and  barley  are 
of  more  general  interest,  and  the  most  significant  data  from  these 
crops  are  recorded  in  Table  106,  in  which  all  dated  intervals  are 
inclusive. 

In  the  author's  opinion,  we  must  question  the  conclusion  of  Doc- 
tor Saunders  that  nonacidulated  mineral  phosphate  is  of  no  value 
as  a  fertilizer.  There  are  at  least  two  important  points  to  be  con- 
sidered before  drawing  any  final  conclusion :  First,  does  the  land 
need  phosphorus?  Or,  in  other  words,  is  phosphorus  the  limiting 
factor?  Sandy  loam  soils  are  more  likely  to  be  deficient  in  either 
nitrogen  or  potassium  than  in  phosphorus.1  Second,  was  any 
adequate  means  provided  in  the  system  of  farming  for  liberating 
the  phosphorus  from  the  raw  phosphate? 

From  Table  106  we  see  that  the  raw  phosphate  used  alone  pro- 
duced practically  no  increase  on  wheat,  oats,  or  barley,  but  this  is 
also  true  as  regards  fine-ground  bone  during  the  first  ten  years, 

1  Since  the  above  was  written,  Professor  Frank  T.  Shutt,  Chief  Chemist  of  the 
Dominion  Experimental  Farms,  has  kindly  furnished  the  author  unpublished 
analytical  data  from  samples  of  soil  collected  in  1898,  which  show  that  2  million 
pounds  of  surface  soil  contained,  for  plot  3  in  the  oats  series,  2130  pounds  of  nitro- 
gen, 1950  pounds  of  acid-soluble  phosphorus,  and  3160  pounds  of  acid-soluble 
potassium ;  while  the  corresponding  figures  for  plot  3  of  the  barley  series  were 
2600,  1850,  and  2990,  and  for  the  wheat  series,  2120,  1470,  and  3240  pounds. 
Compare  the  following  significant  figures: 

NITROGEN       PHOSPHORUS       POTASSIUM 

Oats 97oo  1600  6800 

Soil 2130  1950  3160 


508    INVESTIGATION   BY   CULTURE    EXPERIMENTS 


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Sodium  nitrate,  200  Ib.,  with  r 
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Rotting  manure,  6  tons,  with  r 
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Potassium  chlorid,  150  Ib.  . 
Ammonium  sulfate,  300  Ib.  . 

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CANADIAN   FIELD    EXPERIMENTS  509 

plot  13  yielding  only  1.2  bushels  more  wheat,  2.3  bushels  more 
oats,  and  .4  bushel  less  barley  than  plot  4.  The  300  pounds  of  cal- 
cium sulfate  on  plot  20  produced  .4  bushel  more  wheat,  the  same 
yield  of  oats,  and  .9  bushel  less  barley  than  the  500  pounds  of  acid 
phosphate  on  plot  21.  By  referring  to  Table  78,  we  find  that  as  an 
average  of  six  4-year  periods,  640  pounds  of  calcium  sulfate  pro- 
duced practically  no  effect  (12^  cents  per  acre  in  four  years),  while 
dissolved  bone  black  carrying  42  pounds  of  phosphorus  produced 
an  average  increase  of  $12.17.  These  results  certainly  indicate  that 
phosphorus  is  not  the  limiting  factor  in  crop  yields  on  the  Ottawa 
soil. 

The  effect  produced  on  oats  by  the  fine-ground  bone  is  probably 
due  to  the  nitrogen  contained  in  the  bone.  It  is  a  common  ob- 
servation that  oats  respond  to  nitrogen  more  rapidly  than  most 
other  crops  on  the  same  soil,  and  it  will  be  observed  that  sodium 
nitrate  alone  (plot  15)  produced  practically  the  same  effect  on 
oats  as  the  nitrate  and  acid  phosphate  combined.  Where  nitrogen 
was  provided,  the  raw  phosphate  (plots  5  and  7)  produced  a  larger 
average  increase  on  oats  than  did  the  acid  phosphate  (plots  10 
and  u),  during  the  first  nine  years. 

A  study  of  the  results  with  wheat  and  barley  indicate  that  potas- 
sium is  the  first  limiting  element  for  those  crops.  As  an  average  of 
the  first  ten  years,  the  largest  yield  of  wheat  was  produced  by  po- 
tassium chlorid,  aside  from  the  farm-manure  plots;  and  the  second 
largest  yield  was  with  ashes  (plot  14;  compare  with  13).  Sodium 
chlorid  also  produced  some  increase  in  the  yield  of  wheat,  and  with 
barley  the  300  pounds  of  sodium  chlorid  produced  the  largest  yield, 
aside  from  the  two  heavily  manured  plots.  Even  acid  phosphate, 
containing  much  calcium  sulfate  and  an  acid  salt  of  phosphorus, 
may  liberate  some  potassium.  It  may  be  questioned  whether  potas- 
sium or  nitrogen  is  most  limiting  for  the  barley  crop,  but  it  is  plain 
that  phosphorus  is  not  the  limiting  element.  Even  during  the  sec- 
ond ten  years,  the  150  pounds  of  potassium  chlorid  or  the  300 
pounds  of  sodium  chlorid  rank  higher  than  500  pounds  of  bone 
or  500  pounds  of  acid  phosphate,  in  either  trial  (plots  9  and  21), 
and  also  far  above  the  slag  phosphate  (plot  4) . 

On  plot  6  the  raw  phosphate  was  applied  in  connection  with 
"  actively  fermenting  "  manure,  and  it  may  have  produced  some 


5io    INVESTIGATION   BY   CULTURE   EXPERIMENTS 

effect,  but  this  cannot  be  known,  because  there  is  no  comparison 
plot  on  which  the  same  amount  of  untreated  manure  was  used. 
If  we  average  plots  i  and  2,  we  find  that  6  tons  of  phosphated 
manure  on  plot  6  produced  more  than  70  per  cent  as  much  in- 
crease as  15  tons  on  plots  i  and  2.  Comparison  with  the  Penn- 
sylvania and  Ohio  experiments  does  not  help  much  in  trying  to 
decide  if  the  raw  phosphate  was  effective  when  mixed  with  the 
manure  at  Ottawa,  in  part  because  the  applications  are  propor- 
tionately different,  and  in  part  because  the  manure  itself  produces 
different  effects  on  different  soils.  With  the  data  presented,  any 
possible  comparisons  can  be  made  by  the  student. 

Except  for  the  oat  crops  which,  as  stated,  usually  respond  readily 
to  nitrogen,  ammonium  sulfate  with  the  60  pounds  of  nitrogen 
produced  a  smaller  average  effect  than  the  sodium  nitrate  with 
30  pounds  of  nitrogen,  thus  indicating  that  the  sodium  in  the 
nitrate  exerted  appreciable  influence. 

Apparently,  iron  sulfate  produced  some  small  effect,  but  it  is 
doubtful  if  it  is  greater  than  would  have  been  produced  by  60 
pounds  of  sodium  chlorid.  For  this  and  other  comparisons  in- 
volving few  plots,  the  author  calls  attention  to  the  fact  that  there 
are  some  marked  natural  variations  among  the  individual  plots  in 
these  series;  and  in  such  cases  no  final  conclusions  can  be  drawn. 
In  the  oat  series,  plot  3  produced  9  bushels  more  oats  per  acre  than 
plot  12  as  an  average  for  the  first  nine  years,  and  14  bushels  more 
for  the  next  ten  years.  Plot  n  in  the  oat  series  is  evidently  a 
plot  which  yields  below  normal. 

The  quotations  from  Doctor  Saunders  show  that  some 
parts  of  the  field  were  naturally  wetter  than  others,  and  on 
page  51  of  the  Annual  Report  for  1897  the  statement  is  made 
that  "  plots  12,  13,  and  14  were  on  a  piece  of  rising  ground  on 
light  soil." 

The  records  for  1903  and  1904  give  the  yields  for  the  last  two 
years  of  green  manuring  with  catch  crops  of  clover,  while  1906 
and  1907  furnish  later  records  after  the  fertilizer  applications 
were  renewed,  beginning  with  1905. 

In  Table  107  are  given  probably  the  most  significant  data  from 
the  root  crops  (and  potatoes)  that  were  grown  on  alternating 
half  plots  in  these  series  during  the  seven  years,  1891  to  1897. 


CANADIAN    FIELD    EXPERIMENTS 


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512     INVESTIGATION   BY    CULTURE   EXPERIMENTS 

These  results  may  serve  as  a  control  or  check  when  comparisons 
are  needed.1 

Thus,  from  Table  106,  we  note  that  iron  sulfate  produced  a 
more  marked  effect  upon  oats  and  barley  than  upon  wheat;  but 
in  Table  107  we  observe  that,  as  a  three-year  average,  iron  sulfate 
decreased  the  yield  of  carrots  on  the  wheat  series,  and  increased 
markedly  the  carrot  crop  when  grown  on  the  oat  series.  Likewise, 
with  potatoes,  iron  sulfate  decreased  the  yield  by  8  or  28  bushels 
on  the  wheat  land,  and  produced  an  increase  of  8  bushels  or  a 
decrease  of  13  bushels  on  the  barley  series.  All  of  this  means  that 
apparent  results  from  treatment  not  controlled  by  some  sort  of 
repetition  are  not  to  be  given  great  confidence,  especially  when 
the  apparent  effect  of  the  treatment  is  no  greater  than  the  difference 
between  the  untreated  plots,  or  between  any  two  plots  which  are 
fairly  comparable,  as  plots  5  and  10,  wherever  plot  5  shows  the 
larger  yield. 

1  Evidently  through  a  clerical  error,  the  three-year  average  yield  of  carrots  from 
the  wheat  series  was  credited  to  the  oats  series  in  the  1894  Report  of  the  Dominion 
Experimental  Farms,  and  this  error  was  continued  in  the  subsequent  reports; 
consequently  the  above  corrected  seven-year  average  does  not  agree  with  the  data 
given  in  the  1897  Report. 


CHAPTER  XXVI 


SHORT-TIME     POT-CULTURE    AND     WATER-CULTURE     EXPERI- 
MENTS   IN    COMPARISON    WITH    FIELD    RESULTS 

THE  United  States  Bureau  of  Soils  has  developed  methods  of 
making  culture  experiments  in  paraffined  wire  pots  and  in  water 
extracts  of  soils,  which  it  was  hoped  would  furnish  information  from 
two  or  three  weeks'  growth  of  seedling  plants  that  would  serve  as 
a  useful  guide  in  determining  the  fertilizer  requirements  of  the  soil. 

TABLE  108.   EXPERIMENTS  ON  WOOSTER  (OHIO)  SOIL 

Comparison  of  Ohio  Field  Experiments  with  Bureau  of  Soils'  Pot  Cultures  for 

determining  Needed  Elements  of  Plant  Food 

(a)   OHIO  STATION'S  NINE  YEARS'  TEST  IN  FIELD 
Average  Increase  in  Yield  per  Acre 


EFFECT  PRODUCED  BY  : 

CORN 
(Bu.) 

OATS 
(Bu.) 

WHEAT 
(Bu.) 

HAY1 

(Lb.) 

Nitrogen  (NP  over  P)     

6.=U 

6  ?2 

4.17 

881 

Phosphorus  (alone)     

6.  so 

7.46 

6.96 

40O 

Potassium  (KP  over  P)  

4.  1  1 

2.2.4 

2.O2 

222 

Nitrogen  (NPK  over  PK)   .... 

4.48 

8.18 

5-44 

737 

Phosphorus  (PNK  over  NK)  .     .     . 

11.05 

I4-52 

12.45 

1077 

Potassium  (KNP  over  NP)      .     .     . 

2.06 

4  oo 

3-29 

289 

(b)   BUREAU  OF  SOILS'  TWENTY-DAY  TEST  IN  POTS 
Weight  of  Green  Tops  (Increase  only,  in  Grams) 


EFFECT  PRODUCED  BY  : 

ORDINARY 
SOIL 

WITH 
LIME 

WITH 
MANURE 

WITH  LIME 

AND 

MANURE 

Nitrogen  (NP  over  P)     

2.71 

4.20 

1.90 

2.50 

Phosphorus  (alone)     

—  .OI 

.IO 

—  .70 

—  1.  2O 

Potassium  (KP  over  P)       .... 

.81 

.^O 

.OO 

—  .30 

Nitrogen  (NPK  over  PK)   .... 

2.8o 

2.6o 

2.90 

-2.80 

Phosphorus  (PNK  over  NK)  .     .     . 

•95 

—  .IO 

-.40 

-4.80 

Potassium  (KNP  over  NP)      .     .     . 

.90 

—  I.IO 

I.OO 

-5.60 

N  =  nitrogen;  P  =  phosphorus;   K  =  potassium. 

1  Increase  in  clover  and  timothy  hay. 

5*3 


514    INVESTIGATION   BY   CULTURE   EXPERIMENTS 


TABLE  109.   EXPERIMENTS  ON  WOOSTER  (Omo)  SOIL 
(a)   STATEMENT  SHOWING  ACTUAL  INCREASE  AND  ORDER  OF  EFFECTIVENESS 


PLOT 
No. 

TREATMENT 

OHIO  STATION'S  9 
YEARS'  FIELD  TEST 
WITH  WHEAT  ;  Av. 
Bu.  PER  ACRE 
(Increase  Only) 

BUREAU  OF  SOILS' 
SOIL  EXTRACT  CUL- 
TURES ;  WATER  TRANS- 
PIRED BY  WHEAT 
SEEDLINGS 
(Increase  Only) 

Bushels 

Order 

Grams 

Order 

e 

Nitrogen     

1.  4.1 

I 

216 

4 

o 

Potassium  '   . 

A'T- 

1.48 

2 

—  4 

•t 
I 

9 

Nitrogen,  potassium     .... 

*  •*rw 

1.97 

3 

24I 

5 

2 

Phosphorus     

6.96 

A 

78 

2 

8 

Phosphorus,  potassium      .     .     . 

8.98 

*T 

5 

/ 
121 

3 

6 

Nitrogen,  phosphorus  .... 

11.13 

6 

268 

6 

ii 

Nitrogen,  phosphorus,  potassium 

14.42 

7 

279 

7 

COMPARISON  OF  OHIO  FIELD  EXPERIMENTS  WITH  BUREAU  OF  SOILS, 
WATER  CULTURES  FOR  DETERMINING  NEEDED 
ELEMENTS  OF  PLANT  FOOD 


EFFECT  PRODUCED  BY  : 

OHIO  WHEAT  YIELDS 
IN  FIELD  TESTS,  AV- 
ERAGE OF  9  YEARS, 
BUSHELS  PER  ACRE 
(Increase  Only) 

BUREAU  OF  SOILS' 
EXTRACT  CULTURES, 
WATER  TRANSPIRED 
BY  WHEAT  SEEDLINGS 
(Increase,  Grams) 

Nitrogen  (NK  over  K)    

.40 

24? 

Nitrogen  (alone)     

I  41 

216 

Nitrogen  (NP  over  P)     

4  17 

IOO 

Nitrogen  (NPK  over  PK)    

C   A  A 

i<;8 

Phosphorus  (PK  over  K)     

7  Co 

12"? 

Phosphorus  (alone)     

696 

78 

Phosphorus  (PN  over  N)     

Q.72 

C2 

Phosphorus  (PNK  over  NK)   .... 

12.45 

38 

Potassium  (KP  over  P)  •  

2  O2 

A\ 

Potassium  (KN  over  N)       

.56 

2< 

Potassium  (KNP  over  NP)      .... 
Potassium  (alone)  

3-29 

I  48 

ii 
—4 

Tables  108  and  109  show  the  results  of  such  culture  experiments 
in  direct  comparison  with  the  average  results  of  nine  years'  field 
experiments  by  the  Ohio  Agricultural  Experiment  Station  on  the 


POT   CULTURES   VERSUS   FIELD   EXPERIMENTS    515 

same  type  of  soil  at  Wooster.  In  one  experiment  the  Bureau's 
results  are  reported  in  terms  of  "  weight  of  green  tops  "  of  the 
wheat  seedlings,  and  in  the  other  in  terms  of  water  transpired  by 
the  young  plants,  which  Whitney  and  Cameron  have  held  to  be  a 
satisfactory  measure  of  plant  growth. 

It  will  be  noted  that  the  disagreement  between  the  2o-day  tests 
of  the  Bureau  and  the  nine  years'  field  results  of  the  Ohio  Station 
is  so  nearly  perfect  as  to  render  the  short-time  culture  experiments 
of  no  value.  (See  Ohio  Experiment  Station  Bulletin  167  and  Illi- 
nois Experiment  Station  Circulars  105  and  123.) 

The  author  has  repeatedly  emphasized  the  fact  that  the  student 
of  soil  fertility  should  study  the  data  secured  in  soil  investigations, 
and  thus  be  prepared  to  draw  his  own  conclusions.  The  importance 
of  this  is  well  illustrated  by  the  following  statement  from  the 
Bureau  of  Soils  concerning  the  data  under  discussion: 

"  The  general  conclusions  from  the  field  experiments,  both  in  the  begin- 
ning in  1894  and  in  their  more  advanced  stages,  are  in  agreement  with  those 
carried  on  by  the  methods  of  basket  cultures  and  cultures  in  soil  extract." 
(See  page  116,  Ohio  Bulletin  167,  written  by  the  Bureau  of  Soils.) 

In  his  introduction  to  Ohio  Bulletin  168  (page  122),  Professor 
Milton  Whitney,  as  Chief  of  the  United  States  Bureau  of  Soils, 
makes  the  following  statement: 

"The  results  of  the  two  investigations  at  Wooster  and  Strongsville  leave  no 
reasonable  doubt  that  the  paraffin  pot  method  does  give  results  in  harmony 
with  the  average  results  obtained  by  the  much  longer  timed  experiments  in  the 
field.  It  thus  has  an  unquestionable  value  as  a  practical  method  for  investigat- 
ing the  manurial  requirements  of  the  soil." 

Attention  is  called  to  the  fact  that  the  form  of  statement  used 
in  Table  109  is  not  only  entirely  fair  and  trustworthy,  but  it  is 
the  only  method  by  which  the  effect  produced  by  each  element 
can  be  ascertained  for  the  different  conditions.  Suppose,  for  ex- 
ample, that  a  farmer  is  using  potassium  alone  upon  his  land  for 
increasing  his  crop  yields  (which,  as  a  matter  of  fact,  hundreds 
of  Illinois  farmers  are  doing  on  peaty  swamp  lands).  The  ques- 
tion may  naturally  arise,  Will  it  pay  to  apply  nitrogen  also  to  the 
soil  ?  According  to  the  Bureau's  results,  such  an  addition  to  this 
Ohio  soil  would  produce  a  greater  increase  than  any  other  addition 
of  a  single  element ;  while,  according  to  nine  years'  actual  field 


5i6    INVESTIGATION   BY   CULTURE    EXPERIMENTS 

trials  by  the  Ohio  Station,  such  an  addition  produces  a  smaller 
increase  than  any  other. 

Again,  suppose  the  farmer  is  adding  nitrogen  to  his  «soil,  as 
most  farmers  are  doing  by  growing  legumes,  if  not  in  commercial 
form.  There  is  no  more  sensible  or  appropriate  question  than, 
Will  it  pay  to  add  phosphorus  also?  The  Ohio  Station  reports 
that  such  an  addition  of  phosphorus  will  increase  the  yield  of 
wheat  9.72  bushels  per  acre  annually,  which  is  almost  seven  times 
the  increase  produced  by  nitrogen  alone ;  but  according  to  the 
tests  by  the  Bureau  of  Soils  the  increase  of  phosphorus  added  in 
this  way  would  be  less  than  one  fourth  of  that  produced  by  the 
nitrogen. 

So  far  as  nitrogen  and  phosphorus  are  concerned,  the  perfect 
disagreement  between  the  water-culture  method  and  the  actual 
field  results  is  indeed  remarkable. 

The  addition  of  potassium  produces  some  increases  in  the  field 
experiments,  but  they  are  not  in  accordance  with  the  results 
obtained  with  the  soil-extract  cultures,  the  lowest  positive  increase 
by  potassium  in  the  water  cultures  being  produced  where  its  effect 
should  have  been  greatest,  as,  indeed,  was  the  case  in  the  field 
trials;  namely,  when  applied  in  addition  to  both  phosphorus  and 
nitrogen. 


EDWARD  B.  VOURHEES,  DIRECTOR  OF  NEW  JERSEY 
AGRICULTURAL  EXPERIMENT  STATION 

Author  of  "  Fertilizers  " 


PART    IV 
VARIOUS    FERTILITY   FACTORS 

CHAPTER  XXVII 

MANUFACTURED    COMMERCIAL    FERTILIZERS 

THE  three  elements,  nitrogen,  phosphorus,  and  potassium,  in 
so-called  available  forms,  have  become  important  articles  of  com- 
merce. In  Europe  they  are  usually  purchased  singly  and  applied 
with  reference  to  the  deficiencies  of  the  soil  and  the  needs  of 
the  crop;  but  in  America  the  commercial  fertilizer  business  has 
been  developed  largely  in  the  line  of  mixed  goods,  or  so-called 
complete  fertilizers,  which  are,  in  fact,  known  and  purchased  by 
name  much  more  generally  than  upon  any  clear  understanding 
of  their  composition  with  respect  to  the  needs  of  the  soil  and  crop. 
This  is  very  largely  the  fault  of  the  American  statesman,  who, 
as  Hunter  said  of  the  French  Minister,  Colbert,  "gave  all  possible 
encouragement  to  the  artisan  and  the  merchant,  but  forgot  that 
the  manufacturer  must  eat  his  bread  at  a  moderate  price."  Thus 
for  a  hundred  years  after  most  of  the  agricultural  lands  between 
Washington  and  Richmond  had  been  abandoned  for  agricultural 
purposes,  the  American  statesman  gave  no  apparent  thought  to 
the  development  of  permanent  systems  of  agriculture. 

No  wiser  use  could  be  made  of  public  money  than  for  the  Rep- 
resentatives in  Congress  to  secure  for  the  agricultural  experi- 
ment stations  of  each  state  federal 1  appropriations  of  say  $5000 
for  each  congressional  district  in  the  state,  to  be  used  solely  for 

1 1n  this  connection  it  is  well  to  remember  that  even  relatively  the  state  rev- 
enues are  very  meager  compared  with  those  of  the  federal  government.  Thus, 
Illinois'  "share"  of  the  federal  revenues  is  approximately  ten  times  the  total 
revenue  of  the  Illinois  state  government.  The  soil  is  the  principal  source  of  all 
revenue,  either  direct  or  indirect. 


5i8  VARIOUS   FERTILITY   FACTORS 

the  investigation  of  the  soils  of  the  state  with  a  view  to  the  ulti- 
mate adoption  of  permanent  systems  of  profitable  agriculture  on 
every  type  of  soil  in  every  state. 

The  first  important  movement  tending  in  this  direction  by 
the  national  government  is  represented  in  "  AN  ACT  donating 
Public  Lands  to  the  several  States  and  Territories  which  may 
provide  Colleges  for  the  benefit  of  Agriculture  and  the  Mechanic 
Arts,"  which  was  signed  by  President  Lincoln  on  July  2,  1862. 
This,  the  first  "Morrill  Bill,"  was  an  endowment  for  instruction  only; 
and  it  was  not  until  March  2,  1887,  that  the  "  Hatch  Act  "  became 
a  law,  "  AN  ACT  to  establish  Agricultural  Experiment  Stations  in 
connection  with  the  Colleges  established  in  the  several  States  under 
the  provisions  of  an  act  approved  July  2,  1862." 

Thus,  the  experiment  station,  which  is  the  chief  source  of  correct 
agricultural  information,  was  established  twenty-five  years  later 
than  the  agricultural  college,  with  the  result  that  for  twenty-five 
years  and  more  the  state  agricultural  college  was  required  to  teach, 
without  facts  or  knowledge  concerning  the  agriculture  of  the  state.1 
Under  these  conditions  it  is  not  so  strange  that  the  practice  of  the 
American  farmer  with  respect  to  the  use  of  commerical  fertilizers 
has  been  essentially  a  continuation  of  his  previous  system  of  soil 
depletion,  the  fertilizer  being  used  almost  invariably  as  a  soil  and 
crop  stimulant,  which  leaves  the  soil  poorer  and  poorer  with 
continued  use. 

The  following  bona  fide  examples  are  fair  illustrations  of  the 
"  complete  "  commercial  fertilizers  now  being  used  in  the  United 
States  to  the  extent  of  more  than  $100,000,000  annually. 

"HOMESTEAD  TOBACCO  GROWER 

"  Guaranteed  Analysis 

Available  phosphoric  acid       10.00  to  11.00% 

Equal  to  available  bone  phosphate 21.00  to  24.00% 

Soluble  phosphoric  acid 8.00   to  9.00% 

Equal  to  soluble  bone  phosphate 17.00  to  19.00% 

Insoluble  phosphoric  acid 50   to  1.50% 

1  In  1900,  when  it  became  the  author's  duty  to  teach  the  subject  of  soil  fertility 
to  Illinois  students,  there  was  no  source  of  knowledge  concerning  the  composition 
of  Illinois  soils. 


MANUFACTURED    COMMERCIAL   FERTILIZERS     519 

Equal  to  insoluble  bone  phosphate i.oo  to  3.25% 

Nitrogen,  total  available 3.00  to  4.00% 

Equal  to  total  available  ammonia 3.50  to  4.75% 

Potash  (KaO) 3.50  to  4.00% 

As  potash  sulfate 6.50  to  7.50% 

"Our  HOMESTEAD  TOBACCO  GROWER  is  well  known,  especially  in  the  to- 
bacco-growing districts  of  Kentucky,  Tennessee,  and  southern  Ohio,  and  the 
excellent  results  given  make  it  needless  for  us  to  add  our  own  recommenda- 
tion of  it.  For  producing  the  best  quality  of  tobacco  it  is  unexcelled." 


"COMPLETE  MANURED 

"  Guaranteed  Analysis 

PER  CENT 

Total  phosphoric  acid 8.00  to  n  oo 

Available  phosphoric  acid 7.00  to  10.00 

Equal  to  available  bone  phosphate 15.25   to  21.85 

Nitrogen        82   to  1.65 

Ammonia i.oo  to  2  oo 

Potash  (K2O) i.oo  to  2.00 

"This  brand  is  what  its  name  implies  —  a  complete  manure  for  general  use, 
in  good  mechanical  condition,  containing  all  the  different  elements  in  propor- 
tions. In  fact,  it  is  a  well-balanced  fertilizer,  and  the  demand  for  it  has  been 
large  and  is  growing  each  year." 


"WESTERN  BRAND 

"  Guaranteed  Analysis 

PER  CENT 

Nitrogen 41  to       .82 

Ammonia \  to  i 

Available  phosphoric  acid 7  to  9 

Equal  bone  phosphate 15  to  19 

Total  phosphoric  acid 9  to  10 

Potash  sulfate .9  to  if 

Potash  (K2O) |  to  i 

"We  put  this  brand  on  the  market  to  satisfy  a  call  for  a  low-priced  fertilizer. 
By  looking  up  the  matter  you  will  find  that  most  low-priced  goods  give  you  no 
ammonia  at  all,  and  some  no  potash,  while  we  give  you  quite  a  liberal  amount 
of  both,  which  makes  this  brand  worth  more  to  you  than  any  low-priced  article 
on  the  market." 

1  This  was  retailed  at  country  stations  at  $26  a  ton.  —  C.  G.  H. 


520  VARIOUS    FERTILITY   FACTORS 

"YORK  STATE  SPECIAL 
"  Guaranteed  Analysis 

PER  CENT 

Nitrogen 82  to    1.65 

Ammonia i       to    2 

Available  phosphoric  acid 8       to  10 

Total  phosphoric  acid 10       to  12 

Potash,  actual  K2O 4       to    5 

"A  high-grade  complete  fertilizer  especially  prepared  for  general  farm  and 
garden  purposes.  A  good  sugar-beet  fertilizer.  Can  be  used  under  fruits, 
tobacco,  grain,  truck,  and  all  agricultural  products." 

"WHEAT,  CORN,  AND  OAT  SPECIAL  1 

"Guaranteed  Analysis 

PER  CENT 

Nitrogen 82  to   1.65 

Ammonia i  to    2 

Total  phosphoric  acid 9  to  n 

Available  phosphoric  acid 7  to    9 

Potash,  actual  KaO i  to     2 

"  For  wheat  and  cereals  generally.     Apply  from  200  to  400  pounds  per  acre." 
"EAGLE  WHEAT  AND  CORN  GROWER2 

PER  CENT 

Ammonia 2  to     3 

Potash,  actual 2  to     3 

Available  phosphoric  acid 8  to  10 

Total  phosphoric  acid 10  to  12 

"This  goods  meets  the  wants  for  a  high-grade  fertilizer  for  all  grain  crops, 
and  is  especially  recommended  for  grass  and  clover,  on  account  of  the  bone 
tankage  used  to  make  up  the  formula.  Take  no  substitute  for  this  well-known 
brand,  but  insist  on  GLOBE  EAGLE." 

The  above  quotations  are  from  various  fertilizer  companies  in 
different  parts  of  the  United  States.  The  guaranteed  analyses 
are  almost  invariably  correct,  but,  of  course,  the  guarantee  applies 
only  to  the  minimum  percentage  specified.  The  statement  of 
composition  is  sometimes  so  complicated  that  it  requires  a  chemist 
to  understand  it.  For  example,  the  author  has  received  a  com- 

1  Sold  locally  for  $22  and  at  $22.50  per  ton,  at  different  points.  —  C.  G.  H. 
3  Sold  locally  for  $25  per  ton.  —  C.  G.  H. 


MANUFACTURED    COMMERCIAL   FERTILIZERS     521 


munication  from  a  landowner  of  classical  education,  calling  atten- 
tion to  the  fact  that  a  certain  "  guaranteed  analysis  "  showed 
more  than  100  per  cent  by  adding  together  the  percentages  of  all 
ingredients.  This  would  be  true  of  the  "  Homestead  tobacco 
grower"  if  the  statement  included  "Total  phosphoric  acid  "  and 
"  Equal  to  total  bone  phosphate,"  which  are  often  reported. 
The  simplified  statement  would  be  as  follows: 

HOMESTEAD  TOBACCO  GROWER 
Guaranteed  Analysis 


PER  CENT 

POUNDS  PER  TON 

Available  nitrogen                    

3.O 

00 

Potassium  (in  sulfate)        

2.Q 

c8 

Available  phosphorus             I     

4.2 

84 

Insoluble  phosphorus    

.2 

4 

The  following  statement  shows  the  complete  line  of  fertilizers  sold 
by  one  of  the  large  packing-house  companies  of  Chicago,  and  the 
quotations  also  show  a  hopeful  tendency  toward  educational  effort 
on  the  part  of  some  manufacturers. 

"  —  — 's  FERTILIZERS 

Brands  and  Analyses 

"  Maximum  guaranteed  analyses  are  misleading  —  our  guaranteed  analyses 
in  table  below  are  minimum. 


BRAND 

NITRO- 
GEN 
(N) 

AMMO- 
NIA 

(NHS) 

PHOSPHORIC  ACID 
(PS06) 

POTASH 
(K,0) 

Available 

Total 

3-75 
3-75 
3-75 
2.50 
0.82 
5.00 

4-75 
2.50 
1.64 
1.64 

4-5° 
4-50 
4-50 
3.00 

1.  00 

6.00 

5-75 
3.00 

2.OO 
2.OO 

23.00' 
23.00' 
23.00' 
25.00' 
27.50' 
17.00' 

16.00' 

23-5°' 
13.00' 
13.00' 

Bone  meal 

Ammoniated  bone  and  potash    .     .     . 
Bone  and  potash 

3.00 
3.00 

2.00 
2.OO 

Soluble  bone  and  potash    

I2.0O1 
I2.001 

Champion  wheat  and  corn  grower  . 

1  Phosphoric  acid  derived  entirely  from  bone. 


522 


VARIOUS   FERTILITY   FACTORS 


*s  FERTILIZERS — Continued 


Brands  and  Analyses 

"  Maximum  guaranteed  analyses  are  misleading  —  our  guaranteed  analyses 
in  table  below  are  minimum. 


BKARD 

NITRO- 
GEN 
(N) 

AMMO- 
NIA 
(NH»> 

PHOSPHORIC  Aero 
(P.OS) 

POTASH 
(K,0> 

Available 

Total 

"Superphosphate      ....... 

1.64 
1.  00 

2.50 
.82 

1.64 
1.64 

2.47 

2-47 
1.64 

2.00 
1.25 

3-oo 

1.  00 
2.OO 
2.0O 
3.00 

3-oo 

2.OO 

8.00 
8.00 

8.00 
8.00 
8.00 

IO.OO 
IO.OO 

8.00 

IO.OO 
IO.OO 

14.00 

IO.OO 

12.00 
11.00 
II.OO 
10.00 
II.OO 

13.00 
13.00 

IO.OO 
II.OO 
II.OO 

15.00 

II.OO 

2.OO 
I.OO 

5.00 

4.00 
7.00 

2.OO 

3-0° 

IO.OO 

1  Complete  fertilizer      

1  Sugar-beet  grower  , 

1  Truck  grower     

1  Onion,  potato,  and  tobacco       .     .     . 
1  Kentucky  tobacco  grower    .... 
1  Special  tobacco  fertilizer      .... 
1  Vegetable  and  tobacco  grower  .     .     . 
Ammoniated  phosphate     
Special  phosphorus  and  potash  .     .     . 
O&rdcn  city  phosphate 

2.OO 
n 

Diamond  "S"  phosphate       .... 

1  Insoluble  phosphoric  acid  derived  from  animal  bone. 


"Nitrogen  (ammonia)  in  all  the  above  brands  derived  from  Blood  and  Bone. 

"  Purchasers  of  fertilizers  should  profit  by  the  fact  that  the  higher  the  guaran- 
teed fertilizer  analysis,  the  less  the  cost  of  the  plant  food  obtained,  allowing  for 
equal  distances  of  shipment.  It  pays,  therefore,  to  buy  fertilizers  on  the  basis 
of  analyses  and  not  simply  by  the  price  per  ton  for  some  certain  brand.  By 

making  a  careful  comparison  of  our  analyses  when  buying  fertilizers, 's 

will  lead. 

"For  the  convenience  of  our  customers  in  making  comparisons  of  values  of 
different  fertilizers,  we  suggest  the  following  as  being  approximate  values: 

"  (i)  Pure  Bone  Fertilizers.  If  any  one  of  these  grades  is  desired,  the  values 
for  the  essential  compound  ingredients  may  be  limited  as  follows: 

Ammonia  at  15  c.  per  Ib. $3.00  per  unit 

Phosphoric  acid  at  5  c.  per  !b i.oo  per  unit 

Potash,  actual,  at  6c.  per  Ib 1.20  per  unit 

Ammonia  at  15  c.  per  Ib 3.00  per  unit 

"(2)  Acidulated  Fertilizers,  which  are  more  complex  in  their  nature  and 
manufacture,  may  be  judged  comparatively  by  the  following: 


MANUFACTURED    COMMERCIAL   FERTILIZERS    523 

Phosphoric  acid,  available,  at  7  c.  per  lb $1.40  per  unit 

Phosphoric  acid,  insoluble  from  bone,  at  5  c.  per  Ib i.oo  per  unit 

Phosphoric  acid,  insoluble  from  rock,  at  i  c.  per  lb 20  per  unit 

Potash,  actual,  at  6c.  per  lb 1.20  per  unit 

"Multiplying  the  minimum  guarantees  with  the  above  valuations  per  unit,  the 
total  is  the  relative  value  per  ton  of  2000  pounds." 

Of  these  fertilizers,  the  "Special  Bone  Meal,"  containing  12  per 
cent  of  phosphorus,  is  a  fair  grade  of  steamed  bone  meal,  and  the 
"Garden  City  Phosphate"  containing  6.1  per  cent  of  available 
phosphorus  and  less  than  £  per  cent  of  insoluble  phosphorus 
represents  the  most  common  grade  of  acid  phosphate  on  the  mar- 
ket. At  the  prices  given,  a  pound  of  phosphorus  would  cost  about 
1 1  cents  in  steamed  bone  meal  and  about  16  cents  in  acid  phosphate. 

In  some  cases  different  brands  have  the  same  composition,  even 
where  sold  by  the  same  company.  In  fact,  some  of  the  larger 
fertilizer  companies  sell  a  dozen  different  brands  of  the  same  com- 
position, so  that  the  total  number  of  brands  sold  by  all  companies 
is  very  large,  amounting  to  about  goo  in  the  state  of  Indiana  and 
to  more  than  1800  in  Georgia,  which  only  emphasizes  the  fact  that 
most  farmers  purchase  fertilizers  by  name  rather  than  on  the  basis 
of  plant  food.  Probably  half  of  all  the  fertilizers  bought  by 
American  farmers  have  as  an  average  the  "  2-8-2  formula,"  as 
in  the  "  Superphosphate  "  and  "  Eagle  Wheat  and  Corn  Grower." 

In  some  states,  as  in  Illinois,  a  deficiency  of  i  per  cent  below  the 
miminum  guarantee  is  "  not  considered  evidence  of  fraudulent 
intent,"  but  greater  deficiencies  subject  the  dealer  to  a  severe  pen- 
alty if  prosecuted.  (See  Model  Fertilizer  Law,  in  the  Appendix.) 
In  most  states  the  burden  of  "  fertilizer  inspection  and  control  " 
is  placed  upon  the  agricultural  experiment  station,  and  some- 
times this  burden  has  almost  prevented  the  stations  from  con- 
ducting investigations  concerning  the  soils  of  the  state  or  in  other 
important  lines  where  exact  information  is  needed.  In  other  states, 
as  in  Pennsylvania,  Ohio,  and  Illinois,  the  enforcement  of  fertilizer 
laws  is  placed  with  the  State  Board  of  Agriculture,  and  the  ex- 
periment station  is  left  free  to  conduct  agricultural  experiments 
and  investigations.  It  may  be  added  that  there  is  grave  doubt  if 
the  agricultural  investigator  should  be  compelled  to  depend,  either 
in  large  part  or  in  small  part,  upon  the  income  from  tonnage  tax 


524  VARIOUS   FERTILITY   FACTORS 

or  brand  tax  of  commercial  fertilizers  sold  in  his  state,  as  a  source 
of  revenue  for  the  support  of  his  department  of  investigation. 

FORMS  AND  SOURCES  OF  COMMERCIAL  NITROGEN 

Aside  from  the  free  nitrogen  of  the  air,,  there  are  four  distinct 
"  forms  "  of  nitrogen :  (i)  organic  nitrogen,  (2)  ammonia  nitrogen, 
(3)  nitrate  nitrogen,  and  (4)  cyanamid  nitrogen. 

Aside  from  farm  manure  and  crop  residues,  the  chief  sources  of 
organic  nitrogen  are  (i)  dried  blood  and  tankage  from  the  slaughter 
houses  or  stock  yards,  (2)  cotton-seed  meal  from  the  oil  refineries 
in  the  South,  and  (3)  fish-scrap  in  the  Eastern  and  extreme  West- 
ern states.  (Near  the  coast  seaweed  often  becomes  the  staple 
manure.  It  contains  about  as  much  nitrogen  and  phosphorus  as 
farm  manure,  and  nearly  five  times  as  much  potassium.) 

Dried  blood.  A  good  grade  of  dried  blood  contains  14  per  cent 
of  nitrogen,  while  tankage  is  of  various  grades,  ranging  almost 
from  blood  to  bone.  It  contains  much  of  the  offal,  and  may  include 
the  undigested  contents  of  the  stomach  and  intestinal  tract. 
One  common  grade  is  "7  and  30"  tankage,  meaning  7  per  cent 
of  ammonia  (NH3)  and  30  per  cent  of  "  bone  phosphate,"  Ca3(PO4)2, 
corresponding  to  6  per  cent  each  of  nitrogen  and  phosphorus.  A 
mixture  containing  about  2  parts  of  tankage,  3  or  4  parts  of  acid 
phosphate,  i  part  of  kainit,  and  i  or  2  parts  of  filler  will  produce 
the  "  2-8-2  formula,"  with  about  2  per  cent  of  "insoluble 
phosphoric  acid  derived  from  animal  bone."  The  annual  pro- 
duction of  tankage  and  blood  amounts  to  about  i  million  tons. 

Dried  peat.  Train  loads  of  dried  peat  are  shipped  from  the  peat 
beds  of  Illinois  and  elsewhere  to  the  fertilizer  factories  for  use  as  a 
filler;  and  as  a  filler  it  is  said  to  be  superior  to  all  other  materials, 
because  it  is  a  very  effective  absorbent  and  thus  keeps  the  acidu- 
lated fertilizers  in  excellent  mechanical  condition.  Dried  peat  con- 
tains from  3  to  4  per  cent  of  nitrogen  which  may  be  "found"  by 
analysis,  although  the  nitrogen  in  peat  is  at  best  no  more  active 
than  that  in  the  ordinary  organic  matter  of  the  soil,  which  usually 
amounts  to  3000  to  5000  pounds  per  acre  in  the  plowed  soil,  so 
that  50  pounds  of  peat  in  200  pounds  of  "complete"  fertilizer 
would  not  appreciably  affect  the  crop. 


MANUFACTURED    COMMERCIAL   FERTILIZERS     525 

Cotton  seed.  Cotton-seed  meal  contains  about  i£  per  cent 
each  of  phosphorus  and  potassium.  Sometimes  the  whole  cotton 
seed,  containing  about  3  per  cent  of  nitrogen,  is  used  directly  as  a 
fertilizer,  but  as  practically  all  of  the  plant  food  remains  in  the 
hulls  and  cake  (after  the  oil  is  expressed) ,  the  meal  is  now  largely 
used,  and  more  profitably,  of  course,  unless  the  farmer  pays  more 
for  his  nitrogen  than  he  received  for  the  same  amount  in  seed, 
which  is  likely  to  be  the  case  if  he  buys  ready  mixed  "complete" 
fertilizer.  The  annual  production  of  cotton  seed  in  the  United 
States  amounts  to  about  6  million  tons. 

Fish  scrap.  Fish-scrap  meal  contains  about  8  per  cent  of  nitro- 
gen and  6  per  cent  of  phosphorus.  There  are  various  other  sources 
of  organic  nitrogen,  some  of  which,  like  hoof  meal,  furnish  avail- 
able nitrogen,  while  others,  like  hair,  wool  waste,  and  horn  meal, 
are  very  slowly  nitrified. 

Ammonium  sulfate.  Commercial  ammonium  sulfate  is  usually 
about  95  per  cent  pure,  containing  20  per  cent  or  more  of  nitrogen. 
It  is  obtained  by  washing  coal  gas  through  dilute  sulfuric  acid  and 
concentrating  the  liquid  until  the  ammonium  sulfate  crystallizes 
out.  About  100,000  tons  of  ammonium  sulfate  is  the  present 
annual  production  from  the  gas  plants  and  coke  ovens  in  the 
United  States,  and  the  production  is  likely  to  largely  increase, 
because  most  of  the  American  coke  ovens  are  still  wasting  the 
ammonia  produced. 

Sodium  nitrate.  Sodium  nitrate  of  commercial  grade  is  about 
95  per  cent  pure,  and  contains  15  per  cent  or  more  of  nitrogen.  It 
is  obtained  from  the  extensive  nitrate  beds  of  Chile,  where  it  is 
found  in  very  extensive  deposits,  thought  to  have  resulted  from 
the  decomposition  of  seaweed  in  connection  with  sea  salt.  The 
impure  material  is  leached  and  the  nitrate  secured  by  crystalliza- 
tion. The  exportation  began  about  1830  and  has  quite  steadily 
increased  from  8000  tons  in  1840  to  about  2  million  tons  in  1908, 
the  total  exportation  from  1830  to  1909  amounting  to  about  40 
million  tons,  which  is  about  one  sixth  of  the  estimated  1  amount  re- 
maining in  the  Chilian  and  Peruvian  beds.  The  export  duty 

1  The  estimates  of  ten  years  ago  placed  the  total  supply  at  81  million  tons,  but 
a  so-called  official  report  made  in  1909  (American  Fertilizer)  estimates  246  million 
tons. 


526  VARIOUS   FERTILITY   FACTORS 

yields  an  annual  revenue  of  more  than  $20,000,000,  or  about 
three  fourths  of  the  total  income  of  the  Chilian  government.  Most 
of  the  sodium  nitrate  imported  into  the  United  States  is  used  for 
the  manufacture  of  explosives. 

Calcium  nitrate.  The  artificial  fixation  of  atmospheric  nitrogen 
by  an  economic  and  practical  method  is  a  problem  whose  solution 
has  been  given  much  attention  for  many  years;  in  fact,  it  has  been 
the  dream  of  many  a  chemist  and  a  dream  which  has  only  recently 
been  realized. 

Calcium  nitrate  is  now  produced  to  a  limited  extent  (chiefly 
at  Notodden,  Norway,  by  the  aid  of  cheap  water  power)  by  the 
Birkeland-Eyde  process,  in  which  a  current  of  air  is  subjected  to 
powerful  electric  action,  which  results  in  the  formation  of  nitrogen 
tetroxid  (as  observed  by  Priestly  as  early  as  1775),  which  by 
somewhat  complex  reaction  with  water  and  oxygen  yields  nitric 
acid.  This  is  treated  with  lime  to  form  calcium  nitrate,  which  is 
obtained  in  crystallized  form,  Ca(NO3)2  4  H2O,  containing  about 
12  per  cent  of  nitrogen.  Calcium  nitrate  is  a  highly  deliquescent 
substance,  and  must  be  shipped  in  air-tight  containers.  In  an 
experiment  at  Rothamsted  10  grams  of  calcium  nitrate  (produced 
at  Notodden  in  1906)  absorbed  20  per  cent  of  water  and  became 
liquid  in  3  days,  and  in  10  days  about  50  per  cent  of  water  had 
been  absorbed. 

Calcium  cyanamid.  Calcium  cyanamid  is  also  a  product  result- 
ing from  the  artificial  fixation  of  atmospheric  nitrogen,  by  a  pro- 
cess recently  developed  by  Frank  and  Caro  of  Germany.  The 
primary  materials  used  in  the  process  are  limestone,  coke,  and 
nitrogen  gas.  Calcium  carbid  is  first  produced  by  heating  a 
mixture  of  burned  lime  and  coke  to  a  very  high  temperature  pro- 
duced by  an  electric  furnace: 

CaO  +  3  C  =  CaC2  +  CO. 

The  calcium  carbid  is  finely  ground  and  then  placed  in  closed 
retorts  and  heated  to  the  requisite  temperature  in  an  atmosphere 
of  nitrogen,  which  reacts  with  the  calcium  carbid  with  the  forma- 
tion of  calcium  cyanamid  and  separation  of  carbon : 

CaC2  +  2  N  =  CaCN2  +  C. 


MANUFACTURED    COMMERCIAL   FERTILIZERS     527 

The  nitrogen  gas  is  obtained  from  the  air,  either  by  passing 
air  through  a  hot  tube  containing  copper  turnings,  which  remove 
the  oxygen  by  forming  copper  oxid  (the  oxid  being  again  reduced 
by  substituting  coal  gas  for  air),  or  by  the  Linde  liquid-air  process, 
in  which  advantage  is  taken  of  the  difference  between  the  boiling 
points  of  nitrogen  (—  194°  C.)  and  oxygen  (—  184°  C),  the  nitro- 
gen being  evaporated  at  the  lower  temperature. 

Potassium  cyanid  is  a  well-known  substance  with  the  formula 
KCN,  or  N=C — K,  and  the  group  or  radicle,  N  =  C — ,  is  called 
cyanogen,  somewhat  as  the  group  —  NH4  is  called  ammonium,  and 
the  group  —  NH2  is  called  the  amido  group.  Cyanamid  contains 
the  two  groups,  thus  N  =  C — N=H2,  and  by  replacing  the  two 
hydrogen  atoms  by  one  bivalent  calcium  atom,  calcium  cyanamid 
(N=C — N=Ca)  is  produced.  Calcium  cyanamid  itself  con- 
tains 35  per  cent  of  nitrogen;  and,  if  the  product  could  be  made 
with  the  one  atom  of  free  carbon  as  the  only  impurity,  the  nitro- 
gen would  still  reach  30  per  cent,  but  about  one  third  of  the 
commercial  article  consists  of  other  impurities  (coal  ash,  lime,  cal- 
cium carbid,  sulfid,  phosphid,  etc.),  the  nitrogen  being  thus  re- 
duced to  about  20  per  cent.  An  analysis  of  a  commercial  sample 
gave  the  following  results: 

Calcium  cyanamid  (CaCN2) 57.0  per  cent 

Carbon 14.0  per  cent 

Lime  (CaO) 21.0  per  cent 

Silicon  dioxid 2.5  per  cent 

Iron  oxid 4.0  per  cent 

Calcium  sulfid,  phosphid,  and  carbonate      .     .     .  1.5  per  cent 

When  first  added  to  the  soil  the  commercial  calcium  cyanamid 
with  its  impurities  produces  an  injurious  effect  upon  young  plants, 
and  to  avoid  this  it  is  applied  a  week  or  two  before  seeding.  For 
the  same  reason  it  cannot  safely  be  used  as  a  top-dressing.  It  has 
a  tendency,  because  of  its  lime  content,  to  absorb  moisture  and 
carbon  dioxid  from  the  air,  and  for  protection  is  usually  treated 
with  a  small  amount  of  heavy  petroleum.  A  ten-gram  sample 
of  calcium  cyanamid  exposed  for  1 2  days  at  Rothamsted  increased 
30  per  cent  in  weight,  and  some  loss  of  ammonia  occurred. 


528  VARIOUS   FERTILITY   FACTORS 

Many  pot-culture  and  field  experiments  have  been  made  with 
calcium  cyanamid  which  show  that  when  properly  used  the  nitrogen 
in  this  form  has  about  the  same  value  as  in  ammonium  sulfate. 

When  heated  with  water  under  pressure,  calcium  cyanamid 
decomposes  with  the  formation  of  calcium  carbonate  and  ammonia, 
as  indicated  by  the  following  equation: 

CaCN2  +  3  H2O  =  CaCO3  +  2  NH3. 

For  long-distance  shipping  the  final  product  from  the  artificial 
fixation  of  atmospheric  nitrogen  is,  in  the  opinion  of  the  author> 
to  be  ammonium  nitrate,  made  by  using  the  ammonia  thus  pro- 
duced as  a  base  for  neutralizing  the  nitric  acid  obtained  in  the 
Birkeland-Eyde  process. 

NH3  +  HNO3  =  NH4NO3. 

The  ammonium  nitrate  thus  formed,  free  from  mineral  im- 
purities, would  contain  35  per  cent  of  nitrogen.  To  produce  this 
compound  would  require  five  plants:  (i)  for  nitrogen  gas,  (2) 
for  calcium  carbid,  (3)  for  calcium  cyanamid,  (4)  for  ammonia,  and 
(5)  for  nitric  acid. 

A  publication  issued  June  i,  1907,  by  the  American  Cyanamid 
Company,  estimates  that  the  original  cost  of  a  complete  plant  for 
the  production  of  10,000  tons  per  annum  of  calcium  cyanamid 
would  amount  to  $444,000,  including: 

$155,000  for  the  calcium  carbid  plant, 
70,000  for  the  Linde  nitrogen  plant, 
145,000  for  the  calcium  cyanamid  plant, 
74,000  for  expense  not  itemized. 

This  estimate  of  $444,000  does  not  include  the  cost  of  the 
power  plant,  it  being  assumed  that  a  separate  company  will  be 
organized  to  furnish  the  power  by  utilizing  a  natural  waterfall. 

In  connection  with  elaborated  estimates  as  to  the  actual  cost  of 
producing  cyanamid  nitrogen  in  such  a  plant,  the  following  state- 
ments are  made  in  this  publication : 

"  Throughout  all  estimates  of  costs  of  operating  it  is  assumed  that  power 
costs  the  Cyanamid  Company  $15  per  24-hour  horse  power  per  annum,  meas- 
ured on  the  switchboard  of  the  power  company  supplying  the  power.  It  is 


MANUFACTURED    COMMERCIAL   FERTILIZERS     529 

assumed  also  that  the  power  company  and  the  works  of  the  Cyanamid  Com- 
pany are  so  close  together  that  there  will  be  no  appreciable  loss  in  electric 
transmission." 

"  Thus  the  total  estimated  cost,  including  interest  upon  the  estimated  in- 
vestment of  $444,000,  is  $45  per  metric  ton,'  equivalent  to  22^  cents  per 
kilogram  of  nitrogen,  or  10  cents  per  pound." 

It  should  be  noted  that  this  10  cents  per  pound  for  cyanamid 
nitrogen  is  the  estimated  cost  to  the  manufacturers,  and  that  it 
includes  no  allowance  for  transportation  of  the  finished  product 
from  the  factory  to  the  farmer,  no  allowance  for  the  cost  of  adver- 
tising and  selling,  and  no  allowance  for  any  profit  to  anybody. 

It  should  be  noted,  too,  that  the  4  million  pounds  of  combined 
nitrogen  which  such  a  plant  could  produce  in  one  year  would  be 
sufficient,  if  none  were  lost  in  drainage  waters,  to  meet  the  "  grow- 
ing demands  "  of  the  average  corn  crop  of  the  United  States  for 
less  than  200  minutes. 

A  calcium  cyanamid  factory  is  located  at  Niagara  Falls. 

SOURCES  OF  COMMERCIAL  POTASSIUM 

There  are  three  important  sources  of  commercial  potassium: 
(i)  the  German  mines,  (2)  the  salts  recovered  from  the  evapora- 
tion of  sea  water,  and  (3)  wood  ashes. 

Potassium  salts  of  Germany.  The  very  extensive  salt  deposits 
in  the  region  of  the  Harz  Mountains  in  northern  Germany  con- 
stitute at  present  by  far  the  most  important  source  of  commercial 
potassium.  These  deposits  were  discovered  by  borings  made  near 
Stassfurt  in  1857,  and  the  potassium  salts  are  found  chiefly  in 
strata  overlying  the  much  thicker  stratum  of  common  rock  salt. 
It  is  estimated  that  these  German  salt  deposits  cover  an  area  of  a 
million  acres,  and  that  the  supply  of  potassium  which  they  con- 
tain is  sufficient  to  supply  the  present  rate  of  mining  for  190,000 
years. 

It  is  thought  that  these  salt  and  potash  beds  were  formed  in 
ancient  geologic  time  by  the  evaporation  of  sea  water  confined  in 
lakes  somewhat  like  the  Dead  Sea,  or  Great  Salt  Lake,  except  that 
there. was  at  times  connection  with  the  ocean  which  supplied  the 
salt  water.  Evaporation  carries  off  water  vapor  and  leaves  the 
salts  in  solution,  but  if  the  evaporation  proceeds  far  enough,  the 


530  VARIOUS   FERTILITY   FACTORS 

less  soluble  salts,  such  as  (i)  calcium  sulfate  (gypsum)  and  (2) 
sodium  chlorid  (common  salt),  begin  to  separate  in  crystals  which 
settle  to  the  bottom;  and  with  further  evaporation  of  water  the 
more  soluble  salts  of  potassium  and  magnesium  finally  separate 
in  crystals  which  are  deposited  in  strata  above  the  principal  salt 
deposits. 

After  vast  amounts  of  water  had  been  evaporated  and  immense 
quantities  of  salts  deposited,  these  accumulations  sometimes  be- 
came covered  with  drift  material  (clay  etc.)  several  feet  in  thick- 
ness, and  at  a  later  period  the  sea  water  again,  came  in  and  by 
evaporation  left  a  second  stratum  of  calcium  sulfate,  and  above  it 
another  immense  salt  deposit. 

The  total  thickness  of  these  various  strata  is  about  5000  feet 
at  Stassfurt.  There  are  many  variations  and  irregularities,  but 
in  the  main  the  lower  stratum  consists  largely  of  calcium  sulfate; 
next  above  is  the  sodium  chlorid  deposit  of  great  depth;  then  a 
layer  of  the  mineral  polyhalite,  composed  of  the  sulfates  of  po- 
tassium, calcium,  and  magnesium,  kieserite  (magnesium  sulfate), 
and  finally  a  stratum  varying  from  50  to  130  feet  in  thickness, 
which  consists  largely  of  carnallite,  a  double  salt  of  potassium  and 
magnesium  chlorid. 

In  some  places  the  overlying  clay  or  earth  became  cracked,  and 
water  entered  from  the  surface,  so  that  more  or  less  of  the  various 
salts  were  dissolved  and  redeposited  in  veins  or  pockets  in  com- 
pounds or  forms  not  commonly  found  in  the  more  general  strata. 
Thus  were  formed  comparatively  small  beds  of  kainit,  sylvanite,  and 
hartsalz.  More  than  thirty  different  compounds  or  minerals  are 
found  in  these  Stassfurt  deposits,  and  at  least  a  dozen  of  these 
contain  more  or  less  potassium. 

By  far  the  most  abundant  source  of  potassium  is  the  carnallite 
stratum,  but  even  the  pockets  or  beds  of  kainit,  sylvanite,  and 
hartsalz  are  of  great  importance.  The  following  are  commonly 
accepted  as  the  formulas  which  represent  these  minerals: 

Carnallite,  KC1  MgCl2  6H2O. 

Kainit,  K2SO4  MgSO4  MgCl2  6  H2O. 

Sylvanite,  K2SO4  MgSO4  KC1  MgCl2  NaCl  6H2O. 

Hartsalz,  KC1  MgSO4  NaCl  H2O. 


MANUFACTURED    COMMERCIAL   FERTILIZERS     531 

There  are  three  principal  potassium  fertilizers  brought  to 
America  from  Germany:  potassium  chlorid,  kainit,  and  potassium 
sulfate.  The  commerical  kainit  usually  consists  of  two  thirds  of 
the  mineral  and  one  third  sodium  chlorid,  and  contains  about 
10  per  cent  of  potassium.  It  is  ground  and  used  very  generally 
for  direct  application. 

Potassium  chlorid  is  obtained  from  carnallite,  and  potassium 
sulfate  from  kainit,  by  dissolving  the  minerals  and  allowing  these 
salts  to  crystallize  out  at  suitable  temperatures.  Commercial 
potassium  chlorid  is  usually  at  least  80  per  cent  pure,  while  the 
sulfate  has  a  purity  of  nearly  95  per  cent.  Each  contains  about 
42  to  43  percent  of  potassium.  Potassium  sulfate  is  also  produced 
from  potassium  chlorid  and  sulfuric  acid  in  the  manufacture  of 
hydrochloric  acid,  for  which  sodium  chlorid  was  formerly  used. 

Sylvanite  and  hartsalz  (hard  salt)  are  sometimes  ground  and 
applied  in  the  crude  state,  but  the  concentrated  salts  may  also 
be  derived  from  them  by  solution  and  recrystallization. 

Potassium-magnesium  sulfate,  or  "  double  manure  salt,"  is 
another  Stassfurt  preparation  which  is  used  to  some  extent.  It 
contains,  as  found  in  the  market,  about  20  per  cent  of  potassium. 
Its  special  value,  like  that  of  potassium  sulfate,  is  for  use  in  fer- 
tilizing those  crops  whose  "  quality  "  is  injured  by  salts  containing 
chlorin,  particularly  the  tobacco  crop. 

Wood  ashes.  Unleached  wood  ashes  commonly  contain  5  per 
cent  of  the  element  potassium  (as  carbonate),  50  per  cent  of  cal- 
cium carbonate,  and  .5  per  cent  of  phosphorus.  On  most  soils 
they  are  likely  to  be  more  valuable  for  the  lime  than  for  their 
potassium  content;  and,  when  applied  at  the  rate  of  a  ton  or 
more  per  acre,  even  the  phosphorus  added  is  more  than  that  con- 
tained in  200  or  300  pounds  of  the  common  "  complete  "  commer- 
cial fertilizer. 

Potassium  from  sea  water.  Where  common  salt  is  obtained 
from  the  evaporation  of  sea  water,  as  has  been  done  to  some  extent 
on  the  southern  coast  of  France,  potassium  is  secured  as  a  by- 
product from  the  concentration  of  the  "  mother  liquor,"  and  one 
may  conceive  of  unlimited  supplies  being  produced  in  this  manner 
where  the  climatic  conditions  and  other  natural  advantages  can 
be  utilized,  as  on  an  arid  coast  and  under  a  tropical  sun,  especially 


532  VARIOUS   FERTILITY   FACTORS 

where  tidal  power  could  fill  extensive  reservoirs  and  where  a 
mountain  stream  could  serve  to  dissolve  and  remove  the  salt 
deposit  after  the  "  mother  liquor  "  is  drawn  off  for  further  con- 
centration. 

It  is  sometimes  claimed  that  potassium  salts,  especially  kainit, 
have  some  power  to  prevent  damage  from  fungous  diseases  and 
injurious  insects,  but  it  may  be  questioned  whether  the  effect 
is  direct  or  indirect ;  data  already  given  show  very  conclusively 
that  not  only  potassium  salts,  but  also  the  salts  of  magnesium 
and  sodium  (usually  to  a  smaller  extent),  produce  marked  benefit 
in  many  instances.  In  most  cases,  however,  any  influence  which 
aids  directly  or  indirectly  in  the  proper  nourishment  of  the  plant 
will  thus  enable  the  plant  itself  better  to  resist  attacks  of  insects 
or  disease.  The  author  has  frequently  observed  that  insect  in- 
juries are  much  more  apparent  on  corn  grown  on  poor  land  than 
on  adjoining  plots  treated  with  phosphorus  in  connection  with 
farm  manure  or  crop  residues. 

Where  the  soil  is  markedly  deficient  in  potassium,  as  compared 
with  normal  soils,  as  is  the  case  with  certain  peaty  swamp  soils, 
and  where  the  application  of  potassium  salts  on  such  soils  produces 
marked  benefit,  while  sodium  salts  produce  practically  no  benefit 
(see  Table  91),  there  can  be  no  question  regarding  the  need  and 
value  of  potassium  for  its  own  sake;  and  even  where  the  soil  con- 
tains normal  amounts  of  potassium,  if  enormous  crops  are  to  be 
grown  that  draw  very  heavily  on  potassium,  as  the  40  to  50  tons  per 
acre  of  mangels  on  Barn  field  at  Rothamsted  (see  Table  Jib), 
the  time  will  come  when  potassium  must  be  returned.  (This,  how- 
ever, is  also  the  case  with  magnesium  and  calcium.) 

On  the  other  hand,  where  the  plowed  soil  contains  sufficient 
total  potassium  to  meet  the  draft  upon  it  for,  say,  two  thousand 
years,  and  where  sodium  or  magnesium  salts  produce  about  the 
same  effect  as  potassium  salts,  and  where  potassium  produces 
little  or  no  effect  if  applied  in  connection  with  liberal  amounts 
of  decaying  organic  matter,  the  conclusion  may  be  safely  drawn 
that  the  addition  of  commercial  potassium  is  not  essential  in 
adopting  systems  of  permanent  agriculture,  for  even  the  slight 
erosion  that  occurs  on  nearly  level  lands  will  possibly  provide  an 
absolutely  permanent  supply. 


CHAPTER  XXVIII 

CROP  STIMULANTS  AND  PROTECTIVE  AGENTS 

A  CLEAR  distinction  should  be  made  betweeen  the  use  of  plant 
food  in  systems  of  permanent  agriculture  and  the  use  of  crop 
stimulants  or  crop  "  protectors."  Unquestionably  there  are  con- 
ditions under  which  the  use  of  some  particular  substance,  other 
than  plant  food,  will  produce  a  sufficient  increase  in  the  yield  of  the 
crop  for  which  it  is  applied  to  more  than  pay  the  cost;  and,  further- 
more, the  use  of  such  material  may  in  some  cases  be  advisable,  but 
it  should  be  used  with  intelligence  and  full  understanding  of  its 
effect. 

Land-plaster.  Land-plaster  (native  calcium  sulfate)  is  a  well- 
known  crop  stimulant,  but  it  contains  neither  nitrogen,  phos- 
phorus, potassium,  nor  lime,  supplies  no  plant  food  of  commercial 
value  and  has  no  power  to  correct  soil  acidity,  and  its  physical 
effect  on  the  soil  is  probably  injurious  rather  than  beneficial. 
In  fact,  it  is  the  common  report  that  the  soil  tends  to  become  hard 
and  more  compact  with  the  long-continued  use  of  land-plaster; 
but  whether  this  effect  is  wholly  due  to  the  wearing  out  of  the 
organic  matter,  or  in  some  part  due  to  the  cementing  properties  of 
the  calcium  sulfate,  cannot  be  stated  with  certainty.  When  de- 
hydrated, calcium  sulfate  becomes  plaster  of  Paris,  and  it  is  a 
constituent  of  different  cementing  materials. 

The  temporary  beneficial  effect  of  land-plaster  is  probably  due 
to  its  chemical  action  in  the  soil.  It  may  convert  more  or  less  of 
the  supposedly  difficultly  available  iron  phosphate  into  the  more 
readily  available  tricalcium  phosphate,  as  indicated  by  the  follow- 
ing equation : 

2  FePO4  +  3  CaSO4  =  Ca3  (PO4)2  +  Fe2  (SO4)3. 

Very  possibly  this  or  some  similar  reaction  occurs  to  a  limited 
extent  when  calcium  sulfate  is  applied  to  a  soil  containing  iron 

533 


534  VARIOUS   FERTILITY    FACTORS 

phosphate.  Another  possible  reaction  may  result  in  the  liberation 
of  potassium  or  magnesium  from  polysilicates,  as  roughly  indicated 
by  the  following  equation: 

AlFeMgNaKx+2  (SiO3)y  (H2O)Z  +  CaSO4 

=  AlFeMgNaKxCa  (SiO3)y(H2O) 


With  large  supplies  of  potassium  present  in  polysilicates,  heavy 
applications  of  calcium  sulfate  would  doubtless  liberate  some 
potassium  sulfate,  although  under  the  opposite  conditions  mass 
action  would  force  the  reverse  reaction;  that  is,  heavy  appli- 
cations of  potassium  sulfate  to  a  soil  containing  much  calcium  in 
polysilicates  would  liberate  some  calcium  sulfate. 

The  potassium  sulfate  liberated  from  the  insoluble  silicate,  as 
indicated  above,  may  serve  directly  as  plant  food,  or  it  may  react 
to  increase  the  availability  of  phosphorus,  thus  : 

Ca3  (PO4)2  +  2  K2SO4  =  CaK4  (PO4)2  +  2  CaSO4. 

These  equations  are  given  to  show  some  of  the  possible  reactions 
that  may  occur  when  a  soluble  salt  is  added  to  the  soil.  A  dozen 
different  reactions  may  be  taking  place  at  the  same  time  within 
the  same  cubic  inch  of  soil,  and  it  is  easily  possible  that,  while 
one  reaction  is  taking  place  in  one  part  of  the  cubic  inch,  the 
reaction  is  running  in  reverse  order  in  another  part,  depending 
upon  the  mass,  composition,  and  concentration  of  the  insoluble 
and  soluble  salts. 

If  a  solution  of  ammonium  sulfate  or  potassium  chlorid  is  per- 
colated through  a  stratum  of  soil,  an  examination  will  usually 
show  that,  while  ammonium  or  potassium  passed  into  the  soil, 
calcium  and  magnesium  have  passed  out  in  the  percolate.  If 
tricalcium  phosphate  be  shaken  with  pure  water,  practically  no 
phosphorus  will  be  found  in  the  filtrate;  but  if  a  solution  of  some 
neutral  salt,  such  as  sodium  chlorid  or  potassium  nitrate,  be  sub- 
stituted for  the  pure  water,  very  appreciable  amounts  of  phosphorus 
are  dissolved. 

Land-plaster  has  been  much  used  in  some  parts  of  the  North 
Central  and  Eastern  states,  and  for  a  time  it  usually  gives  quite 
profitable  results;  but  finally,  the  element  of  real  value  that  has 
been  liberated  by  the  action  of  the  land-plaster  becomes  so  depleted 


CROP   STIMULANTS   AND    PROTECTIVE   AGENTS     535 

that  even  heavy  applications  of  plaster  fail  to  liberate  sufficient 
for  profitable  crops,  and  thus  the  plastered  land  is  made  poorer 
than  the  untreated  land. 

A  common  method  of  advertising  has  been  to  write  the  word 
PLASTER  with  a  heavy  application  of  the  material  in  large  letters 
on  a  cultivated  field  in  view  of  the  public  road.  In  the  larger, 
greener  growth  of  grain  crops  or  grass,  the  word  PLASTER  can  be  read 
by  the  passers-by;  and  thus  the  landowner  is  induced  to  plaster 
his  whole  field.  If,  however,  he  would  only  apply  plaster  year  after 
year  where  the  word  was  first  written,  the  time  would  come  when 
the  word  could  not  be  read;  and,  if  he  still  continued  the  applica- 
tions, ultimately  he  would  again  be  able  to  read  PLASTER,  if  we 
may  judge  from  the  testimony  of  common  experience. 

Common  salt.  Common  salt  (sodium  chlorid)  is  sometimes 
used  as  a  crop  stimulant,  but  its  beneficial  effect  is  likely  to  be  even 
less  durable  than  that  of  land-plaster.  However,  where  common  salt 
or  other  soluble  salts,  such  as  sodium  sulfate  or  magnesium  sulfate, 
or  mixtures  like  kainit,  are  applied  in  connection  with  sufficient 
supplies  of  phosphorus,  nitrogen,  and  lime,  the  effect  of  the  stimu- 
lant must  be  confined  chiefly  to  holding  the  phosphorus  or  other 
necessary  elements  in  available  form  and  to  liberating  potassium 
from  the  soil;  and  where  the  natural  supply  of  potassium  is  ex- 
tremely large,  the  beneficial  effect  of  the  applied  salt  may  continue 
for  many  years,  as  is  well  shown  in  the  results  from  Rothamsted. 

Kainit.  Kainit,  of  course,  also  supplies  some  potassium,  and  is 
thus  in  some  part  a  fertilizer,  though  in  large  part  a  stimulant. 
To  some  extent  this  is  also  true  of  the  common  acid  phosphate, 
which  contains  phosphorus  mainly  in  the  form  of  a  soluble  acid 
salt,  and  twice  as  many  molecules  of  manufactured  land-plaster : 

Ca3  (P04)2  +  2  H2S04  =  CaH4(P04)2  +  2  CaSO4. 

It  is  difficult  to  conceive  of  a  more  effective  combination  than 
about  200  pounds  per  acre  of  a  mixture  of  acid  phosphate  and  kainit 
applied  twice  for  each  five-year  rotation  of  corn,  oats,  wheat,  clover, 
and  timothy.  With  all  crops  removed,  such  a  system  would  doubt- 
less as  thoroughly  deplete  the  soil  as  any  that  could  be  devised, 
clover  itself,  used  in  this  way,  being  a  very  powerful  soil  stimulant. 
If  anything  could  be  added  to  hasten  the  action,  an  application 


536  VARIOUS   FERTILITY   FACTORS 

of  five  tons  of  farm  manure  about  once  in  ten  years  (spread  very 
uniformly,  and  an  occasional  dressing  of  burned  lime,  would  make 
this  system  of  ultimate  land  ruin  very  complete. 

A  mixture  of  300  pounds  of  acid  phosphate  and  100  pounds  of 
kainit  in  five  years  would,  with  the  manure  system,  furnish  about 
5  pounds  of  nitrogen,  5  pounds  of  phosphorus,  and  6  pounds  of 
potassium  per  acre  per  annum;  whereas,  crops  as  large  as  we  ought 
to  try  to  produce  would  remove  from  the  soil  as  a  yearly  average 
about  TOO  pounds  of  nitrogen,  20  pounds  of  phosphorus,  and  80 
pounds  of  potassium  (see  Table  13).  When  crops  one  half  as  large 
are  produced  under  such  a  system  of  fertilization,  the  soil  under  the 
action  of  these  stimulants  must  furnish  about  nine  tenths  of  the 
nitrogen,  half  of  the  phosphorus,  and  six  sevenths  of  the  potassium 
required  for  the  crops.  An  invoice  of  his  stock  of  fertility  will  help 
the  landowner  to  plan  wisely  for  the  future,  because  he  can  thus 
know  in  advance  what  the  ultimate  effect  must  be  of  such  systems. 

Protective  agents.  As  protective  agents  we  may  include  materials 
which  tend  to  ward  off  disease  or  insect  enemies;  and  the  effect 
may  be  produced  by  substances  destructive  to  fungi  or  repellent 
to  insects.  Kainit  is  thought  to  act  sometimes  as  a  fungicide,  and 
tankage  is  held  by  some  to  prevent  attack  from  certain  insects. 

Any  treatment  which  hastens  the  normal  growth  of  the  plant 
usually  helps  the  plant  to  resist  or  overcome  the  attack  of  insects 
or  disease;  and  it  is  apparently  true  that  imperfect  or  abnormal 
plants  are  more  likely  to  suffer  from  such  attacks  than  normal, 
healthy  plants.  It  has  been  suggested  that  sucking  insects  prefer 
the  concentrated  sap  of  weak  or  somewhat  withered  plants  to  that 
of  vigorous  succulent  plants.  Doctor  Forbes  has  suggested  that 
the  very  dilute  juice  of  a  rapidly  growing  plant  may  constitute  a 
starvation  diet  for  healthy  insects;  in  other  words,  that  the 
capacity  of  the  insect  for  such  juice  is  not  sufficient  to  furnish 
it  with  the  amount  of  nutrition  necessary  for  maintenance  and 
reproduction. 

It  is  common  observation  that  chinch  bugs  may  attack  and 
destroy  wheat  that  would  otherwise  yield  10  or  15  bushels  per  acre, 
while  wheat  growing  in  the  same  field  on  land  capable  of  producing 
30  bushels  or  more  per  acre  is  not  attacked.  The  author  has  noted 
in  several  different  seasons  that  corn  growing  on  land  that  will 


CROP   STIMULANTS   AND    PROTECTIVE   AGENTS     537 

yield  40  to  60  bushels  per  acre  has  been  very  severely  injured  by 
the  colaspis  root  worm,  while  no  apparent  damage  was  done  on 
adjoining  well-fertilized  plots  which  produced  80  to  100  bushels 
per  acre,  although  the  insects  were  found  in  both  parts  of  the  field. 
In  any  or  all  of  these  ways  small  applications  of  fertilizers  or  stimu- 
lants may  produce  results  in  crop  yields  far  beyond  the  direct 
nutrient  value  of  the  plant  food  applied. 

The  practice  is  somewhat  common  in  places  of  coating  seed 
corn  by  stirring  with  a  paddle  dipped  in  warm  tar,  and  to  some 
extent  castor  oil  has  been  used  for  the  same  purpose,  the  appli- 
cation being  made  two  or  three  weeks  before  planting  so  that  the 
oil  coating  may  have  time  to  "  dry  on."  Turpentine  has  also  been 
used,  and  some  have  advised  putting  powdered  sulfur  with  the 
seed  in  the  planter  boxes.  These  of  course  are  solely  protective 
agents,  if  they  have  any  value.  Their  use  is  based  upon  experi- 
ence, however,  and  not  upon  experiment,  and  thus  far  the  practice 
seems  to  rest  upon  no  better  foundation  than  that  of  planting 
potatoes  "by  the  moon,"  or  "witching"  for  water,  an  "art" 
which  fails  to  find  water  twice  in  the  same  place  if  the  operator 
is  blindfolded. 


CHAPTER  XXIX 

CRITICAL   PERIODS    IN   PLANT   LIFE 

IN  this  connection  we  may  well  consider  another  cause  of 
differences  in  crop  yields  quite  out  of  proportion  to  the  difference 
in  soil  treatment.  There  may  be,  and  often  are,  critical  periods  in 
the  life  of  plants,  when  some  small  measure  of  assistance  may 
change  prospective  failure  into  marked  success.  Thus,  it  is  not 
infrequently  a  question  of  life  or  death  with  the  clover  plant  when 
the  nurse  crop  is  removed;  and,  while  most  of  the  plants  may  die 
at  that  time  on  untreated  land,  a  good  stand  of  clover  may  be  saved 
where  a  very  light  application  had  been  made  of  manure,  fertilizer, 
or  soil  stimulant.  The  nutrient  value  of  the  application  may  not 
be  sufficient  for  half  a  ton  of  clover,  but  the  difference  in  yield  may 
amount  to  one  or  two  tons;  and  from  the  larger  crop  larger  resi- 
dues are  left  on  and  in  the  soil,  resulting  in  a  larger  crop  of  grain 
the  following  year.  Thus,  enormous  credit  may  be  given,  which  is 
not  at  all  deserved,  on  the  basis  of  total  plant  food  concerned. 

One  of  the  most  critical  periods  in  the  life  of  the  corn  plant  is 
at  the  time  the  ears  are  forming,  and  an  ample  supply  of  moisture 
appears  to  be  especially  necessary  at  that  time.  If  a  severe  sum- 
mer drouth  is  coincident  with  this  critical  period,  the  yield  of 
grain  is  likely  to  be  small;  and  any  soil  treatment  which  has  the 
effect  either  of  hastening  or  retarding  the  development  of  the  plant, 
and  thus  of  bringing  the  earing  time  either  before  or  after  the 
drouth,  may  very  markedly  affect  the  crop  yield. 

The  farmer  is  usually  most  anxious  for  conditions  under  which 
his  wheat  will  "  fill  "  well,  and  since  this  is  influenced  very  appre- 
ciably by  the  temperature  during  this  critical  period,  it  follows  that 
very  marked  effects  upon  both  yield  and  quality  may  sometimes 
result  from  any  soil  treatment  that  causes  the  wheat  to  "  fill  " 
either  a  few  days  earlier  or  a  few  days  later  than  on  the  untreated 
land.  On  the  other  hand,  the  treatment,  whether  applied  as  a  crop 

538 


CRITICAL   PERIODS   IN   PLANT  LIFE  539 

stimulant  or  in  a  system  of  permanent  soil  improvement,  may  some- 
times be  the  means  of  bringing  this  critical  period  at  the  time  when 
the  weather  conditions  are  most  unfavorable,  while  the  untreated 
land  may  mature  a  larger  crop  at  the  more  favorable  time. 

An  instance  has  been  reported  of  a  field  treated  with  half  a  ton 
per  acre  of  raw  phosphate  having  produced  a  crop  of  45  bushels  of 
oats  free  of  rust,  whereas  only  20  bushels  of  badly  rusted  oats  were 
produced  from  similar  seed  on  adjoining  untreated  land.  Two 
influences  may  help  to  produce  this  difference:  the  added  phos- 
phorus tends  to  balance  the  food  ration  and  thus  to  strengthen  the 
oats  against  the  fungous  disease  (and  against  lodging,  as  well), 
and  also  to  hasten  the  maturity  by  which  the  crop  escapes  the  rust 
which  might  attack  the  plants  maturing  later  and  perhaps  under 
weather  conditions  more  favorable  for  the  development  of  the 
disease.  As  was  stated  by  the  author  to  the  farmer  who  reported 
this  experience,  the  marked  difference  in  yield  is  not  to  be  credited 
even  largely  to  the  phosphorus  because  of  the  plant  food  for  its 
own  sake,  but  rather  to  a  combination  of  influences  to  which  the 
added  phosphorus  proved  to  be  the  key. 

While  such  examples  may  serve  temporarily  as  good  advertise- 
ments for  the  treatment  applied,  they  are  just  as  misleading  for 
wide  application  as  are  the  occasional  reports  of  damage  to  crops 
produced  by  applying  manure.  All  of  this  serves  to  emphasize 
the  importance  of  having  some  fundamental  knowledge  upon  which 
to  base  definite  systems  of  permanent  agriculture.  For  this  pur- 
pose we  must  rely  primarily  upon  the  absolute  facts  furnished 
by  chemistry  and  mathematics  and  be  guided  only  by  the  results 
of  carefully  conducted  and  long-continued  experiments.  Single 
examples  can  be  found  in  support  of  almost  any  practice  or  theory 
that  can  be  advanced;  but  a  mere  experience,  though  it  be  repeated, 
invariably  with  the  same  result,  for  fourscore  times,  furnishes  no 
proof  whatever  that  the  octogenarian  will  live  to  celebrate  another 
birthday. 

A  small  amount  of  readily  available  plant  food,  such  as  50  pounds 
of  sodium  nitrate  per  acre  as  a  top  dressing  for  wheat  on  poor  land 
in  a  cold  spring,  may  produce  a  sufficient  increase  in  yield  to  more 
than  pay  the  cost  of  the  nitrate.  Likewise,  100  pounds  of  "  am- 
moniated  bone  and  potash,"  carrying  perhaps  2  pounds  of  nitro- 


540  VARIOUS   FERTILITY   FACTORS 

gen,  4  pounds  of  phosphorus,  and  2  of  potassium  may  be  dropped 
in  or  near  the  hill  of  corn  with  a  "  fertilizer  attachment  "  to  the 
planter,  and,  under  adverse  conditions  of  soil  and  season,  the  crop 
increase  may  show  some  profit.  It  should  be  clearly  understood, 
however,  that  all  such  systems  of  fertilizing  are  of  themselves 
only  an  aid  to  soil  depletion,  because  the  "  good  start  "  thus  given 
to  the  crop  enables  it  to  draw  upon  the  soil  itself  for  larger  supplies 
of  one  or  more  elements  of  plant  food  than  would  be  furnished 
by  the  untreated  soil  and  the  fertilizer  applied. 

Quite  independent  of  any  such  practices,  the  landowner  should 
make  ample  provision  for  maintaining  the  fertility  of  the  soil, 
on  normal  soil,  by  large  use  of  phosphorus  and  farm  manure  or 
legume  crops  and  crop  residues,  sufficient  limestone  being  applied 
when  necessary  to  prevent  or  correct  soil  acidity.  Where  this  is 
done,  however,  the  use  of  "  starters  "  is  usually  unnecessary  and 
unprofitable.  Indeed,  the  dropping  of  a  small  quantity  of  fertilizer 
in  the  hill  of  corn  for  near  it)  is  sometimes  a  source  of  damage, 
not  so  much  because  it  may  injure  the  seed  or  young  plant,  but 
because  it  does  not  encourage  the  normal  development  of  the  root 
system  in  proportion  to  the  early  growth  of  the  plant,  and  as  a 
consequence  the  crop  may  suffer  from  drouth  later  in  the  season 
much  more  than  the  unfertilized  corn. 


CHAPTER   XXX 

FARM   MANURE 

THE  value  of  farm  manure  is  governed  largely  by  four  modify- 
ing and  somewhat  related  factors. 

First,  the  composition  of  the  materials  used  for  feed  and  bedding. 

Second,  the  dryness,  or  dry-matter  content,  of  the  manure. 

Third,  the  preservation  or  stage  of  decomposition  or  waste  of 
the  manure. 

Fourth,  the  kind  of  animals  producing  the  manure. 

As  a  general  average  a  ton  of  fresh-mixed  cattle  and  horse  manure 
contains  about  500  pounds  of  dry  matter,  10  pounds  of  nitrogen, 
2  pounds  of  phosphorus,  and  8  pounds  of  potassium.  It  would  be 
produced  from  about  810  pounds  of  air-dry  feed  (yielding  270 
pounds  of 'dry  excrement)  and  270  pounds  of  air-dry  bedding 
(containing  230  pounds  of  dry  matter).  On  this  basis,  four  tons 
of  air-dry  feed  and  bedding  (used  in  the  proportion  of  3  to  i) 
would  produce  about  7^  tons  of  average  fresh  manure  containing 
25  per  cent  of  dry  matter  and  75  per  cent  of  water. 

Roughly,  this  represents  the  theoretically  possible  production 
of  manure  on  the  farm,  if  all  crops  grown  are  used  for  feed  and 
bedding.  If  the  crops  sold  from  the  farm  amount  to  one  third  of 
the  total  produced,  and  if  one  fifth  of  the  manure  made  is  lost  be- 
fore it  is  applied  to  the  land,  then  for  every  ton  of  air-dry  produce 
harvested  and  removed  from  the  land  one  ton  of  manure  could  be 
returned. 

If  we  count  85  per  cent  of  dry  matter  in  the  air-dry  feed  and 
bedding,  and  66|  as  the  average  digestion  coefficient  for  the  dry 
matter  in  the  food  consumed  (see  Table  29),  and  75  per  cent  of 
the  nitrogen  and  phosphorus  and  90  per  cent  of  the  potassium  re- 
turned in  the  manurial  excrements,  then  a  ration  of  500  pounds  of 
clover  hay  and  310  pounds  of  corn,  with  270  pounds  of  wheat 


542  VARIOUS   FERTILITY   FACTORS 

straw  for  bedding,  would  make  a  ton  of  manure  containing  500 
pounds  of  dry  matter,  about  12  J  pounds  of  nitrogen,  2  pounds  of 
phosphorus,  and  p|  pounds  of  potassium.  Or  a  ration  containing 
500  pounds  of  timothy  hay  and  310  pounds  of  oats,  with  270  pounds 
of  oat  straw  for  bedding,  would  make  a  ton  of  manure  containing 
500  pounds  of  dry  matter,  about  n  pounds  of  nitrogen,  1.7  pounds 
of  phosphorus,  and  9  pounds  of  potassium.  Some  loss  of  nitrogen 
is  likely  to  occur  by  volatilization,  and  both  nitrogen  and  potassium 
are  very  likely  to  be  lost  in  the  liquid  excrement. 

For  the  most  common  rations  used  in  live-stock  farming,  10,  2, 
8  represent  very  approximately  the  average  pounds  of  the  three 
elements,  nitrogen,  phosphorus,  and  potassium,  in  a  ton  of  "  aver- 
age fresh  manure."  By  leaching  and  fermentation  the  dry  matter, 
nitrogen,  and  potassium  are  lost  in  approximately  the  same  pro- 
portion, but  the  phosphorus  is  lost  only  about  half  as  rapidly,  so 
that  one  ton  of  average  yard  manure,  resulting  from  perhaps  two 
tons  of  fresh  manure,  contains  about  500  pounds  of  dry  matter, 
10  pounds  of  nitrogen,  3  pounds  of  phosphorus,  and  8  pounds  of 
potassium,  one  half  of  the  dry  matter,  nitrogen,  and  potassium, 
and  one  fourth  of  the  phosphorus  having  been  lost. 

Wheat  bran  contains  about  24  pounds  of  phosphorus  per  ton, 
so  that,  for  every  100  pounds  of  bran  used  in  the  ration,  nearly 
one  pound  of  additional  phosphorus  will  be  found  in  the  manure. 
This  illustration  and  reference  to  the  average  composition  of  food 
stuffs  will  show  how  important  the  factor  of  food  is  in  affecting 
the  quality  of  manure. 

Most  analyses  of  manure  represent  the  product  in  a  more  or 
less  decomposed  state,  in  which  case  the  phosphorus  content  is 
likely  to  be  appreciably  higher  than  in  strictly  fresh  manure,  and 
even  manure  commonly  called  fresh  is  likely  to  have  lost  some 
nitrogen  and  potassium  in  the  liquid  excrement.  The  following 
analyses  include  some  accepted  averages  from  the  best  authorities. 

While  these  general  averages  may  be  satisfactorily  applied  to 
large  quantities  of  mixed  manure,  or  in  estimating  the  amounts 
of  plant  food  in  repeated  applications  of  fresh  or  yard  manure, 
respectively,  they  cannot  safely  be  used  for  small  single  lots,  unless 
the  per  cent  of  dry  matter  is  determined  and  the  character  of  the 
feed  and  bedding  used  is  known. 


FARM   MANURE 


543 


TABLE  no.   COMPOSITION  OF  FRESH  MANURE 
Pounds  per  Ton 


AUTHORITY 

KIND  OF 

MANURE 

DRY 

MATTER 

NITROGEN 

PHOS- 
PHORUS 

POTASSIUM 

Wolff      

Cows 

AC.O 

68 

I  4 

66 

S.  W.  Johnson      .... 
Cornell  Station     .... 
Sir  John  Lawes    .     .     .  •  . 
Voelcker      

Cows 
Horses 
Mixed 
Mixed 

294 

659 
672 
676 

7-6 
n-5 
i4-3 

12.  0 

i-4    . 

2-4 
2.2 
2.O 

6.0 
9.6 

IO.O 

o  s 

French  data    

Mixed 

ZOO 

7.8 

1.6 

7.5 

UNIFORM  BASIS 


Wolff      

Cows 

zoo 

7-6 

1.6 

7.3 

S.  W.  Johnson      .... 
Cornell  Station     .... 
Sir  John  Lawes    .... 
Voelcker      

Cows 
Horses 
Mixed 
Mixed 

500 
500 
500 

ZOO 

12.7 

8.7 
10.7 
0.7 

2-4 

1.9 
i-7 

2.2 

9.0 

7-3 
7-5 

7  I 

French  data     

Mixed 

500 

7.8 

1.6 

7-5 

General  average     .... 

<oo 

ox 

I.Q 

7-6 

COMPOSITION  OF  EXPOSED  YARD  MANURE 
Pounds  per  Ton 


Mass.  Station  

Average 

CCA 

8.8 

3.1 

O.4 

U.  S.  Dept.  Agr  
Voelcker      

Average 
Average 

Zoo 

9.8 

12.  1 

2.8 
•2.A. 

7-i 

7.4 

Storer     

Average 

C28 

IO.2 

2.O 

8.8 

German  data   

Average 

420 

II.  6 

2.6 

8.3 

French  data     

Average 

too 

IO.O 

2."? 

8.8 

General  average     .... 

=CO2 

10.4 

2.0 

8.3 

A  ton  of  manure  carrying  60  per  cent  of  water  contains  twice  as 
much  plant  food  as  the  same  manure  carrying  80  per  cent  of  water. 
This  means  that,  with  manure  carrying  80  per  cent  of  water,  by 
allowing  sufficient  of  the  water  to  evaporate,  the  content  of  dry 
matter  and  plant  food  is  doubled.  Or,  in  case  of  manure  containing 
85  per  cent  of  water,  it  is  only  necessary  to  reduce  the  water  to 
70  per  cent  in  order  to  double  its  percentage  composition  in  every 
valuable  constituent. 


544  VARIOUS   FERTILITY   FACTORS 

Sheep  manure  is  commonly  regarded  as  a  rich  manure,  but  this 
is  largely  due  to  the  fact  that  sheep  manure  is  usually  much  dryer 
than  that  from  other  kinds  of  stock.  Thus,  the  Massachusetts 
Experiment  Station  reports  the  average  of  four  analyses  of  sheep 
manure,  showing  28.4  pounds  of  nitrogen,  8  pounds  of  phosphorus, 
and  19.4  pounds  of  potassium,  per  ton;  but  this  manure  contained 
only  29.22  per  cent  of  water.  If  the -water  content  were  increased 
to  75  per  cent,  which  is  about  the  average  for.  mixed  manures,  then 
this  sheep  manure  would  contain  only  10  pounds  of  nitrogen,  2.8 
pounds  of  phosphorus,  and  7  pounds  of  potassium,  per  ton. 

By  referring  to  the  Pennsylvania  experiments  recorded  in  Table 
31,  it  will  be  seen  that  of  the  37.68  pounds  of  potassium  in  the  food 
consumed,  only  5.93  pounds  were  recovered  in  the  dung,  and  28.38 
pounds  in  the  urine.  If  these  mixed  excrements  were  exposed,  and 
the  urine  quickly  replaced  by  rain  water,  the  potassium  contained 
in  one  ton  would  decrease  from  about  8  pounds  to  2  or  3  pounds. 
(See  Table  112.) 

The  results  of  79  analyses  of  various  farm  manures,  made  from 
different  kinds  of  feed  and  bedding,  containing  varying  amounts 
of  water,  and  in  different  conditions  of  preservation  or  exposure, 
showed  a  range  per  ton  of  manure  as  follows:  Nitrogen  from  4.2 
to  27.2  pounds,  phosphorus  from  .9  to  6.5  pounds,  and  potassium 
from  2.2  to  23.2  pounds. 

At  different  places  in  the  central  West  sheep  are  shipped  in 
from  the  Western  range  and  kept  upon  full  feed  for  a  few  months. 
Several  plants  have  been  installed  for  drying  and  pulverizing  the 
sheep  manure  thus  accumulated.  Because  of  the  large  proportion 
of  grain  and  other  concentrates  in  the  rations,  the  manure  produced 
is  about  twice  as  rich  in  phosphorus  as  ordinary  manure;  but 
otherwise  the  dried  sheep  manure  has  about  the  same  composition 
as  average  fresh  manure  reduced  to  the  dry  basis,  as  will  be  seen 
from  Tables  no  and  in. 

The  value  of  dried  sheep  manure  is  best  determined  by  direct 
comparison  with  ordinary  manure,  one  ton  of  the  former  being 
worth  about  as  much  as  four  or  five  tons  of  average  fresh  manure. 
Probably  the  Pennsylvania  data  reported  in  Table  78  furnish  the 
best  information  the  world  affords  as  to  the  agricultural  value  of 
ordinary  manure  when  used  on  ordinary  soils  for  the  production 


FARM   MANURE 


545 


TABLE  in.   COMPOSITION  OF  PULVERIZED.  DRIED  MANURES 
Pounds  per  Ton 


KIND  OF  MANURE 

PLACE 

TOTAL 
NITRO- 
GEN 

TOTAL 
PHOS- 
PHORUS 

SOLUBLE 
POTAS- 
SIUM 

Dried  sheep  manure   . 
Dried  sheep  manure  .     . 
Dried  sheep  manure  .     . 
Dried  sheep  manure  .     . 
Dried  sheep  manure   .     . 

Elgin,  Illinois  (1906) 
Aurora,  Illinois  (1906) 
Aurora,  Illinois  (1908) 
Chicago,  Illinois  (1906) 
Chicago,  Illinois  (1907) 

43 
Si 
5° 
47 
44 

16 
18 
18 

15 
8 

2O 
31 
23 
37 
24 

Dried  cattle  manure    .     . 
Dried  manure    .... 

Chicago,  Illinois  (1907) 
Chicago,  Illinois  (1908) 

40 
35  ' 

6 
16 

19 
31 

of  ordinary  crops  grown  in  a  good  rotation,  and  figured  at  average 
prices  for  the  corn  belt.  These  data  give  the  manure  a  value  of 
$1.65  per  ton  where  12  tons  per  acre  are  used,  $1.32  where  16  tons 
are  applied,  and  $1.14  where  20  tons  are  applied,  for  each  four-year 
rotation,  corresponding  to  annual  applications  of  3,  4,  and  5  tons 
per  acre,  respectively.  Since  the  lightest  application  appears  to 
maintain  the  (moderate)  productive  power  of  the  land  for  the 
second  1 2-year  period  as  compared  with  the  average  of  the  first 
12  years,  it  seems  that  $1.65  per  ton  may  be  regarded  as  the  full 
agricultural  value  of  the  manure  for  use  in  permanent  systems. 

Of  course  the  manure  might  be  worth  less  on  better  land  and 
more  on  poorer  land;  and  with  different  crops  (as  cotton,  fruit, 
potatoes,  etc.).  or  with  different  prices,  its  value  would  be 
different. 

If  we  refer  our  comparison  to  the  unfertilized  land  during  the  1 2- 
year  periods,  the  12  tons  of  manure  were  worth  $1.14  a  ton  during 
the  first  12  years  and  $2. 14  a  ton  as  an  average  of  the  second  period, 
and  during  a  third  1 2-year  period  the  value  will  no  doubt  be  still 
greater,  measured  against  the  still  further  depleted,  untreated  land. 
In  the  Ohio  experiments,  with  the  five-year  rotation  (Table  82) 
8  tons  of  manure  were  worth  $2.18  a  ton  and  16  tons  were  worth 
$1.69  a  ton;  while  in  the  three-year  rotation  the  8  tons  of  manure 
applied  for  potatoes  were  worth  $3.63  per  ton,  with  potatoes  at 
50  cents  a  bushel. 

In  the  potato  experiments  on  Hoos  field  at  Rothamsted,  94.2 


546  VARIOUS   FERTILITY   FACTORS 

tons  of  manure,  applied  at  the  annual  rate  of  15.7  tons  per  acre  for 
six  years  (1876  to  1881),  produced  1326  bushels'  increase  in  the 
potatoes  during  the  26  years  (1876  to  1901),  which  at  50  cents  a 
bushel  would  give  the  manure  a  value  of  $7.04  per  ton.  Here  the 
plant  food  applied  in  the  94.2  tons  of  manure  was  from  two  to  four 
times  that  removed  from  the  soil  in  the  1326  bushels'  increase  in 
potatoes,  and  the  subsequent  yields  of  barley  show  that  the  manure 
still  produces  some  residual  effect.  However,  the  large  amount 
applied  during  the  six  years  is  equivalent  to  3  tons  of  manure  per 
acre  per  annum  for  more  than  30  years. 

When  measured  by  crop  yields,  the  value  of  a  ton  of  manure 
increases  with  the  size  of  the  area  over  which  it  is  spread,  but  the 
yield  and  profit  per  acre  usually  increases  with  the  amount  of 
manure  applied.  Hence,  with  much  land  and  little  manure,  light 
applications  are  most  profitable;  while  with  less  land  and  much 
manure  available,  heavy  applications  bring  the  greatest  profit. 
It  should  be  remembered,  too,  that  manure  may  act  as  a  power- 
ful soil  stimulant,  when  light,  infrequent  applications  are  made  on 
good  land,  from  which  more  plant  food  is  removed  in  crops  than  is 
applied  in  the  manure. 

In  an  experiment  conducted  at  Cornell  University,  4000  pounds 
of  ordinary  manure  from  the  horse  stable,  worth  $2.74  per  ton  for 
the  plant  food  content  (at  commercial  prices)  were  exposed  in  a 
pile  out  of  doors  from  April  25  to  September  22,  but  at  the  end  of 
that  time  the  total  weight  had  decreased  to  1 770  pounds,  worth  only 
$2.34  per  ton.  In  other  words,  the  value  of  this  pile  of  manure  was 
reduced  from  $5.48  to  $2.03  during  five  months'  exposure.  In 
another  Cornell  experiment,  manure  exposed  for  six  months  lost 
56  per  cent  of  its  dry  matter  and  43  per  cent  of  its  plant-food  value. 
In  this  case  the  fresh  manure  was  worth  $2.27  a  ton,  while  the 
rotted  manure  was  worth  $3.01  a  ton  (at  commercial  prices  for 
plant  food),  but  the  total  loss  in  weight  and  plant  food  was  such 
that  for  each  ton  originally  worth  $2.27  there  remained  only  $1.30 
worth  after  six  months'  exposure. 

The  Ohio  Agricultural  Experiment  Station  placed  five  lots  of 
manure,  of  1000  pounds  each,  in  flat  piles  in  the  barnyard.  Four 
of  these  lots  of  manure  had  been  treated  with  materials,  as  indicated 
in  Table  112,  at  the  rate  of  40  pounds  per  ton  of  manure.  The 


FARM   MANURE  . 


547 


manure  was  sampled  for  analysis  when  put  out  in  January  and 
again  when  taken  up  in  April : 

TABLE  112.   COMPOSITION  OF  STEER  MANURE  BEFORE  AND  AFTER  EXPOSURE 
FOR  THREE  MONTHS  (Pounds  per  Ton  of  Fresh  Manure) 


TREATMENT 

TIME 

OR- 
GANIC 
MATTER 

NITROGEN 

PHOSPHORUS 

POTASSIUM 

Total 

Water- 
soluble 

Total 

Water- 
soluble 

Total 

Water- 
soluble 

Raw  phosphate 

January 
April 
%  loss 

349.00 

3J°-74 
10.96 

10.70 
7.46 
30.28 

4.28 
1.  06 

75-23 

8.60 

7-57 
11.97 

1.52 
1.32 
13.16 

7.38 
3-52 
52.30 

6.58 

3-47 

47.26 

Acid  phosphate 

January 
April 
%  loss 

357-80 
269.89 
24-57 

9.86 
7.l8 
27.18 

3-°4 
.84 
72.36 

5-7o 

4-79 
15.96 

2.28 
I-5I 

33-77 

6.88 

2-99 

56.54 

6.88 
2.51 
63-51 

Kainit  .     .     . 

January 
April 
%  loss 

369.00 
291.50 
2I.OO 

9.76 

6.68 
3i-56 

3-14 

•3i 
90.12 

2.88 
2.48 
13.89 

1.36 

i-3i 

3-68 

10.70 
4.98 
53-46 

10.66 
4.96 

53-47 

Gypsum    .     . 

January 
April 
%  loss 

375-40 

267.35 
28.78 

9.68 

7-94 
17.97 

2.12 
1.46 
3I-I3 

2.76 
2.66 
3-63 

.78 

•75 
3-85 

7.86 
2.56 
67.42 

7.86 

2-49 
68.32 

None    .     .     . 

January 
April 
%  loss 

4l6.OO 
254-79 
38.75 

10.30 
7.18 
30.29 

3-36 
I.I4 
66.07 

3-24 
2.47 
23.76 

1.66 
1.26 

24.10 

8.14 

3-35 
58.84 

8.14 
2.84 
65.11 

Average  per  cent  loss    . 

24.81 

27.46 

66.98 

13.84 

i5-7o 

57-7i 

59-53 

The  results  show  that  practically  all  of  the  potassium  is  water- 
soluble,  and  that  more  than  half  of  this  and  two  thirds  of  the  water- 
soluble  nitrogen  was  lost  during  three  months'  exposure  to  the 
weather  of  winter  and  early  spring  at  Wooster,  Ohio.  Gypsum 
markedly  reduced  the  solubility  of  both  nitrogen  and  phosphorus. 

Manure  should  either  be  hauled  to  the  field  and  spread  as  soon  as 
possible  after  it  is  produced,  or  it  should  be  allowed  to  accumulate 
in  the  stalls  or  covered  sheds  in  compact  and  moist  condition,  suf- 
ficient bedding  being  used  to  keep  the  animals  clean  (and  this  is 
a  more  sanitary  practice  for  a  well- ventilated  dairy  barn  than  to 
stir  up  the  manure  daily  to  clean  the  stable),  and  then  hauled  and 
applied  at  convenient  intervals.  In  no  case  should  it  be  allowed 
to  heat  and  ferment  before  being  spread  on  the  land,  if  its  full 
value  is  to  be  secured. 


548  VARIOUS   FERTILITY   FACTORS 

Manure  may  be  applied  on  pastures  at  almost  any  time  of  year 
with  marked  benefit  to  the  grass  and  with  additional  benefit  after 
being  plowed  under  for  succeeding  crops.  It  may  be  applied  for 
corn  either  before  or  after  the  ground  is  plowed,  although  very 
coarse  manure  applied  after  plowing  may  interfere  with  cultiva- 
tion. Used  as  a  top  dressing  for  winter  wheat,  even  very  coarse 
manure  gives  good  results  if  uniformly  distributed. 

Coarse  manure  or  heavy  applications  of  fresh  manure  plowed 
under  late  in  the  spring  are  likely  to  give  unsatisfactory  results 
in  a  dry  season,  in  part  because  the  layer  of  manure  tends  to  inter- 
fere with  the  capillary  connection  of  the  soil  and  subsoil  and  retards 
upward  movement  of  the  soil  moisture  in  dry  weather.  Thorough 
disking  just  before  plowing  will  help  to  avoid  this  trouble,  whether 
farm  manure  or  green  manure  (as  a  heavy  growth  of  clover)  is 
to  be  plowed  under. 

In  the  author's  opinion,  the  crop  rotation  in  live-stock  farming 
should  be  so  planned  that  there  is  always  a  place  to  haul  and 
spread  manure,  and  so  that  every  cultivated  field  is  covered  with 
manure  at  least  once  during  each  rotation,  the  manure  being 
spread  lightly  or  heavily  in  accordance  with  the  annual  supply 
and  the  size  of  the  field  to  be  covered;  and,  if  necessary,  in  order 
to  maintain  the  humus  and  nitrogen  content  of  the  soil,  the  farm 
manure  should  be  supplemented  by  plowing  under  clover  or  other 
legumes,  keeping  in  mind  that  one  ton  of  clover  hay  plowed  under 
is  equivalent  to  four  tons  of  average  fresh  manure,  and  that  many 
can  grow  clover  who  cannot  produce  sufficient  manure. 


CHAPTER  XXXI 

LOSSES  OF  PLANT  FOOD  FROM  PLANTS 

To  determine  the  amounts  of  the  different  elements  required 
for  the  production  of  crops,  analyses  have  commonly  been 
made  of  the  mature  plants,  but  there  is  much  evidence  that  the 
results  thus  secured  may  not  always  represent  the  full  amounts 
positively  required  for  the  growth  of  the  crop  produced.  The 
ultimate  purpose  of  every  plant  (if  we  may  so  speak)  is  repro- 
duction; and  in  the  main  it  is  the  function  of  the  leaves  and  stem 
to  contribute  toward  the  formation  of  seed.  The  fixation  of  carbon, 
oxygen,  and  hydrogen  occurs  only  in  the  leaves  or  other  green 
parts  of  the  plants,  and  the  carbohydrates  thus  formed  by  photo- 
synthesis, as  well  as  the  proteids,  are  in  considerable  part  trans- 
ported to,  and  stored  in,  the  seed.  The  leaf  is  well  called  the 
laboratory  of  the  plant,  but  in  the  workshop  or  factory  certain 
tools  are  necessary,  including  potassium,  magnesium,  calcium,  and 
iron,  besides  the  nitrogen,  phosphorus,  and  sulfur  which  are'formed 
into  living  tissue  in  connection  with  the  carbon,  oxygen,  and 
hydrogen.  But  these  four  elements  (potassium,  magnesium,  cal- 
cium, and  iron),  which  we  may  perhaps  call  work  tools  rather  than 
structural  materials,  are  in  large  part  discarded  after  some  use,  and 
they  are  found  deposited  to  some  extent  in  the  old  leaves  which 
may  become  dead  or  inactive  before  the  growth  of  the  plant  is 
complete  and  while  growth  is  still  very  active  in  the  newer  leaves 
and  other  younger  parts  of  the  plant. 

As  the  older  leaves  become  inactive,  more  or  less  of  the  plant 
food  which  they  contained  and  required  for  their  own  growth  is 
translocated  to  the  newer  leaves,  but  very  considerable  amounts 
may  be  removed  by  leaching  and  thus  returned  to  the  soil  by  an 
external  route.  As  the  plant  approaches  maturity,  appreciable 
amounts  of  plant  food  are  thus  removed  by  being  washed  or  leached 

549 


550 


VARIOUS   FERTILITY   FACTORS 


from  the  leaves  by  rain  water.  It  is  not  only  possible,  but  even 
probable,  that  under  some  conditions  the  same  plant  food  may  be 
used  twice  by  the  same  plant;  that  is,  it  may  serve  an  essential 
need  in  the  growth  of  the  first  leaves,  then  be  leached  out  and  car- 
ried back  into  the  soil,  and  finally  be  reabsorbed  through  the  roots 
and  serve  the  plant  again  in  the  newer  leaves.  While  this  double 
use  is  probably  insignificant,  the  point  of  special  importance  is 
that  the  analysis  of  the  mature  plant  may  not  find  all  of  the  plant 
food  which  has  been  absolutely  essential  for  the  growth  of  the 
plant,  as  will  be  seen  from  the  tabular  statements. 

Many  years  ago  the  Rothamsted  Experiment  Station  harvested 
a  bean  crop  from  different  parts  of  a  uniform  field  at  six  different 
stages  of  growth  or  development,  from  May  26  to  September  8, 
and  for  each  period  the  crop  harvested  was  weighed  and  analyzed, 
with  the  results  indicated : 

TABLE  113.   COMPOSITION  OF  THE  BEAN  CROP  AT  DIFFERENT  PERIODS  OF 

GROWTH  (ROTHAMSTED  INVESTIGATIONS) 

Pounds  per  Acre 


DATE  OF  HARVEST  .... 

MAY  26 

JUNE  17 

JULY  8 

JULY  27 

AUG.  30 

SEPT.  8 

Condition  of  Plants  .... 

Before 
Blooming 

In  Bloom 

Bloom  off 
at  Bottom 
but  still 
on  at  Top 

In  Pod 

Green 
Pod  be- 
ginning 
to  Turn 

Seed 
fairly 
Ripe 

Dry  matter       .... 
Nitrogen      

294.0 
13.  1 

960.0 
11.2 

2481.0 
72  2 

4245.0 
114  2 

4192.0 
IIQ  Q 

4500.0 

129  6 

Phosphorus      .... 
Potassium    

1.2 

9? 

3-1 

2d  2 

6.9 

en  7 

9-5 
664 

II.  2 

57  i 

11.7 
56  o 

Magnesium      .... 
Calcium       

.6 

4.1 

1.6 

IO  Q 

3-8 

27  6 

5-5 

AC   Q 

4.8 
35.6 

5-2 
31.  1 

Sulfur      

,-j 

I  i 

2  I 

-2    2 

*jj 

7.1 

•3.4 

Sodium   

I  i 

•7   A 

6  q 

64 

C  2 

Chlorin   

i  6 

•l  2 

6  i 

76 

6  i 

6.< 

Total  ash     

•}•}  o 

88.4 

106.3 

28l.9 

230.2 

223.1 

It  will  be  noted  that  the  dry  matter,  nitrogen,  phosphorus,  and 
sulfur  all  continue  to  increase  until  the  full  maturity  of  the  plant, 
the  slight  apparent  decrease  for  dry  matter  and  sulfur  in  the  crop 


LOSSES    OF   PLANT   FOOD   FROM   PLANTS        551 

of  August  30  probably  being  due  to  variation  in  yield  of  the  plots 
harvested.  Concerning  this  investigation,  Lawes  and  Gilbert 
made  the  following  statements: 

"It  might  be  supposed  that  there  was  some  error  in  these  estimates  of  the 
amounts  of  the  crop  and  of  its  constituents  over  a  given  area,  and  they  ad- 
mittedly involve  some  difficulty  and  uncertainty;  as,  for  example,  the  possi- 
bility of  loss  by  fallen  leaves,  etc.  But  the  fact  that  the  phosphoric  acid,  which 
would  probably  for  the  most  part  exist  in  a  less  soluble  and  less  migratory 
condition,  is  shown  by  the  figures  to  increase  gradually  in  amount  per  acre  from 
the  first  period  to  the  last,  tends  to  confirm  the  contrary  results  relating  to  the 
lime  and  potash;  and,  assuming  them  to  be  correct,  the  supposition  is  that  a 
quantity  of  surplus  lime  and  potash  had  been  accumulated  in,  or  excreted  by, 
the  roots." 

There  is  no  evidence  to  substantiate  the  "supposition"  that 
potassium  and  calcium  are  excreted  by  the  roots  or  that  they 
tend  to  leave  the  tops  and  accumulate  in  the  roots,  but  there  is  now 
complete  proof  of  loss  by  leaching. 

While  these  results  obtained  by  Lawes  and  Gilbert  many  years 
ago  show  losses  only  of  elements  which  are  not  constituent  parts 
of  the  living  tissue  or  structure  of  the  plant,  it  should  be  kept  in 
mind  that  phosphorus  may  have  been  the  limiting  element,  and 
that  the  bean  plant  probably  took  up  through  its  symbiotic  rela- 
tionship with  the  nitrogen-fixing  bacteria  no  more  nitrogen  than 
was  needed  for  the  normal  growth  of  the  plant;  also  that  where 
an  excess  of  available  nitrogen  or  phosphorus  is  furnished  by  the 
soil,  any  growing  plant  may  take  up  and  tolerate  more  than  it  can 
use  in  tissue  building  (because  of  some  other  limiting  factor)  and 
that  such  excess  of  any  element  beyond  the  needs  of  the  plant 
may  perhaps  be  removed  in  the  process  of  leaching  by  rains. 

An  investigation  by  Wilfarth,  Romer,  and  Wimmer  was  reported 
in  1905  (Landwirtschaftlichen  Versuchs-Stationeri),  in  which  bar- 
ley, wheat,  and  potatoes  were  harvested  at  different  periods  of 
growth  and  both  the  tops  and  roots  were  analyzed.  The  results 
for  barley  are  shown  in  Table  114. 

From  these  experiments  it  will  be  seen  that  the  dry  matter  and 
phosphorus  reached  their  maxima  in  the  third  harvest  and  declined 
but  slightly  thereafter;  whereas  the  largest  amounts  of  nitrogen  and 
potassium  were  found  at  the  time  of  the  second  harvest  (June  17) 


552 


VARIOUS   FERTILITY   FACTORS 


TABLE  114.   COMPOSITION  OF  BARLEY  AT  DIFFERENT  PERIODS  OF  GROWTH: 

KILOGRAMS  PER  HECTAR  l  (roughly,  Pounds  per  Acre) 

(Wilfarth,  Romer,  and  Wimmer) 


HARVEST 

STRAW 

GRAIN 

TOTAL 
CROP 

ROOTS 

ROOTS 

AND 

STUBBLE 

TOTAL 
PLANT 

RELATIVE 
AMOUNTS 

No. 

Date 

Total 
Crop 

Total 
Plant 

DRY  MATTER 


I 

May  29 

2025 

2025 

45o 

799 

2824 

23 

29 

2 

June  17 

5167 

337 

55!° 

322 

i367 

6871 

63 

72 

3 

July  3 

6986 

1773 

8760 

250 

759 

95i8 

99 

IOO 

4 

July  27 

5695 

3108 

8810 

in 

476 

9279 

IOO 

97 

NITROGEN 


I 

May  29 

48.1 

48.1 

5-9 

9-2 

57-3 

/i 

66 

2 

June  17 

60.  i 

7-4 

67,S 

3-6 

I9.O 

86.5 

IOO 

IOO 

3 

Jul7     3 

40.0 

26.6 

66.6 

2.2 

4.6 

71.2 

99 

82 

4 

July  27 

17.1 

44.1 

61.2 

I.I 

3-2 

64.4 

9i 

75 

PHOSPHORUS 


I 

May  29 

7-5 

7-5 

.8 

1.8 

9-3 

42 

49 

2 

June  17 

12.7 

i-5 

14.2 

•7 

3-7 

17.9 

81 

94 

3 

July   3 

10.8 

7.0 

17.8 

-4 

1.4 

19.2 

IOO 

IOO 

4 

July  27 

4.2 

13.0 

17.2 

.1 

.6 

17.8 

97 

.    93 

POTASSIUM 


I 

May  29 

58.9 

59-1 

2-3 

9.6 

20.7 

6! 

58 

2 

June  17 

92.0 

4-9 

96.9 

2-3 

21.8 

118.7 

IOO 

IOO 

3 

July   3 

79-3 

14.1 

93-4 

i-3 

6.6 

IOO.O 

96 

84 

4 

July  27 

54-9 

19.1 

74.0 

•4 

3-1 

77.1 

76 

65 

1  The  hectar  contains  10,000  square  meters  (the  meter  being  39.37  inches), 
or  2.471  acres,  and  the  kilogram  contains  2.2046  pounds;  so  that  i  pound  per  acre 
is  equivalent  to  1.12  kilograms  per  hectar.  Thus,  for  practical  accuracy,  deduct 
one  tenth  to  convert  kilograms  per  hectar  to  pounds  per  acre. 

and  afterward  decreased  to  75  and  65    per    cent,  respectively, 
of  the  maxima.    It  is  noteworthy  that  the  barley  crop,  which 


LOSSES    OF   PLANT   FOOD    FROM   PLANTS 


553 


finally  yielded  four  tons  of  dry  matter  per  acre,  contained  87 
pounds  of  potassium  on  June  17,  but  only  66.6  pounds  at  maturity. 
The  total  plant,  including  the  roots  and  stubble,  contained  106.8 
pounds  per  acre  of  potassium  on  June  17,  but  only  69.4  pounds  at 
maturity  (July  27). 

Wilfarth,    Romer   and    Wimmer's    investigations  with    spring 
wheat  showed  the  following  results: 

RELATIVE  AMOUNTS  OF  PLANT  FOOD  IN  WHEAT  CROPS 


HARVEST 

DRY  MATTER 

NITROGEN 

PHOSPHORUS 

POTASSIUM 

No. 

Date 

Total 
Crop 

Total 
Plant 

Total 
Crop 

Total 
Plant 

Total 
Crop 

Total 
Plant 

Total 
Crop 

Total 
Plant 

I 

June  22 

25 

28 

70 

70 

43 

46 

70 

72 

2 

July  14 

69 

74 

75 

76 

72 

75 

IOO 

IOO 

3 

Aug.    5 

95 

97 

IOO 

IOO 

98 

IOO 

99 

99 

4 

Aug   28 

IOO 

IOO 

82 

81 

IOO 

99 

59 

59 

In  the  case  of  potatoes,  the  tops  at  maturity  contained  only  24 
per  cent  of  the  maximum  dry  matter,  the  corresponding  percent- 
ages being  43  for  nitrogen,  39  for  phosphorus,  and  13  for  potas- 
sium; but  in  the  tubers  the  maxima  for  all  constituents  were 
found  at  maturity. 

After  discussing  different  suggestions,  Wilfarth,  Romer,  and 
Wimmer  state  that  the  only  possible  assumption  for  the  loss  of  po- 
tassium from  the  barley  plants  is  that  it  returns  to  the  soil  through 
the  roots  ("durch  die  Wurzeln  in  den  Boden  zuriickzuwandern"). 

In  a  letter  dated  March  13,  1908,  the  author  expressed  the 
following  opinion  to  his  colleague,  Professor  J.  H.  Pettit,  then 
at  the  University  of  Gottingen: 

"I  do  not  believe  the  return  is  by  the  internal  route  through  the  stem  and 
root,  but  by  leaching,  even  before  the  plants  are  sufficiently  mature  to  harvest."1 

1  This  opinion  was  based  largely  upon  experience  in  the  preparation  of  phar- 
maceutical infusions  and  upon  field  observations,  as  where  corn  on  peaty  swamp 
land  shows  markedly  the  effect  of  potassium  leached  from  an  oat  shock  which 
stood  through  one  or  two  heavy  rains  the  previous  season.  In  the  letter  to  Professor 
Pettit  mentioned  above,  a  complete  outline  was  given  for  a  laboratory  and  pot- 
culture  experiment  to  secure  more  exact  data  upon  the  problem,  but  subsequently 
reported  investigations  render  this  unnecessary. 


554  VARIOUS   FERTILITY   FACTORS 

In  October,  1908,  Max  Wagner  reported  1  a  similar  very  ex- 
tended investigation  with  barley,  oats,  mustard,  and  buckwheat, 
with  various  systems  of  fertilizing.  With  the  barley  and  oats 
more  or  less  loss  of  plant  food  occurred  before  the  crops  reached 
maturity,  but  in  most  cases  phosphorus  proved  an  exception  to 
the  rule  wherever  the  crops  were  grown  without  the  addition  of 
a  phosphorus  fertilizer. 

After  suggesting  and  rejecting  the  possibility  of  explaining  the 
loss  of  plant  food  (a)  by  loss  of  leaves  or  roots  in  harvesting  the 
plants,  (b)  by  the  decay  of  root  parts,  and  (c)  by  volatilization 
(except  for  nitrogen) ,  Wagner  concludes  that  the  only  possible  ex- 
planation is  "  that  during  the  ripening  processes  of  the  plant,  a  part 
of  the  nutrient  materials  passes  into  the  roots  and  from  the  roots 
out  into  the  soil."  ("Fur  Kali  und  Phosphorsaure,  die  ja  durch 
Veratmung  nicht  verloren  gehen  konnen  bleibt  nur  dieMoglichkeit 
iibrig,  dass  ein  Teil  dieser  Nahrstoffe  wahrend  des  Reifeprozesses 
der  Pflanzen  in  die  Wurzel  zuriickgewandert  und  aus  den  Wurzeln 
zuriick  in  den  Kulturboden  getreten  ist.") 

In  studying  the  composition  of  solutions  used  for  spraying, 
Le  Clerc  and  Breazeale  of  the  United  States  Bureau  of  Plant 
Industry  found  material  in  the  liquid  other  than  that  put  in  the 
prepared  solution,  and  upon  further  investigation  they  deter- 
mined with  certainty  that  relatively  large  quantities  of  essential 
plant-food  elements  may  be  removed  from  growing  plants  by 
spraying  with  pure  water,  by  a  process  similar  to  the  action  of 
falling  rain. 

On  November  18,  1908,  a  summary  of  these  experiments  was 
presented  to  the  Washington  meeting  of  the  American  Society  of 
Agronomy,  by  Doctor  Le  Clerc.  By  collecting  and  analyzing  the 
water  used  for  spraying  the  plants  and  analyzing  the  fully  mature 
plants,  it  was  found  that  of  the  total  amounts  contained  in  the 
plants,  the  following  percentages  were  leached  out  by  pure  water 
(according  to  the  author's  unverified  notes,  taken  during  Doctor 
Le  Clerc's  lecture) : 

In  these  experiments  nitrogen  appears  to  have  been  the  limiting 
element  in  plant  growth,  since  practically  all  that  was  taken  up 
of  that  element  was  evidently  required  in  the  plant  structure, 

1  Die  Land-wins chafttichen  Versuchs-Stationen  (1908)  69,  161-233. 


LOSSES   OF   PLANT   FOOD   FROM   PLANTS        555 


TABLE  115.   PLANT  FOOD  REMOVED  FROM  PLANTS  BY  LEACHING  WITH  WATER 
Percentage  of  Total 


PLANTS  LEACHED 

NI- 
TRO- 
GEN 

PHOS- 
PHO- 
RUS 

PO- 
TAS- 
SIUM 

MAG- 
NESI- 
UM 

CAL- 
CIUM 

SO- 
DIUM 

CHLO- 

RIN 

Wheat,  in  early  bloom    

I 

o 

A 

IO 

o 

12 

Wheat,  fairly  ripe       

7 

•37 

54. 

16 

34 

41 

6n 

Wheat,  dead  ripe  

25 

21 

65 

58 

55 

56 

QO 

Oats,  from  8  inches  in  height  to  ripeness; 
total  removed  by  repeated  leaching  . 

2 

33 

36 

45 

40 

23 

40 

Potato  vines      . 

7 

CQ 

20 

12 

n 

TT> 

5O 

and  could  not  be  removed  by  leaching,  except  in  the  case  of  the 
dead-ripe  wheat;  while  phosphorus  as  well  as  the  other  elements 
was  apparently  taken  up  in  excess  of  the  absolute  needs  of  the 
plants  and  in  part  tolerated  until  removed  by  leaching.  This  is 
the  most  probable  explanation  for  the  difference  in  results  from 
these  experiments  and  those  reported  by  Wilfarth,  Romer,  and 
Wimmer;  and  the  author  has  taken  the  liberty  of  suggesting  to 
Le  Clerc  and  Breazeale  that  by  extending  these  investigations  in 
connection  with  fertilizer  experiments,  results  of  great  scientific 
value  and  of  far-reaching  practical  importance  will  probably  be 
secured  in  relation  to  the  absolute  requirements  of  plants  for  the 
different  elements  essential  to  plant  growth.  It  has  long  been 
recognized  that  the  analysis  of  the  plant  or  of  the  plant  ash  was 
not  a  sufficient  guide  for  use  in  planning  systems  of  fertilization; 
but,  for  certain  of  the  elements,  the  analysis  of  the  thoroughly 
leached  plant  at  the  proper  stage  of  growth  may  give  more  satis- 
factory information;  and,  because  of  its  very  general  character, 
it  seems  especially  appropriate  that  it  should  be  continued  by 
the  federal  government,  while  local  problems,  such  as  county  soil 
surveys,  are  perhaps  better  managed  by  the  state  institutions. 

The  fact  that  phosphorus  is  most  frequently  the  limiting  element 
in  plant  growth  or  crop  yield  on  most  normal  soils,  especially  for 
legume  crops,  suggests  that  the  averages  commonly  accepted  for 
the  composition  of  crops  probably  represent  the  minimum  amounts 
of  phosphorus,  as  a  rule. 


CHAPTER  XXXII 

LOSSES  OF  PLANT  FOOD  FROM   SOILS 

THERE  .  are  four  ways  in  which  plant  food  may  be  lost  or  re- 
moved from  the  soil:  (i)  by  removal  in  crops  as  already  explained, 
(2)  by  leaching  after  solution  in  the  rain  water  or  soil  water,  (3)  by 
mechanical  erosion,  either  by  surface  washing  or  by  wind  action, 
and  (4)  by  volatilization,  a  factor  of  minor  importance,  represented 
chiefly  by  the  slight  loss  of  nitrogen  in  ammonia  or  by  denitri- 
fication,  a  process  which  may  occur  to  a  limited  extent  under  some- 
what abnormal  conditions. 

Loss  of  plant  food  from  soils  by  the  process  of  leaching  is  a  matter 
of  very  great  consequence,  chiefly  because  large  amounts  of  nitrogen 
may  thus  be  lost  every  year  in  humid  sections.  Even  under  the 
best  systems  of  farming  more  or  less  nitrogen  is  likely  to  pass  off 
in  drainage  waters.  The  annual  loss  of  lime  by  leaching  is  large 
(see  Tables  27  and  28),  and  when  long  periods  of  time  are  con- 
sidered, the  amounts  of  magnesium,  potassium,  and  other  elements 
removed  from  the  soil  by  leaching  (see  Table  74)  become  very 
significant. 

The  only  practical  method  of  preventing  or  reducing  the  loss  by 
leaching  is  by  the  use  of  growing  plants,  the  roots  of  which  may 
absorb  the  plant  food  about  as  rapidly  as  it  is  made  soluble.  If 
desired,  it  may  be  then  returned  to  the  soil  in  the  form  of  organic 
matter,  afterward  to  become  available  when  required  to  meet  the 
needs  of  regular  crops.  The  use  of  rye  or  rape  as  a  green  manure, 
by  seeding  in  the  fall  and  plowing  under  the  next  spring  on  land  that 
would  otherwise  lie  bare  during  the  fall,  winter,  and  early  spring, 
is  often  profitable,  in  part  because  of  the  conservation  of  plant 
food  that  would  otherwise  be  lost  by  leaching.  This  fact  and 
principle  is  well  illustrated  by  the  following  data  from  that  great 
source  of  positive  agricultural  information,  the  Rothamsted  Ex- 
periment Station. 

SS6 


LOSSES    OF   PLANT   FOOD   FROM   SOILS 


557 


TABLE  116.   NITROGEN  IN  DRAINAGE  WATERS:   ROTHAMSTED  EXPERIMENTS 
Average  of  12  Years  (or  More) 


MONTH 

RAINFALL 
(Inches) 

BARE  SOIL,  6o-lNCH  GAUGE 

WHEAT 
LAND, 
NITROGEN 
(Per  Mil- 
lion of 
Water) 

Drainage 
(Inches) 

Nitrogen 
(Per  Million 
of  Water) 

Nitrogen 
(Pounds 
per  Acre) 

January       

2.13 
2.l6 
1.70 
2.25 

1-93 
1.74 

•94 
•79 

8.9 
9.I 
8.9 
9.0 

3.88 

3-57 
1.89 
1.61 

3-1 
4.0 
2.0 
1.9 

February     

March    

April       

May  

2.48 

2-59 
2.85 
2.69 

•79 
.78 
.62 
.76 

9.I 
9.1 

n.8 
J3-3 

1.63 
i.  60 
1.66 

2.28 

•9    • 
.1 
.1 
.1 

June       

My  . 

August   

September  
October       
November  .     .     . 

2.70 
3.12 
3.20 

2-34 

.82 
1.68 

2.32 
1.88 

13-4 
11.9 
11.4 
10.6 

2.50 

4-53 
5-98 
4-51 

3-9 
4.6 

3-6 

4.8 

December  

January-April      .... 
Mav-August    

8.24 
10.61 
11.36 

5-4° 

2-95 
6.70 

9.0 
10.6 
n.8 

10.95 
7.17 
I7-52 

2.8 

•3 
4.2 

September-December   .     . 

January-December  .     .     . 

30.21 

iS-05 

10.5 

35-64 

2.4 

While  the  drainage  water  from  the  bare  uncropped  soil  of  the 
drain  gauge  contained  11.4  parts  of  nitrogen  per  million  during  the 
summer  months  (June  to  August),  the  drainage  water  from  the 
land  on  which  wheat  was  growing  (Broadbalk  plots  3  and  4)  con- 
tained only  .1  pound  of  nitrogen  per  million  pounds  of  water,  as 
an  average  of  the  three  months.  After  the  wheat  harvest,  the  loss 
of  nitrogen  in  the  field  drains  quickly  rises  to  about  4  pounds  per 
million.  In  loss  per  acre  the  differences  are  much  greater,  because 
during  the  growing  season  the  quantity  of  drainage  from  the  field 
is  probably  even  less  than  that  from  the  drainage  gauge,  and  the 
data  from  the  gauge  show  two  to  three  times  as  much  drainage 
during  the  other  months. 

In  Table  117  are  recorded  the  amounts  of  water-soluble  nitrogen 
found  in  the  soil  and  subsoil  of  Hoos  field,  where  the  shallow-rooting 
white  clover  (Trifolium  repens)  had  been  grown  for  seven  years  and 
where  the  vetch  and  the  deep-rooting  alfalfa  had  been  grown  for 


558 


VARIOUS   FERTILITY   FACTORS 


six  years,  also  of  Agdell  field  after  the  wheat  crop  had  been  har- 
vested, in  the  legume  system  and  the  fallow  system,  for  which  the 
yields  are  recorded  in  Table  57. 

TABLE  117.   SOLUBLE  NITROGEN  IN  CROPPED  SOILS  RECEIVING  NO  NITROGEN 
FERTILIZER  SINCE  1849  (Pounds  per  Acre) 


Hoos  FIELD 

AGDELL  FIELD 

Wheat  Land 

DEPTH 

White 

Alfalfa 

Vetch 

Land 

Land, 

Land, 

Julv,' 

July, 

July, 

After 

After 

1885 

1885 

1883 

Clover, 

Fallow, 

Fall,  1883 

Fall,  1883 

First  9  inches  

II.S 

8.9 

IO.2 

6.1 

3.4 

Second  9  inches    .     .     .     . 

J 
1.4 

y 
I.I 

2.7 

4.4 

O't 

2.1 

Third  9  inches      .     .     .     . 

•9 

.8 

I.I 

1.6 

.8 

Fourth  9  inches    .... 

1.9 

.8 

i-5 

i-3 

I.O 

Fifth  9  inches  

7.1 

I.O 

2.< 

i.< 

.8 

Sixth  9  inches  

/ 
II.  3 

.0 

j 
4.4 

o 
.8 

.6 

Seventh  9  inches  .... 

o 
J3-1 

V 

.6 

«t*«l 

4-5 

2.2 

.8 

Eighth  9  inches    .... 

12.6 

.8 

4-9 

i-7 

•9 

Ninth  9  inches      .... 

II.  2 

•7 

4.8 

2-4 

•7 

Tenth  9  inches     .... 

I0.y 

.6 

5-i 

2.1 

2.0 

Eleventh  9  inches      .     .     . 

II.  I 

•4 

6.4 

2.1 

i-5 

Twelfth  9  inches  .... 

IO.O 

•4 

6-5 

2.8 

3-8 

0—9  inches   

II.  1 

8.9 

IO.2 

6.1 

-J  A 

9-36  inches      

J 
4.2 

•  y 

2.7 

^  3 

7  3 

O'T' 

•2  Q 

?-o  feet  . 

«t*« 

87.! 

/ 
5-4 

J'j 

39-i 

I'J 

15.6 

O'V 
II.  I 

The  crops  of  white  clover  were  too  small  to  cut  in  1880,  1883,  and 
1884,  and  in  other  years  only  a  single  cutting  was  harvested. 
Thus  most  of  the  rather  small  amount  of  produce  was  left  to  decay 
upon  the  white  clover  plot.  Evidently  87.1  pounds  of  nitrate 
nitrogen  has  escaped  beyond  the  reach  of  the  white  clover  roots, 
while  almost  no  soluble  nitrogen  (5.4  pounds)  was  found  in  the 
same  stratum  (3  to  9  feet)  under  alfalfa.  The  root  system  of  vetch 
is  perhaps  even  less  extensive  than  that  of  white  clover  (see  Table 
36),  but  the  annual  decay  of  the  roots  possibly  gives  it  the  inter- 
mediate position  in  loss  of  nitrogen  as  indicated,  although  a  different 
season  may  perhaps  have  given  quite  different  results.  The  data 


559 

from  Agdell  field  indicate  that  only  small  amounts  of  nitrogen 
escape  from  the  wheat  plant  under  the  conditions,  these  results 
being  in  harmony  with  those  reported  in  Table  116. 

On  the  University  of  Illinois  experiment  field  at  Urbana  are 
two  adjoining  plots,  one  of  which  (No.  3)  grew  corn  for  16  years, 
while  the  other  (No.  105)  was  kept  in  pasture.  In  1901  plot  3  con- 
tained 4000  pounds  of  nitrogen  and  plot  105  contained  4914 
pounds  in  2  million  of  surface  soil,  a  loss  of  about  one  fifth  of  the 
total  being  thus  indicated. 

Professor  Shutt  reports  the  nitrogen  content  of  virgin  soil  and 
adjoining  cultivated  soil  from  the  Northwest  Territory  of  Canada. 
He  says: 

"Regarding  the  cultivated  soil,  we  possess  a  complete  and  authentic  record 
of  the  cropping  and  fallowing  since  the  prairie  was  first  broken,  22  years  ago. 
It  has  borne  6  crops  of  wheat,  4  of  barley,  and  3  of  oats,  with  fallows  (9  in  all) 
between  each. 

"Both  samples  were  of  a  composite  character  and  every  precaution  taken 
to  have  them  thoroughly  representative.  It  may,  further,  be  added  that  there 
is  every  reason  to  suppose  that  the  soil  over  the  whole  area  examined  was  origi- 
nally of  an  extremely  uniform  nature;  in  other  words,  that  at  the  outset  the  ni- 
trogen content  was  practically  the  same  for  the  soils  now  designated  as  virgin 
and  cultivated,  respectively:" 

NITROGEN,  POUNDS  PER  ACRE 

Virgin  soil,  to  depth  of  8  inches 6936 

Cultivated  soil,  to  depth  of  8  inches 4736 

Difference  or  loss  due  to  cropping  and  cultural  operation  .     .     2200 

"The  results  show  that  the  cultivated  soil  is  to-day  still  very  rich,  yet  com- 
pared with  the  untouched  prairie  it  is  seen  to  have  lost  one  third,  practically,  of 
its  nitrogen.  This  is  highly  significant.  Humus  and  nitrogen  must  be  re- 
turned, either  as  manure  or  by  the  occasional  growth  of  certain  enriching  crops, 
or  fertility  will  inevitably  decline."  (Dominion  Experiment  Farms,  Report 
for  1905,  page  128.) 

Shutt  reports  3780  and  3240  pounds  of  nitrogen  in  the  virgin 
and  cultivated  soils,  respectively,  of  Grindstone  Island,  Magdalen 
Islands,  Quebec;  also  3160  and  2260  pounds  of  nitrogen  from 
virgin  and  cultivated  soils  from  Kent  County,  New  Brunswick. 
The  corresponding  figures  for  acid-soluble  phosphorus  are  2160  and 
1970  for  the  Quebec  soils,  and  2180  and  1070  for  the  New  Bruns- 


560  VARIOUS   FERTILITY   FACTORS 

wick  soils.  The  New  Brunswick  soils  are  said  to  be  representative 
of  the  district.  In  commenting  upon  the  analytical  data,  Professor 
Shutt  says : 

"Since  we  must  suppose,  from  the  information  furnished,  that  the  culti- 
vated soil  was  originally  identical,  or  practically  so,  with  the  virgin  soilt  it  is 
evident  that  great  exhaustion  of  fertility  has  taken  place,  due,  no  doubt,  to  suc- 
cessive cropping  without  any  adequate  return  of  plant  food."  (Report  for 
1899,  page  133.) 

It  is  certain  that  on  sloping  lands  a  very  considerable  part  of  the 
total  loss  of  humus,  nitrogen,  and  phosphorus  is  due  to  soil  erosion, 
although  this  is  the  minor  factor  on  nearly  level  lands.  It  should  be 
kept  in  mind  that  in  respect  to  loss  of  humus,  and  of  the  plant  food 
contained  in  humus,  sheet  washing  on  uniform  slopes  may  be  even 
more  effective  than  gullying,  and  that  it  is  extremely  important  and 
necessary  to  prevent  or  at  least  to  reduce  to  the  minimum  both 
forms  of  erosion,  the  sheet  washing  by  means  of  cover  crops,  deep 
contour  plowing,  contour  ridging,  or  terracing,  if  necessary,  and 
the  gullying  by  frequent  dams  and  by  keeping  the  draws  in  per- 
manent meadow. 

President  Van  Hise  makes  the  following  statements  regarding 
the  loss  of  phosphorus  from  Wisconsin  soils,  as  determined  by 
"  quantitative  studies  ": 

"Whitson  finds  as  the  result  of  an  average  of  nine  typical  tests  that  'the  sur- 
face 8  inches  of  virgin  soil  contains  1256  pounds  of  phosphorus  per  acre,  while 
that  of  the  cropped  fields  contains  but  792  pounds,  an  average  loss  per  acre  on 
these  cropped  fields  of  464  pounds,  or  36  per  cent  of  its  original  content.  The 
average  of  cropping  for  these  fields  has  been  54. 7  years.'  In  other  words,  during 
the  past  half  century  in  Wisconsin  one  third  of  the  original  phosphorus  of  the 
soil  has  been  lost  in  the  cropped  fields.  What  has  been  proved  for  Ohio, 
Illinois,  and  Wisconsin  and  other  states  where  tests  have  been  made  is  unques- 
tionably true  for  the  other  states  in  the  country  which  have  been  settled  for 
some  time. 

"In  what  conditions  will  the  soil  of  the  United  States  be  as  to  phosphorus 
content  fifty  years  hence  if  this  process  of  depletion  be  allowed  to  continue  un- 
checked?" (See  page  221  of  "Conservation  of  Natural  Resources,"  published 
by  the  American  Academy  of  Political  and  Social  Science,  Philadelphia,  1909.) 

It  may  be  noted  that  a  loss  of  464  pounds  of  phosphorus  in  55 
years  is  only  8^  pounds  per  annum;  and,  if  we  deduct  i\  pounds 
for  loss  in  drainage  (see  Table  74),  the  loss  by  cropping  does  not 


LOSSES    OF   PLANT   FOOD   FROM   SOILS           561 

exceed  7  pounds  per  acre,  an  amount  sufficient  only  for  a  30- 
bushel  crop  of  corn,  or  i|  tons  of  clover  hay.  It  may  be  kept 
in  mind  that,  so  long  as  the  surface  soil  contains  more  phosphorus 
than  the  subsurface,  erosion  helps  to  deplete  the  soil  of  phosphorus ; 
but  when  the  phosphorus  content  of  the  surface  becomes  reduced 
by  cropping  to  a  point  below  that  of  the  subsurface,  then  erosion 
tends  to  increase  the  phosphorus  in  the  surface  soil. 
In  regard  to  erosion,  President  Van  Hise  says: 

"It  is  plain  that  we  must  not  permit  soil  erosion  to  take  place  more  rapidly 
than  the  soil  is  manufactured  by  the  process  of  nature.  To  do  this  will  be 
ultimately  to  destroy  our  soils.  If  nature  manufactures  the  soil  at  the  rate  of 
one  inch  in  a  century,  then  the  erosion  must  not  exceed  one  inch  in  one  century." 

Of  course,  this  statement  refers  especially  to  residual  upland 
soils  and  to  the  making  of  soils  from  the  slow  disintegration  of  the 
underlying  rock.  Most  of  the  corn-belt  subsoils  include  from  20 
to  200  feet  of  loess  and  glacial  drift  above  the  bed  rock. 

The  loss  of  plant  food  by  cropping  and  leaching  is  the  most 
serious  matter  on  most  of  the  valuable  agricultural  soils. 

Lyon  and  Bizzell  (Jour.  Ind.  and  Eng.  Chem.,  Oct.,  1911)  report 
a  loss  of  ii  pounds  of  potassium,  76  of  magnesium,  and  407  of  cal- 
cium, from  uncropped  soil;  and  8  pounds  of  potassium,  31  of  mag- 
nesium, and  1 66  of  calcium,  from  cropped  soil  (average  for  corn  and 
oats),  in  drainage  water  per  acre  from  a  four-foot  stratum  of  clay 
loam  soil,  from  May  23,  1910,  to  May  i,  1911 ;  and  Bartow  (Illinois 
State  Water  Survey  Bulletin)  reports  90  analyses  of  Illinois  well 
waters  drawn  chiefly  from  glacial  sands,  gravels,  and  till,  showing, 
as  an  average,  n  pounds  of  potassium,  130  of  magnesium,  and  330 
of  calcium,  in  3  million  pounds  of  water  (see  Table  74).  These 
data  confirm  the  results  of  the  Rothamsted  investigations  (pages 
174,  175,  413),  showing  an  excessive  availability  of  magnesium  and 
especially  of  calcium ;  and  they  clearly  indicate  that  in  many  cases 
those  elements  may  be  of  much  greater  importance  for  soil  improve- 
ment than  potassium,  even  from  the  standpoint  of  plant  food 
maintenance,  and  in  addition  to  their  value  for  correcting  soil 
acidity.  (See  also  pages  105  and  633.) 


CHAPTER  XXXIII 

FIXATION    OF   PLANT   FOOD    BY    SOILS 

WHEN  soluble  plant  food  is  applied  to  the  soil,  it  is  as  a  very 
general  rule  changed  into  insoluble  forms  by  reaction  with  the  soil. 
Nitrogen  in  the  form  of  nitrate  is  an  exception  to  this  rule,  the 
only  method  of  changing  nitrate  nitrogen  to  the  insoluble  form 
being  by  the  growth  of  some  plant  which  converts  it  into  organic 
nitrogen,  as  already  explained.1 

The  fixation  of  bases  includes  not  only  the  metals,  but  also  the 
ammonium  group,  the  soluble  base  taking  the  place  of  some  other 
element  in  an  insoluble  polysilicate,  as  illustrated  in  the  following 
general  equation: 

AlxFexMgxNaxCa  (SiO3)x(H2O)x  +  2  KC1 

=  AlxFexMgxNaxK2  (SiO3)x  (H2O)X  +  CaCl2. 

This  equation  typifies  the  reaction  of  soluble  potassium  chlorid 
with  a  zeolitic  compound,  resulting  in  the  fixation  of  potassium 
and  the  liberation  of  calcium,  which  passes  off  in  the  drainage 
waters  in  combination  with  the  acid  radicle  which  formerly  carried 
the  potassium. 

Other  mineral  bases  and  even  ammonium  may  be  fixed  in  a  simi- 
lar manner,  but  the  ammonium  fixation  is  very  temporary,  because 
under  usual  conditions  nitrification  proceeds  rapidly  and  the 
ammonia  nitrogen  passes  into  soluble  nitrate  nitrogen,  a  fact  which 
is  well  illustrated  by  the  following  data  from  Rothamsted. 

The  ammonium  salts  consisted  of  equal  parts  of  the  sulfate  and 
chlorid.  Warington  makes  the  following  comments: 

"At  the  first  running  of  the  drain  pipe  (after  October  25)  sufficient  time  had 
not  elapsed  for  the  complete  decomposition  of  the  ammonium  salt  and  the 
fixation  of  the  ammonia.  Some  undecomposed  salt  of  ammonium  is  thus 

1  Even  low  forms  of  plant  life,  as  fungi  and  bacteria,  may  aid  in  this  process. 

562 


FIXATION   OF   PLANT   FOOD   BY   SOILS 


563 


TABLE  1 18.   NITROGEN  AND  CHLORIN  IN  DRAINAGE  WATER  BEFORE  AND  AFTER 

THE  APPLICATION  OF  AMMONIUM  SALTS  ON  OCTOBER  25,  1880: 

PLOT  15,  BROADBALK  FIELD 

Pounds  per  Million  of  Water 


DATE  OF  COLLECTING  DRAINAGE  WATER 

AMMONIA 

NITROGEN 

NITRATE 
NITROGEN 

CHLORIN 

October  10     

None 

8.2 

22.7 

October  27,  6.30  A.M  

Q  O 

ll.S 

146.4 

October  27,  i.oo  P.M  
October  28     

6-5 
2.i; 

12.9 
16.  7 

116.6 

QC.7 

October  29     

I.<! 

16  Q 

80.8 

November  15,  16     

None 

co.8 

<4.2 

November  ig,  26     

None 

34.6 

47-6 

December  22,  29,  30    

None 

21.7 

2T..2 

February  2,  8,  10    

None 

22.  Q 

19.4 

found  in  the  early  drainage  waters,  —  a  circumstance  which  is  very  unusual. 
That  decomposition  of  the  salt  had  already  taken  place  to  a  very  large  extent,  is 
shown,  however,  by  the  enormous  amount  of  chlorin  in  the  first  runnings,  an 
amount  far  exceeding  that  of  the  ammonia. 

"  Even  at  this  early  stage  of  the  reaction,  only  forty -eight  hours  after  the  ap- 
plication of  the  ammonia,  nitrification  has  made  a  distinct  commencement." 

While  the  ammonia  fixation  was  probably  completed  soon  after 
October  29,  the  process  of  nitrification  was  evidently  not  entirely 
completed  on  February  2-10. 

Schlosing  reports  experiments  with  114  parts  of  ammonium 
chlorid  per  million  of  soil  in  which  88.1  per  cent  of  the  ammonia 
was  nitrified  in  18  days,  and  in  another  experiment,  with  526 
parts  of  ammonium  carbonate  per  million  of  soil,  97.7  per  cent  of 
the  ammonium  was  nitrified  in  28  days. 

The  reactions  involved  in  these  fixation  processes  are  usually 
incomplete,  mass  action  being  one  of  the  controlling  factors.  Thus 
with  soil  silicates  containing  much  calcium,  magnesium,  and  so- 
dium, and  but  little  potassium,  applied  potassium  would  doubtless 
be  largely  fixed,  with  liberation  of  calcium  or  other  bases;  whereas, 
heavy  applications  of  calcium  sulfate  will  liberate  more  or  less 
potassium  from  soils  rich  in  insoluble  potassium  compounds. 


564  VARIOUS    FERTILITY   FACTORS 

The  fixation  of  soluble  phosphates  involves  a  very  different  re- 
action, which  may  be  illustrated  as  follows: 

CaH4(PO4)2  +  CaCOg  =  Ca2H2(PO4)2  +  CO2  +  H2O. 
+  CaCO8  =  Ca3(PO4)2  +  CO2  +  H2O. 


Compounds  of  iron  or  aluminum  may  take  the  place  of  the  cal- 
cium carbonate  in  the  fixation  of  phosphates. 

Thus,  we  may  apply  to  ordinary  soil  a  solution  containing  soluble 
salts  of  potassium,  ammonium,  or  phosphorus,  but  the  liquid  which 
passes  through  a  soil  stratum  three  inches  or  more  in  thickness  will 
be  found  to  contain  very  little  of  the  salts  applied.  The  chief 
value  attached  to  soluble  fertilizers  is  due  to  their  thorough  dis- 
tribution in  the  soil  before  passing  into  insoluble  forms.  If  every 
soil  grain  touched  by  the  soluble  fertilizer  becomes  coated  with  the 
insoluble  product,  it  presents  to  the  plant  roots  a  very  much 
greater  surface  than  if  the  fertilizer  is  applied  in  small  solid  par- 
ticles, as  in  ground  rock  phosphate. 


CHAPTER  XXXIV 

ANALYZING   AND   TESTING    SOILS 

WHILE  the  chemical  analysis  of  soils  requires  knowledge,  train- 
ing, and  skill,  and  while  farmers  and  other  students  of  agriculture 
cannot  all  be  analytical  chemists,  they  should  all  be  able  to  under- 
stand the  meaning  of  a  chemical  analysis  if  it  is  reported  without 
unnecessary  complications.  The  author's  experience  in  practical 
agriculture  and  close  contact  with  progressive  farmers  desiring 
to  make  practical  application  of  scientific  information  revealed  to 
him  the  fact  that  some  of  the  common  methods  of  reporting  analyses 
of  soils  and  fertilizers  are  extremely  confusing,  if  not  positively 
misleading.  Thus,  it  is  common  to  report  the  analysis  of  potassium 
chlorid  (KC1)  in  terms  of  potash  (K2O),  notwithstanding  the  fact 
that  the  material  analyzed  contains  no  oxygen.  Sulfur  in  soils  is 
usually  reported  as  sulfur  trioxid  (SO3) ,  although  the  sulfur  may 
exist  in  the  form  of  sulfid  or  as  organic  sulfur.  Still  more  confusing, 
very  misleading,  in  fact,  is  to  report  in  terms  of  calcium  oxid  (CaO) , 
or  quicklime,  all  calcium  found  in  the  soil,  even  though  it  may 
exist  only  in  acid  silicates,  and,  instead  of  the  soil  containing  any 
lime  in  any  form,  it  may  require  an  application  of  some  form  of 
lime  to  correct  the  existing  acidity. 

The  only  kind  of  lime  which  exists  in  the  soil  in  the  agricultural 
sense,  that  is,  lime  which  has  power  to  prevent  or  correct  soil 
acidity,  is  limestone,  either  ordinary  or  magnesian;  and  this  is 
sufficient  reason  why  limestone  present  should  be  reported  as  lime- 
stone; and  for  the  same  reason  soil  acidity  is  reported  in  terms  of 
limestone  required.  Instead  of  reporting  in  terms  of  percentage  and 
leaving  the  computations  to  be  made  by  every  individual  who  de- 
sires to  use  the  data,  the  analytical  results  may  be  reported  in  the 
more  simple  and  usable  form  of  pounds  per  acre  or  pounds  per  ton, 
which  are  the  common  farm  units  of  weight  and  measure.  Manures 
and  fertilizers  are  applied  in  tons  or  pounds  per  acre,  and  they  are 

565 


566  VARIOUS   FERTILITY   FACTORS 

mixed  with  the  plowed  soil.  Hence,  we  should  know  what  the 
plowed  soil  of  an  acre  contains  of  the  different  important  con- 
stituents and  the  relations  between  the  amounts  contained  in  the 
soil  and  the  amounts  applied  in  fertilizers  and  removed  in  crops. 

This  book  is  not  a  text  on  chemistry,  but  space  is  taken  in  the 
Appendix  for  a  description  of  the  details  of  soil  analysis,  such  as 
are  given  in  the  "  Soil  Fertility  Laboratory  Manual,"  which  is 
designed  to  accompany  this  text  for  use  in  schools  and  colleges. 
Every  student  of  soil  fertility,  even  though  not  a  chemist,  should 
understand  how  to  make  a  few  simple  and  very  important  tests. 

Soil  Acidity.  To  test  for  soil  acidity,  make  a  ball  of  the  fresh, 
moist  soil,  break  it  in  two,  place  a  piece  of  blue  litmus  *  paper 
between,  and  press  the  soil  firmly  together  again.  After  a  few 
minutes  examine  the  paper.  If  it  has  turned  pink  or  red,  soil 
acidity  is  indicated.  It  is  especially  important  to  test  the  sub- 
soil for  acidity  for  reasons  already  mentioned. 

To  examine  the  soil  thoroughly,  samples  should  be  tested  from 
the  surface  and  subsoil  at  several  different  places  in  the  field; 
and  the  tests  should  be  made  by  the  landowner  in  the  field  rather 
than  by  the  chemist  in  the  laboratory.  The  amount  of  acidity  is 
indicated  to  some  extent  by  the  intensity  of  color  and  the  rapidity 
with  which  it  develops.  The  litmus-paper  test2  for  soil  acidity  is  a 
long-established,  trustworthy,  and  very  useful  test.  It  can  also 
be  used  as  a  test  for  acidity  in  other  materials,  as  in  acid  phosphate 
or  in  mixed  fertilizers  which  contain  acid  phosphate.  Place  two 
or  three  spoonfuls  of  the  fertilizer  in  a  glass,  add  half  a  glass  of 
water,  stir  well,  let  settle,  and  then  insert  a  strip  of  blue  litmus 
paper,  which  will  be  quickly  reddened  by  the  acid  solution. 

A  positive  test  for  carbonates  in  the  soil  precludes  the  presence 
of  soil  acidity,  because  the  carbonates  are  easily  decomposed  by 

1  Litmus  is  an  organic  coloring  matter  which  turns  red    in  acid  solutions  and 
blue  in  alkaline.     Litmus  paper  is  made  by  moistening   paper  with  a  solution  of 
litmus,  the  paper  then  being  dried.     The    prepared  litmus    paper   ready  for  use 
can  be  obtained  at  most  drug  stores  put  up  in  packages  of  20  or  30  pieces  for  5 
cents  a  package. 

2  Cameron  has  reported  experiments  intended  to  show  that  the  litmus-paper  test 
has  little  or  no  value,  because  he  was  able  to  change  blue  litmus  red  by  contact  with 
absorbent  cotton,  the  change  being  attributed  by  him  to  absorption;  but  it  develops 
that  bleached  cotton  may  retain  sufficient  acid  used  in  the  bleaching  process  to 
produce  the  change  of  color  in  litmus. 


ANALYZING  AND   TESTING   SOILS  567 

acids  with  the  liberation  of  carbonic  acid,  which  breaks  down  into 
water  and  gas,  carbon  dioxid.  Consequently  the  carbonates,  such 
as  calcium  carbonate  and  magnesium  carbonate,  serve  as  mild 
alkalis,  in  the  presence  of  which  soil  acidity  cannot  exist. 

Carbonates.  To  test  for  carbonates  in  the  soil,  make  a  shallow 
cup  of  a  ball  of  soil  and  pour  in  a  few  drops  of  concentrated  hy- 
drochloric acid.  If  carbonates  are  present,  a  reaction  occurs  with 
the  liberation  of  carbon  dioxid  which  appears  as  gas  bubbles, 
producing  foaming,  or  effervescence : 

CaCO3  +  2HC1  =  CaCl2  +  H2O  +  CO2. 

With  much  carbonate  present  the  action  is  rapid  and  abundant, 
but  with  mere  traces  of  carbonate  in  the  soil  only  few  bubbles  will 
appear. 

The  same  test  may  be  applied  to  limestone,  marl,  etc.,  to  ascer- 
tain -if  carbonates  are  contained  in  the  material.  Most  limestones 
and  marls  will  show  some  effervescence  with  cold  concentrated 
acid,  but  some  nearly  pure  dolomitic  limestones  require  the  appli- 
cation of  heat  to  properly  develop  the  reaction. 

Five  cents'  worth  of  concentrated  hydrochloric  acid  in  a  small 
glass-stoppered  bottle  is  sufficient  for  many  tests  for  carbonates. 
Of  course,  care  must  be  taken  not  to  get  the  acid  on  the  clothing  or 
skin.  In  case  the  acid  gets  on  the  fingers,  it  should  be  washed  off, 
or  rubbed  off  with  soil,  as  soon  as  possible.  It  is  not  especially 
dangerous  to  handle,  but  will  soon  "eat"  or  "burn"  through  the 
skin  if  not  removed  or  neutralized,  which  could  be  easily  done  by 
rubbing  with  soil  containing  carbonates. 

As  in  the  case  of  acidity,  it  is  especially  important  to  test  the 
subsoil  for  carbonates;  for  an  abundance  of  carbonates  only  i  to 
3  feet  beneath  the  surface  serves  as  a  store  and  protection,  especially 
in  critical  periods  in  the  growth  of  such  plants  as  clover  and  alfalfa, 
which  may  die  during  a  few  weeks  of  summer  drouth  if  the  rising 
capillary  moisture  carries  acidity,  but  would  be  kept  alive  if  this 
moisture  brought  traces  of  calcium  bicarbonate. 

If  the  landowner  has  no  other  source  of  information  concerning 
the  composition  of  his  soil,  it  is  altogether  advisable  to  collect  a 
composite  sample  of  the  plowed  soil  (made  by  mixing  together 


568  VARIOUS   FERTILITY  FACTORS 

about  20  borings  taken  from  as  many  different  places  where  the 
soil  appears  to  be  uniform  and  truly  representative  of  the  soil  type) 
and  employ  a  skilled  chemist  to  determine  the  total  phosphorus  and 
total  nitrogen,  and  in  case  of  naturally  poor  or  abnormal  soils  it  is 
well,  also,  to  have  determinations  made  of  the  total  potassium,  total 
magnesium,  and  total  calcium. 

The  chief  value  of  a  chemical  analysis  is  not  to  serve  as  a  guide 
in  the  application  of  some  certain  plant-food  element  in  readily 
available  form  for  the  special  benefit  of  the  next  crop,  but  rather  to 
serve  as  an  absolute  foundation  upon  which  methods  of  soil  treat- 
ment can  be  safely  based  for  the  adoption  of  systems  of  permanent 
soil  improvement. 

Thus,  if  the  plowed  soil  of  an  acre  is  found  to  contain  810  pounds 
of  total  phosphorus  and  47,600  pounds  of  total  potassium,  as  is  the 
case  with  the  yellow-gray  silt  loam  of  the  late  Wisconsin  glaciation, 
the  most  common  upland  soil  in  Lake  County,  Illinois,  then  a 
system  of  farming  which  will  increase  the  phosphorus  content  of 
the  soil  and  which  will  liberate  potassium  from  the  practically 
inexhaustible  supply  will  certainly  rest  upon  a  practical  and  truly 
scientific  foundation,  notwithstanding  the  fact  that  in  actual 
trials  the  application  of  soluble  potassium  salts  in  the  absence  of 
sufficient  decaying  organic  matter  might  produce  a  marked  effect 
on  crop  yields,  as  in  the  case  of  wheat  in  the  Rothamsted  experi- 
ments. 

In  practical  agriculture  the  first  soil  test  should  be  that  for  acid- 
ity, and  if  acidity  is  found  in  the  surface  and  more  marked  acidity 
in  the  subsoil,  the  first  treatment  should  be  the  application  of  2 
to  5  tons  per  acre  of  ground  limestone.  Following  this,  clover  or 
some  other  legume  should  be  grown,  inoculation  being  provided, 
if  necessary,  and  liberal  supplies  of  decaying  organic  matter  should 
then  be  provided  by  plowing  under  the  clover  either  directly  or 
in  the  form  of  manure.  Next,  some  form  of  phosphorus  should  be 
added  with  the  organic  matter,  more  especially  to  note  its  effect 
on  the  yield  of  succeeding  crops  of  legumes.  Finally,  if  necessary 
or  desirable,  some  soluble  salts  may  be  applied,  such  as  potassium 
chlorid,  sodium  chlorid  (common  salt),  kainit,  or  calcium  sulfate 
(gypsum  or  land  plaster),  to  note  whether  such  addition  would 
produce  at  least  temporary  profit  until  the  supply  of  decaying 


ANALYZING   AND    TESTING   SOILS  569 

organic  matter  becomes  adequate  to  liberate  sufficient  plant  food 
from  the  abundant  supplies  contained  in  the  soil.  Of  course,  if  the 
absolute  invoice  of  the  soil  shows  that  the  total  potassium  is  low,  as 
in  most  peaty  swamp  soils,  then  that  element  should  be  regularly 
provided  in  systems  of  permanent  agriculture;  and  likewise,  if 
the  total  magnesium  is  low,  it  is  certainly. advisable  to  apply  liberal 
amounts  of  magnesian  limestone.  Even  calcium  as  an  element  of 
plant  food  (especially  for  clover,  which  requires  29  pounds  of 
calcium  per  ton)  may  become  deficient,  as  is  plainly  the  case  with 
the  extensive  Leonardtown  loam  of  southern  Maryland. 

Plot  Experiments.   The  following  outline  is  one  of  the  simplest 
and  most  practical  series  of  plot  experiments: 

PLAN  FOR  PLOT  EXPERIMENTS  IN  SOIL  IMPROVEMENT 


PLDT  No. 

Son,  TREATMENT 

IOI 

IO2 

103 
104 

None,  except  crop  rotation 
Manure 
Manure  and  limestone 
Manure,  limestone,  and  phosphorus 

l°5 
1  06 
107 
108 

None,  except  crop  rotation 
Residues  turned  under 
Residues  and  limestone 
Residues,  limestone,  and  phosphorus 

109 
no 

Residues,  limestone,  phosphorus,  and  kainit 
None,  except  crop  rotation 

For  a  four- year  rotation,  such  as  wheat,  corn,  oats,  and  clover, 
there  should  be  four  different  series  similar  to  the  100  series,  in 
order  that  every  crop  may  be  represented  every  year.  The  use 
of  manure  should  be  in  amounts  such  as  could  easily  be  produced 
in  independent  systems  of  live-stock  farming  not  involving  the 
purchase  of  feed  in  excess  of  the  crops  sold.  The  use  of  crop  resi- 
dues should  include  all  products  except  the  grain  or  seed  to  be 
sold  in  grain  farming.  Thus,  the  clover  should  be  clipped  once  or 
twice  in  May  or  June  and  left  on  the  land,  the  cornstalks  should  be 
cut  and  plowed  under,  and  the  threshed  straw  (from  wheat,  oats, 
and  clover)  should  be  returned  to  the  land  either  immediately 
or  subsequently. 


570  VARIOUS   FERTILITY   FACTORS 

In  case  the  soil  contains  limestone,  that  application  could  be 
omitted,  and  perhaps  two  forms  of  phosphorus  tried,  such  as 
steamed  bone  meal  and  an  equal  value  of  raw  rock  phosphate. 
The  use  of  acid  phosphate  is  not  advised  for  such  experiments  be- 
cause of  its  indirect  effect,  due  in  part  to  its  marked  acidity,  and 
in  part  to  its  soluble  salt. content,  including  much  calcium  sulfate. 

As  a  rule,  the  applications  are  made  but  once  for  the  rotation, 
2  tons  of  limestone,  2000  pounds  of  raw  phosphate,  800  pounds  of 
steamed  bone  meal,  and  1000  pounds  of  kainit,  per  acre,  being 
recommended  for  a  four-year  rotation.  'For  each  ton  of  produce 
hauled  off  from  any  plot  during  the  rotation,  one  ton  of  manure 
can  be  returned,  even  though  the  wheat  and  some  part  of  the  other 
grain  should  be  sold,  and  by  exercising  great  care  and  making  large 
use  of  bedding,  it  is  possible  to  return  i  \  tons  of  average  fresh  ma- 
nure for  each  ton  of  produce  used  for  feed  and  bedding.  Of  course, 
the  crop  residues  in  the  grain  system  will  be  returned  in  accordance 
with  the  amounts  produced  on  the  respective  plots,  excepting  on 
plots  i,  5,  and  10,  from  which  all  crops  are  removed  and  nothing 
returned. 

Another  system  which  is  especially  designed  to  furnish  informa- 
tion concerning  the  needs  of  the  soil,  rather  than  to  demonstrate 
how  those  needs  should  be  supplied,  is  as  follows: 

PLAN  FOR  PLOT  EXPERIMENTS  WITH  FERTILIZERS 


PLOT  No. 

PLANT  FOOD  APPLIED 

I 
2 
3 

4 

None 
Dried  blood 
Steamed  bone  meal 
Potassium  sulfate 

5 
6 

7 
8 

None 
Blood  and  bone 
Blood  and  potassium  sulfate 
Bone  and  potassium  sulfate 

9 

10 

Blood,  bone,  and  potassium  sulfate 
None 

The  applications  should  be  at  the  rate  of  1000  pounds  of  dried 
blood,  200  pounds  of  steamed  bone  meal,  and  200  pounds  of  potas- 


ANALYZING  AND   TESTING   SOILS  571 

sium  sulfate,  for  each  year.  One  half  of  each  plot  may  be  treated 
with  limestone,  applied  at  the  rate  of  1000  pounds  per  acre,  and 
for  some  soils  magnesian  limestone  is  undoubtedly  preferable  to 
the  more  common  limestone,  which  contains  only  calcium  car- 
bonate. 

Some  rotation  of  crops  should  be  practiced,  such  as  corn,  oats, 
wheat,  and  timothy.  To  introduce  legumes  in  this  system,  largely 
destroys  the  value  of  the  test  with  nitrogen,  and  the  plan  is  designed 
to  discover  as  quickly  as  possible  what  the  soil  fails  to  furnish 
to  the  crop. 

When  definite  information  has  been  secured,  the  materials 
which  need  to  be  added  should  as  a  rule  be  applied  in  larger 
amounts  at  longer  intervals.  Thus  initial  applications  of  10  tons 
of  ground  limestone  and  even  3  or  4  tons  per  acre  of  fine  ground 
rock  phosphate  are  not  unreasonable  for  land  valued  at  $10  to 
$50  per  acre  which  the  owner  desires  to  improve  until  it  shall 
yield  as  much  as  is  produced  on  $150  or  $200  land. 


CHAPTER  XXXV 

RELATION    OF   FERTILITY   TO   APPEARANCE    OF    SOILS    OR 

CROPS 

IT  is  probably  not  too  much  to  say  that  the  average  man  is  ever 
on  the  alert  to  " discover"  the  cause  for  every  effect.  This  is  well, 
but  not  infrequently  two  or  three  examples  are  readily  accepted 
as  proof  sufficient  sometimes  to  become  a  tradition.  Thus  do  some 
people  still  plant  potatoes  in  the  dark  of  the  moon,  although,  as 
T.  B.  Terry  says,  it  were  better  to  plant  in  the  light  of  the  moon, 
when  one  can  see  to  work  late  at  night. 

To  find  a  "  Shakespere  "  plant  of  wheat  from  which  a  new  variety 
may  be  established  is  perhaps  a  laudable  search,  but,  as  a  rule, 
hauling  manure  is  a  more  remunerative  employment.  It  is  well 
that  some  men  have  the  "  gold  fever,"  but  those  of  large  experience 
and  observation  tell  us  that  more  money  is  buried  in  gold  mines 
than  is  ever  dug  out. 

Success  in  agriculture  depends  largely  upon  knowledge  and  work. 
Fortunate  is  the  man  who  knows  what  to  do  and  does  it.  Not  much 
knowledge  or  skill  is  required  to  secure  temporary  success  where 
rich,  virgin  land  is  accepted  as  a  gift  or  at  a  very  low  price,  and 
where  the  unearned  increment  amounts  to  $100  or  more  per  acre 
for  the  man  who  does  little  else  than  to  draw  upon  his  capital  stock 
for  support. 

Permanent  success  requires  knowledge,  thought,  investment, 
and  work,  and  success  for  the  many  lies  within  reach  along  these 
lines;  whereas,  sudden  riches  from  gold  mines,  oil  wells,  inventions, 
or  discoveries  are  rare  misfortunes;  and  there  is  no  more  free  land 
in  the  humid  section  of  the  United  States. 

Directions  are  often  given  by  which  it  is  held  that  one  can  tell 
from  the  appearance  of  the  crop  what  plant  food  is  lacking  in  the  soil. 
Thus  we  are  told  that  nitrogen  produces  a  rank  growth  of  straw  or 

572 


FERTILITY  AND   APPEARANCE 


573 


stalk,  and  retards  maturity,  and  that  small  growth  and  a  pale  color 
show  lack  of  nitrogen;  that  phosphorus  produces  the  seed  and  has- 
tens maturity,  and  that  poorly  filled  ears  and  heads  show  lack  of 
phosphorus;  that  weakness  of  straw  shows  lack  of  potassium. 
However,  these  and  other  " rules"  have  commonly  been  evolved 
from  experience  on  soils  of  one  class,  and  they  may  have  little  or 
no  value  on  other  soil  types. 

Any  kind  of  malnutrition  produces  imperfect  growth.  On  sand 
land  and  other  soils  deficient  in  nitrogen,  the  addition  of  nitrogen 
does  not  retard,  but  positively  hastens,  maturity,  sometimes  by  one 
or  two  weeks,  and  markedly  increases  the  development  of  the  seed 
or  grain.  On  peaty  swamp  lands,  which  are  well  supplied  with 
nitrogen,  the  plants  are  small  and  pale  or  yellowish  in  color,  and 
under  the  rule  appear  to  suffer  "nitrogen  hunger,"  but  rank 
growth,  dark  color,  and  well-filled  heads  or  ears  result  from  the 
addition  of  potassium.  On  soils  rich  in  nitrogen  and  potassium  and 
deficient  in  phosphorus,  the  growth  and  strength  of  straw  or  stalk, 
as  well  as  yield  of  grain,  are  markedly  increased  by  addition  of 
phosphorus;  and  100  bushels  of  good  sound  corn  will  often  mature 
where  the  soil  is  properly  balanced  two  weeks  in  advance  of  a  20- 
bushel  crop  grown  from  the  same  kind  of  seed  planted  at  the  same 
time  on  the  same  type  of  soil,  where  not  properly  balanced. 

Nitrogen  is  an  important  constituent  of  the  organic  matter  of 
the  soil;  consequently,  soils  rich  in  organic  matter  are  also  rich  in 
nitrogen;  and,  conversely,  soils  markedly  deficient  in  organic 
matter,  such,  especially,  as  worn  hill  lands  and  sand  soils,  are  also 
deficient  in  nitrogen.  Potassium  is  not  a  fixed  constituent  of  or- 
ganic matter,  is  easily  leached  from  plant  residues,  and  is  usually 
deficient  in  peat  soils,  as  well  as  in  soils  derived  largely  from  quartz, 
as  from  some  residual  sandstones.  Carbonates  and  phosphates 
derived  from  shells  and  skeletons  may  have  some  relation,1  and 

1  Whitson  has  suggested  (Wisconsin  Agricultural  Experiment  Station  Bulletins 
1 39 and  174)  a  vice  versa  relationship;  namely,  that  there  is  correlation  between  soil 
acidity  and  lack  of  phosphorus.  He  says:  "So  far  no  case  has  been  found  in 
which  acid  soils  have  not  shown  a  need  of  phosphate."  While  it  is  true  that  many 
acid  soils  are  deficient  in  phosphorus,  there  is  no  necessary  correlation  between 
these  two  facts.  The  highly  phosphatic  soils  of  Tennessee  and  Kentucky  are  some- 
times acid,  and  some  of  the  peat  soils  of  Illinois,  which  are  as  rich  in  phosphorus  as 
any  soil  in  the  state,  are  distinctly  acid.  This  is  the  case,  for  example,  with  the  deep 


574  VARIOUS   FERTILITY   FACTORS 

limestone  soils  are  often  well  supplied  with  phosphorus,  phosphatic 
limestones  being  especially  rich  in  phosphate.  Phosphorus  is  also 
a  fixed  constituent  in  most  organic  matter,  and  soils  rich  in  humus 
usually  have  at  least  a  fair  supply  of  phosphorus.  Silicate  minerals 
contain  much  potassium,  and  clay  soils  or  silt  soils  derived  from 
silicates  usually  contain  sufficient  undecomposed  minerals  to  in- 
sure a  high  content  of  potassium.  These  facts  serve  to  indicate  to 
some  extent  correlation  between  the  physical  appearance  of  the 
soil  and  its  chemical  composition;  but  these  indications  have  no 
such  value  as  the  chemical  invoice  of  the  total  plant  food  contained 
in  the  soil. 

peat  on  the  Manito  experiment  field,  but  both  the  soil  analysis  and  the  field  experi- 
ments show  that  the  soil  is  not  deficient  in  phosphorus.  (See  Tables  15,  16,  17,  and 


CHAPTER  XXXVI 

FACTORS  IN  CROP  PRODUCTION 

THERE  are  six  essential  positive  factors  in  the  production  of 
agricultural  crops,  which  may  be  designated  by  the  single  words: 

i.    Seed.  2.   Home.  3.   Heat. 

4.   Light.  5.    Moisture.        6.   Food. 

There  are  many  negative  factors  against  which  the  plant  should 
be  protected,  such  as  injury  from  insects,  birds,  or  other  animals, 
fungous  or  other  diseases  or  parasites,  weeds,  and  even  against  an 
excess  of  some  positive  factors,  such  as  moisture.  To  ignore  any 
important  essential  factor  is  certainly  to  be  one-sided  or  short- 
sighted. 

Seed.  The  seed  is  a  factor  of  much  importance.  The  Illinois 
Station  has  produced,  as  an  average  yield  of  three  years,  15.6 
bushels  per  acre  of  one  variety  of  wheat  and  6.  i  bushels  of  another 
variety,  in  careful  comparable  tests  on  the  same  type  of  soil.  The 
fact  that  the  soil  was  poor  helps  to  show  the  character  of  the  wheat, 
because  it  requires  a  good  variety  to  make  a  fair  yield  on  poor  soil. 
Aside  from  varietal  differences,  the  vitality  or  vigor  of  the  special 
lot  of  seed  is  important,  and  the  selection  of  the  best  seed  from  a 
given  lot  is  certainly  good  practice.  Large  seed  are,  as  a  rule,  better 
than  small  seed,  even  though  they  may  be  of  the  same  variety  and 
all  of  good  vitality.  Thus,  as  an  average  of  7  years,  the  Ontario 
Agricultural  College  produced  62  bushels  of  oats  per  acre  from  large 
seed  and  only  47  bushels  from  small  seed,  both  selected  from  the 
same  stock  each  year.  The  selection  and  breeding  of  plants  is  at 
least  as  successful  as  the  breeding  of  animals.  Thus  may  plants 
be  developed  for  power  to  yield  or  for  special  purposes.  The  Illi- 
nois Station  has  in  ten  years'  breeding  developed  two  strains  of 
corn  one  of  which  now  contains  6  per  cent  more  protein  than  the 
other,  and  two  other  strains  one  of  which  contains  about  three 
times  as  much  oil  as  the  other,  all  four  strains  having  been  bred 

575 


576  VARIOUS    FERTILITY   FACTORS 

from  a  single  variety  of  corn.  Likewise,  the  sugar  beet  has  been 
developed  by  breeding  under  the  most  exact  scientific  control  until 
its  sugar  content  has  been  changed  from  4  per  cent  to  more  than 
12  per  cent,  and  until  about  one  half  of  the  world's  supply  of  sugar 
is  now  made  from  beets.  But  shall  we  practically  ignore  other 
equally  essential  factors  because  of  the  importance  of  seed? 

Home  of  the  plant.  The  home  of  the  plant  may  vary  from  a  stiff, 
compact,  almost  impervious  clay,  offering  a  very  shallow  feeding 
range  for  plant  roots,  to  a  porous,  friable,  easily  penetrated,  fine 
sandy  loam,  affording  a  very  deep  feeding  range.  To  markedly 
modify  the  physical  character  of  the  soil  is,  as  a  rule,  a  difficult  and 
expensive  problem.  Thorough  underdrainage  and  large  use  of 
organic  matter,  including  deep-rooting  plants,  which  are  the  best 
subsoilers,  and  sometimes  heavy  applications  of  marl  or  ground 
limestone  (10  tons  or  more  per  acre)  will  do  much  to  improve  the 
clay  soils,  and  heavy  applications  of  "  clay  "  (say  one  wagon  load 
to  the  square  rod)  will  greatly  improve  some  very  light  sand  soils. 
An  old  English  saying  runs: 

"  Clay  on  sand  is  money  in  the  hand ; 
Sand  on  clay  is  money  thrown  away." 

Temperature.  A  proper  temperature  is  important  in  crop  pro- 
duction, although  some  plants  grow  well  in  cool  weather,  while 
others  do  best  under  tropical  conditions.  Dark  soils  are  warmer 
than  light-colored  soils,  a  difference  of  several  degrees  being  noted 
during  the  forenoon  in  the  early  summer,  and  this  difference  extends 
to  a  depth  of  several  inches;  but  the  largest  control  of  soil  tempera- 
ture lies  in  the  control  of  soil  moisture.  Improperly  drained  soils 
are  cold  soils,  because  enormous  quantities  of  heat  are  required 
to  remove  surplus  water  from  the  soil  by  the  process  of  evapora- 
tion. Thus,  to  melt  ice  requires  only  79  heat  units,  and  to  raise 
water  from  the  freezing  point  to  the  boiling  point  requires  only 
100  heat  units,  but  to  evaporate  water  requires  536.4  heat  units. 
If  the  surplus  soil  water  can  be  removed  by  underdrainage,  the 
sun's  energy  may  then  be  expended  in  warming  the  soil. 

Light.  Light  is  an  absolute  essential  in  the  most  fundamental 
process  of  plant  growth,  photosynthesis.  One  of  the  most  damag- 


FACTORS   IN    CROP   PRODUCTION  577 

ing  effects  of  weeds  is  that  they  shut  off  the  light  to  a  greater  or 
less  extent  from  the  agricultural  plant.  Nurse  crops  drilled  north 
and  south  permit  the  strong  midday  light  to  reach  the  young  clover, 
and  thus  insure  a  hardier  clover  plant  than  when  the  nurse  crop  is 
sown  broadcast  or  drilled  in  an  east  and  west  direction.  In  green- 
house cultures  light  is  very  commonly  the  limiting  factor  in  plant 
growth.  However,  under  ordinary  field  conditions,  the  light  is 
probably  adequate  for  crop  yields  at  least  ten  times  the  present 
averages. 

Moisture.  Moisture  is  perhaps  the  most  variable  factor  in 
crop production;  and,  in  consequence,  many  seem  to  think  that 
if  we  have  timely  rains,  we  should  always  have  good  crops;  although 
on  almost  every  farm,  there  are  some  patches  of  ground  which 
produce  twice  as  much  as  others,  even  though  the  rainfall,  seed, 
preparation,  cultivation,  etc.,  are  alike  on  both  areas. 

It  may  safely  be  stated  that  when  corn  or  other  crops  begin  to 
"  fire  "  in  time  of  partial  drouth  the  real  cause  of  the  "  firing  "  is 
more  commonly  due  to  a  lack  of  plant  food  than  to  a  lack  of  mois- 
ture for  its  own  sake.  To  be  sure,  a  more  ideal  rainfall,  which  we 
cannot  control,  would  help  to  render  available  a  more  nearly  ade- 
quate supply  of  plant  food,  even  from  a  poor  soil;  but,  on  the  other 
hand,  a  liberal  enrichment  of  the  soil,  which  we  can  control,  will 
often  render  unnecessary  additional  rainfall.  Almost  every  season 
in  some  part  of  Illinois,  we  observe  the  "  firing  "  of  corn  on  unfer- 
tilized land  where  the  soil  is  incapable  of  producing  more  than  25 
to  50  bushels  per  acre,  while  at  the  same  time  on  adjoining  properly 
fertilized  plots  which  yield  75  to  100  bushels,  and  where  the  crops 
are  actually  drawing  much  more  moisture  from  the  soil,  there  is 
little  or  no  evidence  of  "  firing."  Even  in  the  pot-culture  lab- 
oratory, where  water  is  daily  supplied  in  sufficient  abundance, 
plants  "  fire  "  with  inadequate  food  supplies.  In  other  words,  the 
lower  leaves  die,  and  much  of  the  plant  food  which  they  contain  is 
translocated  to  the  new,  growing  parts,  in  order  that  reproduction 
may  ensue  if  possible. 

The  conservation  of  moisture  in  humid  sections  is  a  matter  whose 
importance  is  commonly  greatly  exaggerated.  If  the  expense  so 
much  advised  for  extra  cultivation  were  devoted  to  a  more  liberal 
use  of  manure,  clover,  limestone,  and  phosphorus,  greater  and 


578 


VARIOUS    FERTILITY   FACTORS 


more  lasting  profits  would  result.  As  an  average  of  six  years' 
experiments  at  the  Illinois  Station,  Professor  George  E.  Morrow 
produced  70.3  bushels  of  corn  per  acre  with  ordinary  cultivation 
(four  times,  or  twice  each  way) ,  while  eight  extra  cultivations  in- 
creased the  yield  to  only  72.8  bushels.  Furthermore,  where  no 
cultivation  whatever  was  practiced,  the  land  having  been  well  pre- 
pared and,  subsequent  to  planting,  kept  clean  by  clipping  the  weeds 
off  at  the  surface  of  the  ground,  the  average  yield  for  the  same  six 
years  was  68.3  bushels  per  acre.  About  one  half  of  all  the  increase 
from  the  extra  cultivation  during  the  six  years  was  produced  dur- 
ing one  especially  dry  season.  For  the  other  five  years  the  extra 
cultivation  was  wasted  energy;  and  as  an  average  the  increase 
produced  was  far  below  the  cost  of  the  extra  work. 

Table  119  shows  the  results  of  more  recent  experiments  at  the 
Illinois  Station,  which  include  the  effect  of  plowing,  preparation 
of  seed  bed,  cultivation,  irrigation,  and  fertilization. 

TABLE  119.   EFFECT  OF  SOIL  PREPARATION,  CULTIVATION,  IRRIGATION,  AND 

FERTILIZATION:  ILLINOIS  EXPERIMENTS 

Corn,  Bushels  per  Acre 


PLOT 

No. 

SOIL  TREATMENT 

1906 

1907 

1908 

I 

Land  not  plowed  ;  not  cultivated  ;  weeds  clipped 
off  at  surface  

3§J 

32-3 

2 

Land  plowed  and  well  prepared,  but  not  culti- 
vated; weeds  clipped  off  at  surface  

44.0 

39-6 

3 

Land  plowed  and  well  prepared,  but  nothing  done 
after  planting  ;  weeds  allowed  to  grow  .... 

None 

None 

4-4 

4 

Land  plowed,  well  prepared,  well  cultivated     .     . 

44-7 

49.6 

29.4 

5 

Land  plowed,  well  prepared,  well  cultivated,  and 
irrigated  in  dry  weather    

46.2 

49.8 

33-8 

6 

Land  plowed,  well  prepared,  well  cultivated,  irri- 
gated, and  heavily  fertilized      

60.7 

IO2.2 

S2.8 

In  1908  a  rainfall  of  10.28  inches  in  30  days  during  the  usual 
time  for  corn  planting  necessitated  very  late  preparation  of  the 
land,  and  with  very  light  rainfall  during  the  remainder  of  the 
season  (only  8.93  inches  between  May  23  and  November  22)  the 


FACTORS   IN    CROP   PRODUCTION 


579 


weeds  on  the  uncultivated  plot  failed  to  smother  the  crop  so  com- 
pletely as  to  entirely  prevent  the  formation  of  ears,  which  in  nor- 
mal seasons  is  the  common  result  of  the  unrestricted  growth  of 
weeds. 

It  is  a  matter  of  surprise  to  many  people  that  a  good  crop  of  corn 
can  be  produced  with  no  cultivation  after  the  crop  is  planted;  but 
they  forget  that  40  bushels  of  wheat,  80  of  oats,  3  tons  of  clover, 
etc.,  are  produced  on  good  soil  with  no  cultivation  after  planting. 
On  good  land  in  humid  sections  the  greatest  benefit  of  cultivation 
is  due  to  the  killing  of  weeds.  For  soils  deficient  in  plant  food, 
especially  in  nitrogen,  frequent  cultivation  will  hasten  the  decay 
of  organic  matter,  encourage  nitrification,  and  often  markedly 
increase  the  crop  yield.  Thus,  on  the  worn  hill  lands  at  Ithaca, 
New  York,  the  Cornell  Station  has  shown  very  beneficial  results 
from  long-continued  cultivation  of  potatoes;  but  the  question 
still  remains  if  more  clover  plowed  under  would  not  have  given 
better  yields  at  less  expense  and  have  left  the  land  in  better  con- 
dition for  subsequent  crops. 

In  the  semiarid  region,  fallow  cultivation  is  practiced  during  one 
season,  the  soil  being  stirred  after  every  rain,  in  order  to  prevent 
evaporation  and  thus  store  up  sufficient  moisture  in  the  soil  to 
give  the  crop  a  good  start,  especially  a  fall-sown  crop  like  winter 
wheat,  which  with  moderate  rainfall  the  next  spring  will  usually 
produce  a  good  yield.  On  the  other  hand,  the  much-talked-of 
"  dry  farming "  is  a  great  misnomer.  Above  everything  else, 
every  success  in  "  dry  farming  "  is  coincident  with  a  fair  amount 
of  rainfall  in  a  semiarid  region;  and  the  prospective  investor  is 
warned  not  to  be  misled  by  the  numerous  exaggerated  reports 
of  successful  "dry  farming";  and  the  author  speaks,  not  only 
from  scientific  data,  but  also  from  fourteen  years'  practical  ex- 
perience in  a  semiarid  state.  He  has  seen  20  to  30  bushels  of 
wheat  and  corresponding  yields  of  other  crops  produced  for  several 
years  with  a  moderate  rainfall  well  distributed,  and  he  has  also 
seen  this  period  followed  by  four  years  in  succession  with  so  little 
rainfall  that  no  sort  of  dry  farming  could  produce  a  profitable  crop. 

Certainly  it  is  possible  and  practicable  to  conserve  and  accumu- 
late moisture  with  very  moderate  rainfall,  so  that  one  crop  can  be 
grown  every  two  years,  and  much  can  be  done  to  advantage  where 


58o 


VARIOUS    FERTILITY   FACTORS 


crops  are  grown  every  year;  but  the  fact  remains  that  at  least  75 
per  cent  of  the  talk  of  "  dry  farming  "  is  falacious.  It  is  to  be  cred- 
ited largely  to  land  agents,  farmers  of  short  experience,  and  to 
one-sided  enthusiasts.  When  it  is  found  impossible  to  win  con- 
fidence in  the  "  dry  farming  "  theory,  the  advocate  insists  that 
the  seasons  in  the  semiarid  region  have  changed,  that  more  abun- 
dant rainfall  follows  the  plow,  and  that  the  semiarid  region  has 
become  humid. 

It  is  true,  as  stated  above,  that  a  series  of  wet  years  may  follow 
a  dry  series,  but  it  is  not  true  that  seasons  change  measurably  in 
any  permanent  way  during  human  experience. 

The  accompanying  chart  showing  the  total  annual  rainfall  at 
North  Platte,  Nebraska,  for  the  34  years,  1875  to  1908,  presents 
some  interesting,  instructive,  and  valuable  data. 


sggg 


20 

18.86 
18 
17 
16 
15 
II 
13 
12 
11 
10 


30 

29 

28 

27 

26 

26 

21 

23 

22 

21 

20 

18.86 

18 

17 

18 

15 

11 

13 

12 

11 

10 

0 

8 

7 


PRECIPITATION  (.inches)  AT  NORTH  PLATTE,  NEBRASKA,  FOR  THIRTY-FOUR 
YEARS  — 1875  TO  1908 

It  will  be  observed  that  the  average  rainfall  for  the  seven  years, 
1902  to  1908,  is  23.17  inches,  and  it  will  also  be  noted  that  every 
year  has  been  above  normal,  with  the  exception  of  1903,  which  was 
slightly  below.  Previous  to  1902  was  a  remarkable  period  of  nine 
years  when  every  year  was  distinctly  below  normal,  the  rainfall 


FACTORS   IN   CROP   PRODUCTION  581 

ranging  from  11.21  to  17.09.  It  is  not  surprising,  perhaps,  that 
"  dry  farming  "  should  succeed  fairly  well  in  recent  years  with  a 
rainfall  ranging  from  1 8  to  28  inches,  and  there  is  reason  enough 
to  convince  many1  that  rainfall  follows  the  plow.  However,  the 
heaviest  rainfall  on  record  is  for  1883  (29.88  inches),  and  the  aver- 
age for  the  ten  years,  1877  to  1886,  is  only  .38  of  an  inch  below  the 
average  for  the  last  ten  years,  while  the  average  for  the  first  17 
years  is  .64  of  an  inch  greater  than  the  average  for  the  last 
17  years,  according  to  the  records  of  the  34  years. 

A  matter  worthy  of  important  consideration  is  the  distribution 
of  rainfall.  A  rainfall  of  15  to  20  inches  is  sufficient  for  very  fair 
crops  if  it  comes  at  the  rate  of  3  inches  a  month  from  April  to 
September;  but,  if  two  or  three  torrential  showers  of  4  or  5  inches 
each  all  within  a  month  or  six  weeks  are  parts  of  the  total,  the  rain- 
fall may  be  very  inadequate. 

The  author  is  firmly  of  the  opinion  that  most  of  the  cultivable 
semiarid  lands  in  the  United  States  where  the  average  annual 
rainfall  exceeds  15  inches  should  be  and  will  be  occupied,  and  also 
that  a  very  satisfactory  measure  of  prosperity  can  be  attained  by 
those  who  farm  those  lands  under  the  best  methods;  but  it  should 
not  be  forgotten  that  there  are  certain  to  be  periods  of  severe  drouth 
sometimes  for  several  years  in  succession;  and,  unless  adequate 
provision  is  made  against  such  times,  there  will  be  suffering  for 

1  An  experience  reported  to  the  author  by  Mr.  N.  S.  Spencer,  a  resident  of 
Champaign  County,  Illinois,  cannot  fail  to  be  of  interest,  and  may  be  of  some  value, 
to  students  of  semiarid  agriculture.  Mr.  Spencer  stated  that  he  went  into  central 
Nebraska  some  years  ago  and  saw  growing  in  the  fields  wheat  crops  that  yielded 
35  bushels  per  acre  on  very  low-priced  land,  and  he  had  positive  assurance  that  ex- 
cellent crops  had  been  grown  the  year  before  and  also  in  previous  years.  He  bought 
a  large  farm,  and  broke  up  400  acres  the  same  season,  on  which  wheat  was 
seeded  in  the  fall.  The  following  year  crop  failure  was  common,  and  he  threshed 
no  wheat.  However,  there  were  some  good  summer  rains  and  he  prepared  the 
land  well  and  again  seeded  400  acres  of  wheat,  but  again  the  rain  failed  and 
he  threshed  no  wheat.  Once  more  the  summer  rains  were  sufficient  to  enable 
him  to  put  the  land  in  good  condition,  and  he  sowed  300  acres  of  wheat,  which, 
however,  also  resulted  in  complete  failure.  He  then  gave  up  the  land  upon  which 
he  had  made  two  payments,  disposed  of  his  stock  and  tools  as  well  as  he  could, 
and  found  that  his  total  loss  for  the  three  years'  experience  amounted  to  about 
$10,000. 

Soon  after  hearing  this  story,  the  author  looked  up  the  rainfall  record  as  reported 
above  for  North  Platte,  and  then  stated  to  Mr.  Spencer  that  he  must  have  bought 
his  land  in  1892,  which  was  found  to  be  correct. 


582 


VARIOUS   FERTILITY   FACTORS 


animals  and   possibly  for  the  people,  unless  relieved   by  food 
supplies  from  other  sections. 


AVERAGE  ANNUAL  PRECIPITATION  IN  DIFFERENT  PARTS  OF  THE  UNITED 
STATES  (in  inches) 


The  accompanying  map  of  the  United  States  showing  the  average 
annual  rainfall  is  based  upon  the  record  of  the  United  States 
Weather  Bureau,  and  furnishes  some  exceedingly  valuable  infor- 
mation. It  will  be  noted  that  the  average  rainfall  is  about  35 
inches  for  eastern  Kansas  and  southeast  Nebraska,  about  25 
inches  for  central  Kansas  and  east-central  Nebraska,  and  about  15 
inches  for  the  western  parts  of  those  states.  The  average  annual 
rainfall  of  the  United  States  varies  from  less  than  10  inches  in 
the  Great  Basin  to  more  than  60  inches  over  small  areas  on  the 
coast. 

Some  portion  of  the  arid  region  will  be  reclaimed  by  irrigation; 
but  while  this  subject  is  receiving  much  attention,  with  extensive 
advertising  of  both  private  and  public  enterprises,  it  can  never  be 
a  very  large  factor  in  American  agriculture.  Director  Frederick 
H.  Newell,  of  the  United  States  Reclamation  Service,  makes  the 
following  statements  concerning  the  arid  region  ("  Conservation  of 


FACTORS   IN   CROP   PRODUCTION  583 

Natural  Resources "   published  by  the  American  Academy  of 
Political  and  Social  Science,  Philadelphia,  1909) : 

"If  all  the  run-off  waters  of  this  region  could  be  conserved  and  employed  in 
irrigation,  the  total  area  reclaimed  might,  perhaps,  be  brought  to  nearly 
60,000,000  acres.  .  .  .  Large  portions  of  the  water  of  the  arid  region  cannot 
be  used  in  irrigation,  as  no  irrigable  land  exists  upon  which  it  can  be  brought  at 
feasible  cost." 

"With  present  data,  the  closest  statement  is  probably  under  60,000,000  acres 
and  between  40,000,000  and  50,000,000  acres,  including  the  lands  now  under 
ditch."  (About  13,000,000  acres  are  now  under  irrigation.) 

For  comparison  it  may  be  noted  that  the  state  of  South  Dakota 
contains  48,000,000  acres,  and  the  estimated  total  area  of  arid  land 
that  can  still  be  brought  under  irrigation  in  the  United  States  is 
equal  to  only  one  state  like  Illinois.  Director  Newell  estimates 
that  the  total  land  areas  that  may  possibly  be  brought  under  irri- 
gation might  support,  directly  and  indirectly,  10  million  people, 
or  about  10  per  cent  of  our  present  population. 

It  should  be  kept  in  mind  that  the  fertility  even  of  irrigated  lands 
must  be  maintained  if  they  are  to  continue  productive.  With 
large  use  of  turbid  water  there  is  always  soil  enrichment,  but 
reservoir  water  adds  little  or  no  fertility  to  the  soil,  as  witness  the 
low  yields  of  irrigated  lands  in  India.  In  his  Handbook  of  Indian 
Agriculture,  Mukerji  makes  the  following  statements: 

"The  best  crops  of  wheat  are  grown  on  lands  newly  brought  under  canal 
irrigation.  Where  canal  water  is  used  for  irrigation  for  a  number  of  years,  the 
outturn  is  found  to  fall  off  even  below  the  original  level.  .  .  .  No  manure  is 
required  for  dearh  land  which  is  annually  renovated  with  silt." 

In  this  connection  it  is  of  interest  to  know  that  the  estimated 
area  of  reclaimable  swamp  land  in  the  United  States  is  less  than 
80  million  acres,  which  would  provide  about  two  million  4o-acre 
farms,  thus  furnishing  homes  for  another  10  million  people  corre- 
sponding to  the  normal  increase  in  our  population  for  five  or  six 
years. 


CHAPTER  XXXVII 

ESSENTIAL    FACTORS    OF    SUCCESS   IN   FARMING 

THERE  are  three  factors  which  govern  success  in  such  an 
enterprise  as  farming:  (i)  knowledge,  (2)  executive  ability,  and 
(3)  business  ability. 

First,  we  must  have  the  necessary  knowledge  to  make  definite 
plans  under  which  permanent  success  will  be  possible.  Merely 
because  one  has  considered  that  he  was  making  money  while  he 
has  been  wearing  out  a  rich  soil,  which  may  have  cost  him  but 
little  to  begin  with,  is  no  assurance  that  he  will  be  able  to  succeed 
when  he  has  to  deal  with  high-priced,  partially  exhausted  land. 

Second,  one  may  have  sufficient  knowledge  to  plan  well,  but, 
if  he  lacks  the  executive  ability  to  properly  carry  out  his 
plans,  he  will  surely  fail.  It  is  at  this  point  that  landowners 
frequently  misjudge  the  young  graduate  from  the  agricultural 
college.  They  fail  to  distinguish  between  the  knowledge  of  im- 
portant fundamental  facts,  which  the  young  man  possesses,  and 
the  necessary  executive  ability  to  handle  men  and  to  get  work 
done,  which,  as  a  rule,  the  young  man  does  not  possess. 

Third,  one  must  have  judgment  and  ability  in  financial  matters, 
for  purchases  must  be  made  with  economy  and  the  farm  products 
must  be  disposed  of  to  advantage,  if  profit  is  to  result.  Business 
dealing  is  an  essential  part  of  the  farm  enterprise;  and  it  matters 
not  how  well  the  farm  system  is  planned  or  how  well  the  plans  are 
executed  in  the  production  of  crops,  the  poor  business  man,  who 
pays  too  much  for  the  things  he  buys,  buys  things  which  he  need 
not  buy,  or  fails  to  buy  the  things  he  needs,  who  sells  his  produce 
in  poor  condition,  holds  produce  when  he  ought  to  sell  it,  or  sells 
when  he  ought  to  hold  it,  will  certainly  not  attain  a  high  degree 
of  success  in  farming. 

The  manufacturer  employs  an  expert  for  a  definite  purpose  and 
the  expert  renders  the  required  service  to  the  great  advantage  of 
his  employer;  but  what  manufacturer  would  think  of  turning  over 

584 


ESSENTIAL   FACTORS    OF   SUCCESS   IN   FARMING     585 

the  complete  management  of  a  complex  business  to  an  inexperienced 
young  man,  even  though  he  were  able  to  analyze £he  raw  materials 
and  point  out  some  absolute  essentials  for  the  highest  grade  of 
finished  products? 

Let  the  landowner  of  executive  and  business  ability  take  the 
graduate  from  the  agricultural  college  as  a  junior  partner,  until 
he  has  had  the  opportunity  to  acquire  those  essentials  in  the  school 
of  experience  under  the  wiser  guidance  of  the  older  man,  who 
should  not  forget,  however,  that  land  which  has  been  running  down 
for  half  a  century  cannot  be  built  up  in  a  year  so  as  to  pay  both 
cost  and  profit  on  the  improvement. 

An  investment  of  $2  per  acre  per  annum  which  always  pro- 
duces an  increase  above  the  preceding  year  of  2  bushels  of  corn  per 
acre  (and  equivalent  amounts  of  other  crops  in  the  rotation)  fur- 
nishes corn  as  follows: 

COST  or  CORN  PER  BUSHEL 

First  year $1.00 

Second  year 50 

Third  year 33^ 

Fourth  yeaf 25 

Fifth  year       '. 20 

Sixth  year 163 

Eighth  year 12! 

Tenth  year 10 

These  figures  mean  that  land  which  increases  in  productiveness  at 
the  rate  of  2  bushels  per  annum  would  rise  from  50  bushels  to  70 
bushels  per  acre  in  ten  years'  time,  and  if  this  change  can  be  brought 
about  at  a  cost  of  $2  per  acre  per  annum,  it  will  be  an  extremely 
profitable  investment,  although  there  may  be  an  apparent  loss  for 
the  first  few  years.  And  this  does  not  take  into  account  the  certain 
fact  that  if  the  land  is  not  properly  treated,  it  will  sooner  or  later  de- 
crease in  productive  power  below  the  5o-bushel  yield. 

Even  large  annual  expense  will  ultimately  prove  profitable  if 
it  provides  for  a  system  of  farming  under  which  the  land  steadily 
increases  in  productiveness;  whereas,  if  a  system  is  followed 
which  allows  the  soil  to  become  depleted  of  any  essential  constituent, 
failure  must  finally  result,  whether  we  grow  one  grain  crop  year 
after  year,  rotate  the  grain  crops,  or  use  inadequate  amounts  of 
manure,  clover,  or  commercial  fertilizers. 


CHAPTER  XXXVIII 

THE    VALUE    OF   LAND 

TABLE  120  is  presented  in  order  to  emphasize  to  some  degree 
the  very  great  importance  of  producing  and  maintaining  large 
crop  yields.  It  will  be  understood,  of  course,  that  these  data,  at 
most,  represent  only  approximately  average  conditions.  Thus 
the  prices  for  produce  (75  cents  for  wheat,  40  cents  for  corn,  30 
cents  for  oats,  and  $6  a  bushel  for  clover  seed)  represent  approxi- 
mately the  lo-year  average  prices  for  those  products  in  the  states 
where  such  a  crop  rotation  is  most  practicable. 

It  is  not  suggested  that  the  student  accept  these  data,  but  only 
that  he  accept  or  consider  the  principle  of  measuring  land  values 
by  crop  returns. 

In  the  expense  for  soil  treatment,  allowance  is  made  for  the  pur- 
chase of  2  tons  of  limestone  per  acre  (charged  to  the  clover  crop) ; 
for  at  least  as  much  phosphorus  as  will  be  contained  in  the  grain 
and  seed  produced;  for  an  extra  seeding  of  clover  on  the  wheat 
ground,  to  be  plowed  under  the  next  spring  for  corn;  for  the 
return  of  all  straw  and  stalks  to  the  land  including  extra  work  of 
hauling,  and  spreading  straw,  cutting  and  disking  stalks,  etc.;  and 
even  for  returning  the  potassium  sold  in  the  grain.  The  regular 
clover  crop  is  mowed  once  or  twice  and  left  lying  on  the  land, 
only  the  seed  crop  being  harvested. 

The  expense  for  growing  the  crops  includes  only  the  preparation 
of  the  seed  bed,  the  seed,  and  seeding,  and,  in  the  case  of  corn,  the 
cultivation.  Under  "  harvest  and  market  "  is  included  the  cost  of 
binding  twine,  thresh  bills,  etc.  For  taxes  is  allowed  the  uniform 
rate  of  £  per  cent  of  the  actual  valuation  of  the  land,  which  is 
fixed  by  its  interest-earning  capacity,  5  per  cent  interest  being 
used  as  the  standard  rate. 

The  minimal  grain  yields  assumed  for  Table  120  are  above  the 
minimal  averages  for  the  United  States,  and  the  maximal  yields  in 

586 


THE   VALUE    OF   LAND 


587 


TABLE  120.   VALUE  OF  LAND  MEASURED  BY  CROP  YIELDS 


CROP  YIELDS 
PER  ACRE 

GROSS 
VALUE  OF 
CROP 

ANNUAL  EXPENSE,  PER  ACRE 

NET 
VALUE  OF 
CROP 

NET 
VALUE  OF 
LAND  PER 
ACRE 

Son 
Treat- 
ment 

To 

grow 
Crops 

Harvest 
and 
Market 

Taxes  on 
Land 

Total 
Annual 
Expense 

AN  ACRE  OF  WHEAT  AT  75  CENTS  A  BUSHEL 


10  bushels 

$  7-5o 

$1.00 

$3-00 

$1.00 

$0.23 

$  5-23 

$  2.27 

S  45-45 

20  bushels 

15.00 

2.OO 

3.00 

2.00 

•73 

7-73 

7-27 

145-45 

30  bushels 

22.50 

3-00 

3-00 

3.00 

1.23 

10.23 

12.27 

245-45 

40  bushels 

30.00 

4.0O 

3.00 

4.00 

i-73 

12.73 

17.27 

345-45 

50  bushels 

37-So 

5-00 

3.00 

5.00 

2.23 

15-23 

22.27 

445-45 

AN  ACRE  OF  CORN  AT  40  CENTS  A  BUSHEL 

20  bushels 

$  8.00 

$1.80 

$4.00 

$1.00 

$0.11 

$  6.91 

$  1.09 

$  21.81 

40  bushels 

16.00 

3.60 

4.0O 

2.OO 

.58 

10.18 

5.82 

116.36 

60  bushels 

24.00 

5-40 

4-OO 

3.00 

1.05 

13-45 

10.55 

210.91 

80  bushels 

32.00 

7.20 

4.0O 

4-00 

i-53 

16.73 

15-27 

305-45 

100  bushels 

40.00 

9.00 

4.0O 

5.00 

2.OO 

20.00 

20.00 

400.00 

AN  ACRE  OF  OATS  AT  30  CENTS  A  BUSHEL 

20  bushels 

$  6.00 

$0.50 

$3-00 

$I.OO 

$0.14 

$  4.64 

$  1.36 

$  27.27 

40  bushels 

I2.OO 

I.OO 

3-00 

2.OO 

•55 

6-55 

5-45 

109.09 

60  bushels 

18.00 

1.50 

3-00 

3-00 

•95 

8-45 

9-55 

190.91 

80  bushels 

24.00 

2.OO 

3-00 

4.OO 

1.36 

10.36 

13.64 

272.72 

100  bushels 

30.00 

2.50 

3.00 

5-00 

1.77 

12.27 

17-73 

354-54 

AN  ACRE  OF  CLOVER  AT  $6  A  BUSHEL  FOR  SEED 

i  bushel 

$  6.00 

$3-00 

$I.OO 

$1.50 

$0.05 

$5-55 

S  0.45 

$    9.09 

2  bushels 

12.  OO 

3.00 

I.OO 

3-00 

•45 

7-45 

4-55 

90.91 

3  bushels 

iS.OO 

3-00 

I.OO 

4-5° 

.86 

9-36 

8.64 

172.72 

4  bushels 

24.00 

3.00 

I.OO 

6.00 

1.27 

11.27 

12.73 

254-54 

5  bushels 

30.00 

3-00 

I.OO 

7-5° 

1.68 

13.18 

16.82 

336-36 

AVERAGE  FOR  THE  4-  YEAR  ROTATION 

$  6.88 

S  5-59 

$  1.29 

$  25.80 

J3-75 

7-98 

5-77 

115.40 

20.63 

10.38 

10.25 

205.00 

27.50 

12.77 

14-73 

294.60 

34.38 

i5-i7 

19.21 

384.20 

588  VARIOUS   FERTILITY   FACTORS 

the  table  are  less  than  have  been  produced  on  good  soil  in  good 
seasons.  They  are  not  likely  to  be  secured  as  an  average  even  on 
the  best  treated  land,  but  they  are  not  too  high  to  serve  as  an  ideal 
toward  which  we  may  well  strive  and  which  we  may  expect  to  reach 
under  favorable  conditions. 

If  in  the  general  equalization,  or  balance,  between  live-stock 
farming  and  grain  the  value  of  clover  seed  markedly  decreases, 
beans,  peas,  and  other  edible  legumes  will  to  some  extent  be  sub- 
stituted for  clover  in  the  rotation  of  crops. 

Perhaps  the  most  valuable  fact  brought  out  in  Table  120  is  the 
very  rapid  increase  that  occurs  in  net-earning  power,  and  conse- 
quently in  land  value,  after  fixed  expenses  are  covered.  Thus, 
land  which  produces  a  2o-bushel  crop  of  corn  is  valued  at  $21.81 
an  acre;  while,  if  the  crop  yield  is  doubled,  the  land  value  is 
multiplied  more  than  five  times. 

With  60  bushels  of  corn  and  yields  of  equivalent  rank  for  other 
crops,  the  land  becomes  worth  more  than  $200  an  acre,  and  with 
50  bushels  of  wheat,  100  of  corn  and  oats,  and  5  bushels  of  clover 
seed,  the  average  value  of  the  land  approaches  $400  an  acre. 

A  careful  consideration  of  the  figures  given  in  Table  1 20  will  show 
that  the  expenses  allowed  for  the  large  yields  are  relatively  much 
more  ample  than  those  allowed  for  the  small  yields.  Thus,  5  cents 
a  bushel  is  allowed  for  husking  and  marketing  corn;  and,  while 
this  is  ample  for  corn  yielding  80  bushels  per  acre,  it  is  probably 
inadequate  for  a  2o-bushel  crop.  Likewise,  the  taxes  on  poor  land 
are,  as  a  very  general  rule,  relatively  higher  than  on  good  land.  This 
is  due  to  the  fact  that  most  of  the  taxes  are  for  local  purposes 
(schools,  roads,  bridges,  etc.),  and  the  actual  expense  in  a  poor 
land  section  is  about  the  same  as  where  the  lands  are  rich.  Thus, 
land  which  produces  only  20  bushels  of  corn  may  pay  30  cents  an 
acre  tax,  while  land  producing  80  bushels  (in  another  section  of  the 
state)  may  not  be  taxed  more  than  50  cents  an  acre.  To  be  sure, 
the  state  tax  might  be  properly  equalized,  but  the  county  and  local 
taxes  are  often  more  than  ten  times  the  state  tax.1 

It  will  easily  be  noted  that  when  crop  yields  sink  slightly  below 

1  Likewise  the  federal  tax,  though  indirect,  is  usually  about  ten  times  the  state 
tax. 


THE   VALUE    OF   LAND  589 

the  minimal  figures  given  in  Table  120,  the  land  becomes  practically 
valueless  for  business  or  investment  purposes. 

Agriculture  is  often  referred  to  as  the  most  independent  occupa- 
tion; and  in  the  struggle  against  poverty,  in  countries  with  in- 
creasing population  and  failing  resources,  it  is  certainly  true  that, 
after  men  in  most  other  lines  of  occupation  have  literally  starved 
out,  the  farmer  will  continue  to  eke  out  an  existence.  In  fact,  he 
may  still  have  bread  and  potatoes,  milk  and  butter,  eggs  and 
poultry,  and  even  vegetables,  fruits,  sirup,  and  honey,  for  the 
support  of  his  own  family,  long  after  he  has  practically  ceased  to 
buy  or  sell  in  support  of  a  dependent  urban  population.  Thus, 
the  city  is  the  first  to  feel  the  country's  poverty;  and  for  their  own 
preservation  the  men  of  the  town  or.  city  must  contribute  their 
influence  toward  the  development  of  systems  of  permanent  agri- 
culture. 

Bankers,  merchants,  grain  dealers,  physicians,  editors,  teachers, 
and  ministers,  as  well  as  educated  landowners,  because  they  have 
trained  minds  and  are  able  with  moderate  study  to  acquire  a  cor- 
rect and  adequate  understanding  of  the  fundamental  principles 
of  soil  improvement,  must  exert  their  influence  over  those  who 
are  less  able  to  secure  such  positive  knowledge  but  who  may  own 
or  control  much  of  the  land,  lest  the  lands  generally  become  so 
impoverished  that  they  will  support  only  the  agricultural  people, 
who,  of  course,  have  the  first  right  to  the  food  they  produce. 

Under  such  conditions,  land  may  have  no  value  as  a  source  of 
profit,  and  still  be  invaluable  as  a  means  of  existence.  Because  a 
given  amount  of  grain  will  support  about  five  times  as  many 
people  as  will  the  meat  or  milk  that  can  be  made  from  it,  grain-fed 
animals  are  not  maintained  in  the  poorest  countries;  and,  when 
human  labor  becomes  worth  little  more  than  the  cost  of  exist- 
ence, it  is  substituted  for  the  labor  of  beasts  of  burden;  and 
whatever  domestic  animals  are  kept  must  be  supported  upon 
uncultivated  lands  or  upon  refuse  products  not  usable  as  human 
food  or  more  valuable  for  direct  use  as  fertilizer. 


CHAPTER  XXXIX 

TWO   PERIODS    IN   AGRICULTURAL   HISTORY 

THE  following  quotations,  separated  by  a  lapse  of  twenty  cen- 
turies, cannot  fail  to  interest  the  student  of  American  agriculture : 

"The  land  must  rest  every  second  year,  or  be  sown  with  lighter  kinds  of 
seeds,  which  prove  less  exhausting  to  the  soil."  —  VARRO  (B.C.  116  to  28). 

"A  field  is  not  sown  entirely  for  the  crop  which  is  to  be  obtained  the  same 
year,  but  partly  for  the  effect  to  be  produced  in  the  following;  because  there 
are  many  plants  which,  when  cut  down  and  left  on  the  land,  improve  the  soil. 
Thus  lupines,  for  instance,  are  plowed  into  a  poor  soil  in  lieu  of  manure." 

—  VARRO. 

"Horse  dung  is  about  the  best  suited  for  meadow  land,  and  so  in  general  is 
that  of  beasts  of  burden  fed  on  barley ;  for  manure  produced  from  this  cereal 
makes  the  grass  grow  luxuriantly."  —  VARRO. 

"Plowing  the  land  simply  means  rendering  the  earth  porous  and  friable, 
which  must  tend  to  increase  its  productiveness."  —  CATO  (B.C.  95  to  46). 

"Wherein  does  a  good  system  of  agriculture  consist?  In  the  first  place,  in 
thorough  plowing;  in  the  second  place,  in  thorough  plowing;  and,  in  the 
third  place,  in  manuring."  —  CATO. 

"Take  care  to  have  your  wheat  weeded  twice  —  with  the  hoe,  and  also  by 
hand."  —  CATO. 

"A  soil  to  be  fertile  must,  above  all  things,  be  light  and  friable,  and  this  con- 
dition we  seek  to  bring  about  by  the  operation  of  plowing." 

—  VIRGIL  (B.C.  70  to  19). 

"Linseed,  poppy,  and  oats  exhaust  the  soil."  —  VIRGIL. 

"Still  will  the  seeds,  tho  chosen  with  toilsome  pains 
Degenerate,  if  man's  industrious  hand 
Cull  not  each  year  the  largest  and  the  best. 
'Tis  thus  by  destiny,  all  things  decay 
And  retrograde,  with  motion  unperceived."  . 

—  VIRGIL'S  Georgics. 

"On  the  other  side  of  the  Po,  the  use  of  ash  is  viewed  so  favorably  by  farmers, 
that  they  actually  prefer  it  to  the  manure  furnished  by  their  cattle." 

—  PLINY  (A.D.  23  to  79). 

"On  large  estates  fields  are  alternately  allowed  to  lie  fallow  in  order  to  save 
manure."  —  PLINY. 


TWO   PERIODS   IN   AGRICULTURAL   HISTORY     591 

"No  one  gifted  with  common  sense  will  ever  permit  himself  to  be  persuaded 
that  our  earth  has  grown  old,  as  man  grows  old.  The  sterility  of  our  fields  is  to 
be  imputed  to  our  doings,  because  we  hand  over  the  cultivation  of  them  to  the 
unreasoning  management  of  ignorant  and  unskillful  slaves." 

—  COLUMELLA  (first  century,  A.D.). 

"Some  of  the  leguminous  plants  manure  the  soil, according  toSaserna, and 
make  it  fruitful,  whilst  other  crops  exhaust  it,  and  make  it  barren.  Lupines,  beans, 
peas,  lentils,  and  vetches  are  reported  to  manure  the  land.  Where  no  kind  of 
manure  is  to  be  had,  I  think  the  cultivation  of  lupines  will  be  found  the  readiest 
and  best  substitute.  If  they  are  sown  about  the  middle  of  September  in  a  poor 
soil,  and  then  plowed  in  (when  well  grown),  they  will  answer  as  well  as  the 
best  manure."  —  COLUMELLA. 

"The  best  forage  plants  are  lucerne  (alfalfa),  fenugreek,  and  vetches.  Lu- 
cerne may  be  placed  in  the  foremost  rank  of  such  plants;  for  when  once  sown  it 
lasts  ten  years,  fattens  lean  cattle,  and  has  a  salutary  action  on  sick  cattle.  It 
must  be  carefully  weeded  at  first,  lest  the  weeds  choke  the  tender  lucerne." 

—  COLUMELLA. 

It  was  in  1859  that  Baron  von  Liebig  wrote  as  follows,  regard- 
ing these  and  similar  ancient  teachings: 

"All  these  rules  had,  as  history  tells  us,  only  a  temporary  effect;  they  has- 
tened the  decay  of  Roman  agriculture ;  and  the  farmer  ultimately  found  that  he 
had  exhausted  all  his  expedients  to  keep  his  fields  fruitful  and  reap  remunera- 
tive crops  from  them.  Even  in  Columella's  time,  the  produte  of  the  land  was 
only  fourfold." 

"It  is  not  the  land  itself  that  constitutes  the  farmer's  wealth,  but  it  is  in  the 
constituents  of  the  soil,  which  serve  for  the  nutrition  of  plants,  that  this  wealth 
truly  consists." 

"The  deplorable  effects  of  the  spoliation  system  of  farming  are  nowhere 
more  strikingly  evident  than  in  America,  where  the  early  colonists  in  Canada,  in 
the  state  of  New  York,  in  Pennsylvania,  Virginia,  Maryland,  etc.,  found  tracts 
of  land,  which  for  many  years,  by  simply  plowing  and  sowing,  yielded  a  succes- 
sion of  abundant  wheat  and  tobacco  harvests." 

"We  all  know  what  has  become  of  those  fields.  In  less  than  two  generations, 
though  originally  teeming  with  fertility,  they  were  turned  into  deserts,  and  in 
many  districts  brought  to  a  state  of  such  absolute  exhaustion,  that  even  now, 
after  having  been  fallow  for  more  than  a  hundred  years,  they  will  not  yield  a 
remunerative  crop  of  a  cereal  plant." 

"The  American  farmer  despoils  his  farm  without  the  least  attempt  at 
method  in  the  process.  When  it  ceases  to  yield  him  sufficiently  abundant  crops, 
he  simply  quits  it,  and  with  his  seed  and  plants,  betakes  himself  to  a  fresh  farm; 


592  VARIOUS   FERTILITY   FACTORS 

for  there  is  plenty  of  good  land  to  be  had  in  America;   and  it  would  not  be 
worth  his  while  to  work  the  same  farm  to  absolute  exhaustion." 

"Agriculture  is,  of  all  industrial  pursuits,  the  richest  in  facts,  and  the  poorest 
in  their  comprehension.  Facts  are  like  grains  of  sand  which  are  moved  by  the 
wind,  but  principles  are  these  same  grains  cemented  into  rocks." 

"Science  is  conservative  in  her  nature,  not  destructive.  She  does  not  reject 
the  truths  discovered  by  practice,  but  receives  them;  they  are  never  disputed 
by  her,  but  are  examined  and  receive  from  her  their  proper  import  and  further 
application." 

"Modern  agriculture  has,  up  to  this  time,  no  connection  with  the  history  of 
the  development  of  man.  That  history  is  the  mirror  which  reflects  not  only 
his  errors  and  failures,  but  also  his  onward  progress.  But  modern  agriculture 
rejects  the  idea  of  ever  being  in  error,  and  therefore  she  knows  nothing  of  prog- 
ress." 

It  was  also  in  1859  that  Abraham  Lincoln  spoke  as  follows: 

"To  speak  entirely  within  bounds,  it  is  known  that  50  bushels  of  wheat, 
or  zoo  bushels  of  Indian  corn,  can  be  produced  from  an  acre.  .  .  .  Take  50  of 
wheat,  and  100  of  corn,  to  be  the  possibility,  and  compare  it  with  the  actual 
crops  of  the  country.  Many  years  ago  I  saw  it  stated,  in  a  patent -office  report, 
that  18  bushels  was  the  average  crop  of  wheat  throughout  the  United  States. 
...  As  to  Indian  corn,  and,  indeed,  most  other  crops,  the  case  has  not  been 
much  better." 

"What  would  b£  the  effect  upon  the  farming  interest  to  push  the  soil  up  to 
something  near  its  full  capacity?  Unquestionably  it  will  take  more  labor  to 
produce  fifty  bushels  from  an  acre  than  it  will  to  produce  ten  bushels  from  the 
same  acre;  but  will  it  take  more  labor  to  produce  fifty  bushels  from  one  acre 
than  from  five?  Unquestionably,  more  thorough  cultivation  will  require  more 
labor  to  the  acre;  but  will  it  require  more  to  the  bushel?  If  it  should  require 
just  as  much  to  the  bushel,  there  are  some  probable,  and  several  certain,  ad- 
vantages in  favor  of  the  thorough  practice.  It  is  probable  it  would  develop 
those  unknown  causes  which  of  late  years  have  cut  down  our  crops  below  their 
former  average.  It  is  almost  certain,  I  think,  that,  by  deeper  plowing,  analysis 
of  the  soils,  experiments  with  manures  and  varieties  of  seeds,  observance  of 
reasons,  and  the  like,  these  causes  would  be  discovered  and  remedied.  It  is 
certain  that  thorough  cultivation  would  spare  half,  or  more  than  half,  the 
quantity  of  land.  This  proposition  is  self-evident,  and  can  be  made  no  plainer 
by  repetitions  or  illustrations.  The  cost  of  land  is  a  great  item,  even  in  new 
countries,  and  it  constantly  grows  greater  and  greater,  in  comparison  with  other 
items,  as  the  country  grows  older." 

"No  other  human  occupation  opens  so  wide  a  field  for  the  profitable  and 
agreeable  combination  of  labor  with  cultivated  thought,  as  agriculture.  I 
know  nothing  so  pleasant  to  the  mind  as  the  discovery  of  anything  that  is  at 


TWO   PERIODS   IN   AGRICULTURAL   HISTORY     593 

once  new  and  valuable  —  nothing  that  so  lightens  and  sweetens  toil  as  the  hope- 
ful pursuit  of  such  discovery.  And  how  vast  and  how  varied  a  field  is  agri- 
culture for  such  discovery!  The  mind,  already  trained  to  thought  in  the 
country  school,  or  higher  school,  cannot  fail  to  find  there  an  exhaustless  source 
of  enjoyment.  Every  blade  of  grass  is  a  study;  and  to  produce  two  where 
there  was  but  one  is  both  a  profit  and  a  pleasure.  And  not  grass  alone,  but 
soils,  seeds,  and  seasons  —  hedges,  ditches,  and  fences  —  draining,  droughts, 
and  irrigation  —  plowing,  hoeing,  and  harrowing  —  reaping,  mowing,  and 
threshing  —  saving  crops,  pests  of  crops,  diseases  of  crops,  and  what  will  pre- 
vent or  cure  them  —  implements,  utensils,  and  machines;  their  relative  merits, 
and  how  to  improve  them  —  hogs,  horses,  and  cattle  —  sheep,  goats,  and 
poultry  —  trees,  shrubs,  fruits,  plants,  and  flowers  —  the  thousand  things  of 
which  these  are  specimens  —  each  a  world  of  study  within  itself. 

"In  all  this,  book  learning  is  available.  A  capacity  and  taste  for  reading 
gives  access  to  whatever  has  already  been  discovered  by  others.  It  is  the  key, 
or  one  of  the  keys,  to  the  already  solved  problems.  And  not  only  so :  it  gives 
a  relish  and  facility  for  successfully  pursuing  the  unsolved  ones.  The  rudi- 
ments of  science  are  available,  and  highly  available.  Some  knowledge  of 
botany  assists  in  dealing  with  the  vegetable  world  —  with  all  growing  crops. 
Chemistry  assists  in  the  analysis  of  soils,  selection  and  application  of  manures, 
and  in  numerous  other  ways.  The  mechanical  branches  of  natural  philosophy 
are  ready  help  in  almost  everything,  but  especially  in  reference  to  implements 
and  machinery. 

"The  thought  recurs  that  education  —  cultivated  thought  —  can  best  be 
combined  with  agricultural  labor,  or  any  labor,  on  the  principle  of  thorough 
work;  that  careless,  half-performed,  slovenly  work  makes  no  place  for  such 
combination ;  and  thorough  work,  again,  renders  sufficient  the  smallest  quantity 
of  ground  to  each  man;  and  this,  again,  conforms  to  what  must  occur  in  a 
world  less  inclined  to  wars  and  more  devoted  to  the  arts  of  peace  than  hereto- 
fore. Population  must  increase  rapidly,  more  rapidly  than  in  former  times, 
and  erelong  the  most  valuable  of  all  arts  will  be  the  art  of  deriving  a  comfortable 
subsistence  from  the  smallest  area  of  soil.  No  community  whose  every  member 
posesses  this  art,  can  ever  be  the  victim  of  oppression  in  any  of  its  forms.  Such 
community  will  be  alike  independent  of  crowned  kings,  money  kings,  and  land 
kings. 

"It  is  said  an  Eastern  monarch  once  charged  his  wise  men  to  invent  him  a 
sentence  to  be  ever  in  view,  and  which  should  be  true  and  appropriate  in  all 
times  and  situations.  They  presented  him  the  words,  'And  this,  too,  shall 
pass  away.'  How  much  it  expresses!  How  chastening  in  the  hour  of  pride! 
How  consoling  in  the  depths  of  affliction !  'And  this,  too,  shall  pass  away.' 
And  yet,  let  us  hope,  it  is  not  quite  true.  Let  us  hope,  rather,  that  by  the 
best  cultivation  of  the  physical  world  beneath  and  around  us,  and  the  intellec- 
tual and  moral  world  within  us,  we  shall  secure  an  individual,  social,  and 
political  prosperity  and  happiness,  whose  course  shall  be  onward  and  upward, 
and  which,  while  the  earth  endures,  shall  not  pass  away." 


594  VARIOUS   FERTILITY  FACTORS 

"  Public  prosperity  is  like  a  tree  :  agriculture  is  its  roots ;  industry  and  com- 
merce are  its  branches  and  leaves.  If  the  root  suffers,  the  leaves  fall,  the 
branches  break,  and  the  tree  dies."  —  CHINESE  PHILOSOPHY. 

"  Let  us  never  forget  that  the  cultivation  of  the  earth  is  the  most  important 
labor  of  man.  Unstable  is  the  future  of  a  country  which  has  lost  its  taste  for 
agriculture.  If  there  is  one  lesson  of  history  that  is  unmistakable,  it  is  that 
national  strength  lies  very  near  the  soil."  —  DANIEL  WEBSTER. 

"  The  farm  is  the  basis  of  all  industry,  but  for  many  years  this  country  has 
made  the  mistake  of  unduly  assisting  manufacture,  commerce,  and  other  ac- 
tivities that  center  in  cities,  at  the  expense  of  the  farm."  — JAMES  J.  HILL. 

NOTE.  In  the  Orange  Judd  Farmer  (January  22,  1910),  Professor  F.  H. 
King,  who  has  recently  visited  the  Orient,  reports  estimates  based  upon 
Japanese  statistics  as  follows  (Japan's  population  is  nearly  53  millions): 

Japan  cultivates  less  than  14  million  acres  of  land,  to  which  are  applied 
annually  about  24  million  tons  of  human  manure ;  23  million  tons  of  compost 
made  from  animal  manures  and  waste  materials  mixed  with  much  grass,  straw, 
sods,  and  mud  (from  canals  and  ditches);  5  million  tons  of  green  weeds, 
gathered  from  "weed  lands  "  on  uncultivated  hills ;  and  776,000  tons  of  ashes. 
These  materials  make  an  average  annual  application  of  3.8  tons  per  acre,  con- 
taining, according  to  the  accepted  analyses  of  official  Japanese  chemists,  54 
pounds  of  nitrogen,  14.8  pounds  of  phosphorus,  and  29.2  pounds  of  potassium. 
In  1908  Japan  imported  753,074  tons  of  commercial  fertilizers  (phosphates, 
etc.),  which  would  probably  raise  to  20  pounds  per  acre  per  annum  the  amount 
of  phosphorus  applied.  Besides  this,  large  use  is  made  of  legume  crops  as 
green  manures,  and,  where  rice  is  grown,  grass,  straw,  and  chaff  are  used 
extensively  for  direct  application  to  the  land  as  organic  manures. 

From  the  data  given  here  and  in  Table  121,  it  will  be  seen  that  the  total  excre- 
ments per  individual  per  year  amount  to  about  900  pounds,  and  contain  about 
6  pounds  of  nitrogen,  I  pound  of  phosphorus,  and  i|  pounds  of  potassium. 

In  comparison  it  may  be  stated  that  data  gathered  from  digestion  experi- 
ments with  24  men  during  a  period  of  220  days,  by  Dr.  H.  S.  Grindley,  Uni- 
versity of  Illinois,  showed  the  average  total  excrements  per  year  as  1032  pounds, 
containing  9.6  pounds  of  nitrogen  and  i  .03  pounds  of  phosphorus ;  while  Wolff 
reports  a  total  of  1035  pounds,  containing  10.5  pounds  of  nitrogen,  i  .3  of  phos- 
phorus, 1 .8  of  potassium,  and  6.9  pounds  of  salt  (NaCl). 

When  we  consider  that  nitrogen  can  be  secured  by  legumes  from  the  inex- 
haustible atmospheric  supply,  that  potassium  is  exceedingly  abundant  in  most 
soils,  measured  by  the  amount  necessarily  sold  in  either  grain  farming  or  live- 
stock farming,  and  that  the  United  States  is  exporting  each  year,  for  about  2 
cents  a  pound,  twice  as  much  phosphorus  as  leaves  our  farms  in  the  total  wheat 
crop  of  the  country,  then  the  "  argument "  in  favor  of  discarding  our  present 
system  of  city  sewage  disposal  for  that  of  China  does  not  appear  to  be  financially 
sound,  with  the  present  cost  of  labor  in  the  United  States. 


APPENDIX 
SECTION   I 

THE  PRODUCTION  OF  PHOSPHATE  ROCK1 

THE  occurrence  of  rock  phosphate  in  the  United  States  has  a  very 
important  bearing  upon  the  agricultural  industry,  since  certain  classes 
of -plant  life  cannot  exist  without  the  presence  of  phosphoric  acid  in  the 
soil.  Growing  crops  deplete  the  soil  of  its  phosphoric  acid,  and  if  no 
steps  are  taken  to  restore  this  substance,  the  soil  must  eventually  be- 
come nonproductive. 

Florida,  South  Carolina,  and  Tennessee  have  for  several  years  been 
the  main  sources  of  phosphate  in  the  United  States.  North  Carolina, 
Alabama,  and  Pennsylvania  have  produced  phosphate  rock,  but  never  on 
a  large  scale,  and  there  is  at  present  no  production  from  these  states.  In 
1900  Arkansas  entered  the  field  as  a  producer,  and  in  1906  a  new  field 
was  discovered  in  Wyoming,  Idaho,  and  Utah. 

Phosphate  mining  began  in  the  United  States  in  1868,  in  South  Caro- 
lina. The  existence  of  the  rock  had  been  known  since  1837,  but  the 
possibilities  of  its  commercial  use  were  not  recognized  until  1859. 

Until  1888  South  Carolina  enjoyed  a  monopoly  of  the  phosphate 
industry  of  the  United  States.  In  that  year  Florida  came  forward  as  a 
phosphate  state,  with  a  production  of  3000  long  tons.  In  1904  the  pro- 
duction surpassed  that  of  South  Carolina,  and  Florida  has  maintained 
its  lead  up  to  the  present  time. 

In  1892  phosphate  was  discovered  in  Tennessee,  and  two  years  later 
the  production  from  that  state  was  19,188  long  tons.  In  1899  Tennes- 
see went  ahead  of  South  Carolina,  the  production  from  the  latter  state 
having  decreased  steadily  since  1893. 

The  production  of  phosphate  from  South  Carolina  from  the  beginning 
of  the  industry  in  1867  to  the  year  1888,  during  which  period  that  state 
was  the  only  producer,  was  4,442,945  long  tons,  valued  at  $23,697,019. 

1  Extracts  from  "  Advance  Chapter  from  Mineral  Resources  of  the  United  States, 
Calendar  Year  1908,"  by  F.  B.  Van  Horn  of  the  United  States  Geological  Survey. 

595 


596 


APPENDIX 


The  following  table  shows  the  total  production  in  the  United  States  from 
1867  to  1908: 

MARKETED  PRODUCTION  OF  PHOSPHATE  ROCK  IN  THE  UNITED  STATES, 
1867-1908,  AND  EXPORTATION  FOR  1899-1908 


YEAR 

QUANTITY 
(Long  Tons) 

VALUE 

YEAR 

QUANTITY 
(Long  Tons) 

VALUE 

EXPORTED 
(Long  Tons) 

1867-1887 

4,442945 

$23,697019 

1899  .      . 

1,515702 

$5,084076 

867790 

1888   .      . 

448567 

2,018552 

1900  .      . 

1,491216 

5,359248 

619995 

1889   .      . 

550245 

2,937776 

1901  . 

1,483723 

5,3l6403 

729539 

1890   .      . 

510499 

3,213795 

1902  .      . 

1,490314 

4,693444 

802086 

1891    .      . 

587988 

3,65I][50 

1903  .      . 

I,58l576 

5,3J9294 

785259 

1892    .      . 

681571 

3,296227 

1904  .      . 

1,874428 

6,580875 

842484 

1893    .      . 

941368 

4,136070 

1905  .      . 

1,947190 

6,763403 

934940 

1894   .      . 

996949 

3,479547 

1906  .      . 

2,080957 

8,579437 

904214 

I89S    .      . 

1,038551 

3,606094 

1907  .      . 

2,265343 

10,653558 

I,Ol82I2 

1896    .      . 

930779 

2,803372 

1908  .      . 

2,386138 

",399124 

1,188411 

1897   .      . 

1,039345 

2,673202 

1898   .      . 

1,308885 

3,453460 

Of  the  total  quantity  (31,594,279  tons)  South  Carolina  has  furnished 
12,138,454  tons;  Florida,  14,087,833  tons;  Tennessee,  5,315,422  tons; 
and  other  states,  53, 570  tons.  In  twenty-one  years  Florida  has  produced 
more  phosphate  than  has  South  Carolina  in  thirty-two  years. 

The  phosphate  deposits  range  in  age  from  the  Ordovician  in  Tennessee 
to  the  Tertiary  in  Florida,  occurring  also  in  the  Devonian  in  Tennessee 
and  Arkansas,  and  in  the  Carboniferous  in  the  Wyoming-Idaho-Utah 
field. 

Within  the  last  few  years  a  large  area  of  phosphate-bearing  rock  has 
been  discovered  in  the  western  United  States.  This  discovery  is  of 
much  importance,  since  it  opens  a  new  field  in  an  area  which  is  tributary 
to  the  great  agricultural  region  of  the  Middle  West.  The  phosphate 
occurs  over  a  considerable  area  in  southeastern  Idaho,  southwestern 
Wyoming,  and  northeastern  Utah.  It  is  found  in  rocks  of  "Upper 
Carboniferous"  age  in  a  series  of  shales  and  limestones,  100  feet  thick, 
within  which  are  several  beds  of  phosphate  rock  ranging  in  thickness 
from  a  few  inches  to  10  feet.  At  the  base  of  the  series  is  a  limestone, 
and  6  to  8  inches  of  soft  brown  shale  separates  this  from  the  principal 
phosphate  bed,  which  is  5  to  6  feet  thick.  This  phosphate  bed  is  oolitic 
in  character  and  high  in  phosphoric  acid.  There  are  in  the  series  several 
other  beds  ranging  from  a  few  inches  to  10  feet  in  thickness,  and  sepa- 


APPENDIX 


597 


rated  by  thin  beds  of  limestone  or  shale.  Usually  one  and  sometimes 
two  of  these  beds  at  a  given  section  are  workable,  and  probably  some  of 
the  others  will  eventually  be  mined.  The  lime  phosphate  content  in 
the  workable  beds  varies  from  65  to  80  per  cent,  with  an  average  of  72 
per  cent. 

DEVELOPMENT  AND  PRODUCTION 

The  newness  of  the  field,  the  lack  of  transportation  facilities,  and  the 
high  freight  rates  have  prevented  the  development  of  this  phosphate 
territory  to  any  great  extent,  although  there  has  been  some  shipment 
from  Montpelier,  Idaho,  in  the  last  three  years. 

The  world's  production  of  phosphate  rock,  1905  to  1907,  inclusive, 
is  given  in  the  following  table : 

WORLD'S  PRODUCTION  OF  PHOSPHATE  ROCK,  1905-1907,  BY  •  COUNTRIES,  IN 

METRIC  TONS 


COUNTRY 

1905 

1906 

1907 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

QUANTITY 

VALUE 

Algeria      .     .     . 
Aruba  .... 
Belgium    .     .     . 
Canada     .     .     . 
Christmas  Island 
France      .     .     . 
Norway     .     .     . 
Spain    .... 
Tunis  .... 
United  Kingdom 
United  States     . 

334784 
23307 
193305 
1338 

99519 
476720 
2522 

J37o 
52I731 

$1,225126 
42188 
332292 
8876 

(a) 

2,093118 
33768 

7295 
1,812493 

333531 
26138 
152140 
52i 
92010 
469408 
3482 
1300 
796000 

$  965600 
(a) 
282612 
4024 

(«) 
1,872000 

46524 
7592 
2,304400 

373763 
(b) 
(b) 
748 
(b) 
43I237 
(b) 

$  2,142352 

6018 

1,876736 

1,069000 

43 
2,301588 

(a) 

224 

10,653558 

i»97834S 

6,763403 

2,114252 

8,579437 

(a)  Value  not  reported.  (b)  Statistics  not  yet  available. 

AVAILABLE  PHOSPHATE  DEPOSITS 

The  known  phosphate  deposits  of  the  United  States  are  distributed 
principally  among  four  localities:  (i)  along  the  west  coast  of  Florida, 
running  back  20  to  25  miles  inland;  (2)  along  the  coast  of  South  Caro- 
lina, extending  6  to  20  miles  inland;  (3)  in  central  Tennessee;  and 
(4)  in  an  area  comprising  southeastern  Idaho,  southwestern  Wyoming, 
and  northeastern  Utah.  In  addition  to  these  areas,  some  deposits  occur 
in  north-central  Arkansas,  along  the  Georgia-Florida  state  line,  and  in 


598  APPENDIX 

North  Carolina,  Alabama,  Mississippi,  and  Nevada,  but  these  are 
merely  of  low  grade  and  not  utilized  at  the  present  time.  The  three 
important  deposits  first  mentioned  have  been  worked  from  ten  to  thirty 
years ;  the  fourth  is  a  new  field  which  has  as  yet  had  but  a  small  output. 

ESTIMATED  LIFE   OF  UNITED   STATES   PHOSPHATE   DEPOSITS 

The  rate  of  increase  in  production  for  the  last  twenty  years  has  been 
117  per  cent  for  each  decade.  Assuming  that  this  rate  of  increase  will 
continue,  it  will  require  but  a  comparatively  short  time  to  exhaust  the 
available  supply  of  phosphate  rock  in  the  United  States.  The  annual 
production,  at  the  stated  rate  of  increase,  will  be  approximately 
17,000,000  tons  in  1932. 

It  is  hardly  probable  that  the  rate  of  increase  in  production  will  be  so 
great  as  for  the  last  decade,  since  the  agricultural  lands  of  the  Middle 
West  do  not  at  present  need  artificial  assistance.  But  increasing  popu- 
lation, with  its  accompanying  intensive  farming,  will  eventually  force 
these  states  to  the  use  of  fertilizing  materials.  The  reclamation  of  arid 
lands  in  the  West  will  probably  postpone  the  day,  but  even  those  lands 
will  early  need  some  assistance  to  grow  the  large  crops  which  will  be 
required  of  them. 

Of  course,  the  vast  amount  of  low-grade  rock  which  is  not  now  avail- 
able will  be  in  reserve,  and  some  time  before  the  exhaustion  of  the  high- 
grade  phosphates  we  shall  doubtless  have  begun  to  use  this  rock.  The 
increasing  price  of  the  60  to  80  per  cent  phosphate  will  have  a  hastening 
effect  on  the  utilization  of  the  present  low-grade  material.  The  deposits 
of  Arkansas,  Georgia,  North  Carolina,  Alabama,  Tennessee,  and  the 
West,  which  run  from  30  to  50  per  cent  in  lime  phosphate,  will  be  avail- 
able to  draw  upon  after  the  high-grade  rock  is  exhausted.  This  class  of 
deposits,  especially  in  Tennessee  and  the  Western  States,  will  afford  an 
enormous  tonnage,  but,  based  upon  present  available  deposits,  the  life 
of  the  phosphates  must  at  best  be  a  short  one. 

FOREIGN  DEPOSITS 

Deposits  of  phosphate  rock  exist  in  Algeria,  France,  New  Zealand, 
Canada,  Russia,  Spain,  Tunis,  Belgium,  French  Guiana,  and  some  of 
the  South  Sea  Islands.  The  deposits  of  France  and  Belgium  are  practi- 
cally exhausted,  only  those  of  low  grade  remaining.  Concerning  the 
other  countries  no  information  as  to  reserve  tonnage  is  at  hand  except  for 
the  three  South  Sea  Islands  —  Ocean,  Pleasant,  and  Makatea.  These 


APPENDIX 


599 


three  islands  have  deposits  which  are  estimated  to  aggregate  60,000,000 
tons  of  high-grade  phosphate  rock. 

It  would  appear  certain  that  the  phosphate  deposits  of  the  United 
States  are  to  be  drained  for  the  benefit  of  the  worn-out  farm  lands  of 
foreign  countries.  So  far  as  the  deposits  of  Florida,  Tennessee,  and 
South  Carolina  are  concerned,  this  cannot  be  easily  prevented,  but  it 
has  been  suggested  that  "the  production  of  the  newly  opened  Western 
fields  may  be  preserved  for  the  United  States  by  retaining,  in  the  govern- 
ment, title  to  all  the  phosphate  rock  in  the  lands  now  belonging  to  the 
United  States,  and  by  leasing  these  deposits  under  appropriate  terms. 
In  the  lease  could  be  included  a  clause  providing  that  the  lessee  shall 
agree  to  mine  phosphate  rock  only  for  domestic  consumption." 


SECTION  II 

MODEL  FERTILIZER  LAW 

The  following  is  offered  as  a  model  law  for  governing  the  sale  of  com- 
mercial fertilizers,  conforming  to  a  report  adopted  by  the  Association  of 
American  Agricultural  Colleges  and  Experiment  Stations.  (See  Pro- 
ceedings 1  Twelfth  Annual  Convention  (1906),  page  128,  Bulletin  184,  of 
the  Office  of  Experiment  Stations,  United  States  Department  of  Agri- 
culture ;  also  Proceedings  2  24th  Annual  Convention  of  the  Association 

1  "  Providing  concurrent  action  is  taken  by  the  Association  of  Official  Agricul- 
tural Chemists  and  the  American  Chemical  Society,  your  committee  favors  the 
adoption  of  the  element  system  for  reporting  analytical  results  in  the  analysis  of 
soils,  ashes,  and  fertilizers,  and  recommends  that  the  association  urge  those  respon- 
sible for  fertilizer  legislation  to  have  the  laws  changed,  if  necessary,  and  as  soon 
as  practicable,  to  meet  with  these  recommendations,  if  concurred  in." 

"The  committee  also  recommends  that  in  case  of  the  adoption  of  the  foregoing 
there  be  required  to  be  printed  on  the  bag  or  on  the  tag  to  be  attached  to  the  bag 
or  to  accompany  fertilizers  sold  in  bulk  an  explanatory  statement  naming  the 
materials  in  which  the  plant  food  is  carried." 

3  "  That  the  association  vote  upon  the  advisability  of  permitting  the  use  of  a 
dual  system  of  nomenclature,  where  desirable,  with  a  view  to  the  ultimate  adoption 
of  the  element  system  for  reporting  the  analysis  of  fertilizers,  soils,  ash,  etc." 

"  That  the  suggestion  of  the  committee  looking  toward  the  ultimate  adoption 
of  the  element  system  be  approved,  but  that  no  state  should  discontinue  the  use  of 
the  terms  now  in  use  until  such  discontinuation  is  also  approved  by  this  associa- 
tion, and  that  meanwhile  the  subject  should  be  brought  before  the  International 
Congress  of  Applied  Chemistry  in  an  effort  to  secure  international  agreement." 

NOTE.  —  In  the  author's  opinion,  international  agreement  will  never  be  secured, 
judging  from  the  systems  in  vogue  for  money,  weights  and  measures,  etc.  If  secured, 


6oo  APPENDIX 

of  Official  Agricultural  Chemists  (1907),  page  100,  Bulletin  116,  of  the. 
Bureau  of  Chemistry,  United  States  Department  of  Agriculture.) 

AN  ACT  to  prevent  fraud  in  the  manufacture  and  sale  of  commercial 
fertilizers. 

SECTION  i.  Be  it  enacted  by  the  people  of  the  State  of repre- 
sented in  the  General  Assembly:  That  any  person  or  company  who  shall 
offer,  sell,  or  expose  for  sale,  in  this  State  any  commercial  fertilizer,  the 
price  of  which  exceeds  five  dollars  a  ton,  shall  affix  to  every  package  in  a 
conspicuous  place  on  the  outside  thereof,  or  furnish  to  the  purchasers  of 
goods  sold  in  bulk,  a  plainly  printed  certificate,  naming  the  materials, 
including  the  filler  (if  any),  of  which  the  fertilizer  is  made,  stating  the 
name  or  trade-mark  under  which  the  article  is  sold,  the  name  of  the  manu- 
facturer and  the  place  of  manufacture,  and  a  chemical  analysis,  stating 
only  the  minimum  percentages  of  nitrogen  in  available  form,  of  potassium 
soluble  in  water,  of  phosphorus  in  available  form  (soluble  or  reverted), 
and  of  insoluble  phosphorus,  the  analyses  to  be  made  in  accordance  with 
the  methods  adopted  by  the  Association  of  Official  Agricultural  Chemists 
of  the  United  States. 

SECTION  2.  Before  any  commercial  fertilizer  is  sold,  or  offered  for 
sale,  the  manufacturer,  importer,  or  party  who  causes  it  to  be  sold,  or 

offered  for  sale,  within  the  State  of  —  —  shall  file  in  the  office  of  the 

State  Board  of  Agriculture,  a  certified  copy  of  the  certificate  referred  to 
in  Section  i  of  this  ACT,  and  shall  deposit  with  the  secretary  of  the  said 
Board  of  Agriculture  a  sealed  glass  jar,  containing  not  less  than  one  pound 
of  the  fertilizer,  accompanied  with  an  affidavit  that  it  is  a  fair  average 
sample. 

SECTION  3.  The  manufacturer,  importer,  or  agent  of  any  commercial 
fertilizer  exceeding  five  dollars  per  ton  in  price,  shall  pay,  annually, 
a  license  fee  of  twenty-five  dollars  for  each  one  thousand  tons  (or  fraction 
thereof)  of  said  fertilizer,  for  the  privilege  of  selling  or  offering  for  sale, 

it  would  be  a  matter  of  some  convenience  to  scientists,  but  of  little  or  no  practical 
value  to  American  agriculture.  The  fertilizer  laws  of  some  states  (at  least  of 
Kansas  and  Illinois)  already  require  fertilizer  guarantees  to  be  made  on  the  basis 
of  the  actual  plant-food  elements;  and  the  agricultural  experiment  stations  of  some 
other  states  (at  least  of  Ohio,  Iowa,  Nebraska,  and  South  Dakota)  now  report  the 
results  of  soil  investigations  in  terms  of  the  elements. 

The  use  of  the  simple  element  system  is  of  great  value  to  any  state,  even  though 
all  adjoining  states  continue  to  use  the  complex  systems,  which  require,  for  exam- 
ple, that  the  potassium  in  potassium  chlorid  (K.C1)  shall  be  reported  in  terms  of 
potash  (KgO)  and  that  the  calcium,  even  in  acid  soils,  shall  be  reported  in  terms  of 
quicklime  (CaO). 


APPENDIX  601 

within  the  State,  during  the  calendar  year,  said  fee  to  be  paid  to  the  treas- 
urer of  the  -  -  State  Board  of  Agriculture:  Provided,  that  whenever 
the  manufacturer  or  importer  shall  have  paid  the  license  fee  herein  re- 
quired, any  person  previously  certified  to  the  Office  of  the  State  Board 
of  Agriculture  to  be  an  authorized  agent  for  such  manufacturer  or  im- 
porter shall  not  be  required  to  pay  the  fee  named  in  this  section. 

SECTION  4.  All  analyses  of  commercial  fertilizers  sold  within  the 
State,  shall  be  under  the  direction  of  the  State  Board  of  Agriculture,  and 
paid  for  out  of  funds  arising  from  license  fees,  as  provided  for  in  Section  3. 
At  least  one  analysis  of  each  fertilizer  shall  be  made  annually,  from  a 
sample  collected  in  the  open  market. 

SECTION  5.  Any  person  or  party  who  shall  offer  or  expose  for  sale  any 
commercial  fertilizer  without  complying  with  the  provisions  of  Sections 
i,  2,  and  3  of  this  Act;  or  shall  permit  an  analysis  of  such  fertilizer 
to  be  furnished,  stating  that  it  contains  a  larger  percentage  of  any  one 
or  more  of  the  constituents  named  in  Section  i  of  this  Act,  than  it  really 
does  contain,  shall  be  fined  not  less  than  two  hundred  dollars  for  the 
first  offense,  and  not  less  than  five  hundred  dollars  for  every  subsequent 
offense;  and  the  offender,  in  all  cases,  shall  also  be  liable  for  damages 
sustained  by  the  purchaser  of  such  fertilizer:  Provided,  however,  that  a 
deficiency  of  one  half  per  cent  of  the  nitrogen,  potassium,  or  phosphorus 
claimed  to  be  contained,  shall  not  be  considered  as  evidence  of  fraudulent 
intent. 

SECTION  6.  Suit  may  be  brought  for  the  recovery  of  fines  or  damages 
under  the  provisions  of  this  ACT,  in  the  county  where  the  fertilizer  was 
offered  for  sale,  or  where  it  was  manufactured ;  and  all  fines  so  recovered, 
shall  be  paid  into  the  treasury  of  the  State  Board  of  Agriculture  by  the 
court  collecting  the  same.  The  treasurer  of  the  State  Board  of  Agri- 
culture, after  payment  of  expenses  for  collecting  and  analysis,  and  the 
publication  of  the  annual  report  relating  to  the  analysis,  use,  and  results 
obtained  from  fertilizers,  shall  on  or  before  the  first  day  of  July  pay  into 
the  treasury  of  the  State  any  surplus  remaining  in  his  hands,  on  account 
of  license  fees  and  fines,  received  during  the  previous  calendar  year 
through  the  provisions  of  this  Act. 

SECTION  7.  The State  Board  of  Agriculture  shall  publish,  annu- 
ally, a  correct  report  of  all  analyses  made  and  certificates  filed,  together 
with  a  statement  of  moneys  received  on  account  of  license  fees  and  fines, 
and  expended  for  analyses  and  publication  of  the  report  relating  to 
fertilizers. 

SECTION  8.  The  officers  and  members  of  the  State  Board  of 

Agriculture  or  any  person  authorized  by  said  board  is  hereby  empowered 


602 


APPENDIX 


to  select  from  any  lot  or  package  of  commercial  fertilizers  exposed  for 

sale  in  any  county  of ,  a  quantity  not  exceeding  two  pounds,  which 

quantity  shall  be  for  analysis  to  compare  with  the  sample  deposited  with 
the  secretary  of  said  Board  of  Agriculture,  as  provided  for  in  Section  2 
of  this  Act,  and  with  the  printed  certificate  described  in  Section  i. 

SECTION  9.  All  suits  for  the  recovery  of  fines,  under  provisions  of  this 
Act,  shall  be  brought  by  the  Attorney-general  of  the  State  in  the  name 
of  the  people  of  the  State  of . 

In  some  states  fertilizers  can  be  sold  only  with  tags  or  certificates  pur- 
chased in  advance  from  the  State  Board  of  Agriculture  or  other  official 
control.  The  certificates  may  be  issued  in  different  denominations,  as 
lo-ton  tags,  i -ton  tags,  and  o.i-ton  tags,  at  a  fixed  tax  per  ton,  which 
may  amount  to  as  much  as  25  cents  per  ton  (in  South  Carolina,  for 
example), 


SECTION   III 

TABLE   i2ifl.    COMPOSITION  OF  ANIMAL  PRODUCTS,  WASTE, 
LITTER,   AND  ASHES 

(Pounds  in  1000  of  the  Material) 


MATERIAL 

DRY 

MATTER 

NITROGEN 

PHOSPHORUS 

POTASSIUM 

CALCIUM 
CARBONATE 

Dead  animals,  ground  .     . 
Flesh  meal    

95° 
720 
880 
850 
850 

TOO 

65 
228 

37 
420 

850 
850 
900 
900 

850 
850 
200 

87*5 
700 

65.0 
97.0 
81.0 
S4-o 
92.0 

6-5 

7.0 

IO.O 

6.0 
13-6 

14.7 

J7-5 
10.4 

5-8 

IO.O 

8.8 

2-3 

61.6 

27-S 
56.8 

•3 
.8 

I.O 

i.i 
4-8 
•7 
•     5-3 

1.8 

J-7 
.6 
.6 

•9 
.8 
.r 

5-° 
5-o 
i-5 
•5 

2-5 
5-8 

2.0 
46.5 

1.6 

i-7 
J-7 

2.1 

i-7 
5-8    . 

10.4 

I  I.O 

6.6 
i.i 

2.8 

.6 
i.i 

50.0 

IO.O 

3-° 

I.O 

500 
400 

Fish  meal      

Wool,  unwashed   .... 
Wool,  washed  

Buttermilk    

Human  manure  (mixed),  fresh 
Human  solid  excrement,  fresh 
Human  urine,  fresh   .     .     . 
Chicken  manure,  fresh  .     . 

Red  clover  straw   .     .     .     .  ' 
Soy  bean  straw      .... 
Peanut  hulls      

Rice  hulls      .... 

Oak  leaves   

Pine  needles  

Apple  pomace  

Wood  ashes,  unleached 
Wood  ashes,  leached     .     . 
Coal  ashes  (soft)  .... 
Coal  ashes  ^hard)      .     .    . 

APPENDIX 


603 


TABLE  1216.     COMPOSITION  OF  PLANTS  AND  PLANT  PRODUCTS 
(CHIEFLY  AFTER  VON  WOLFF,    1889) 
(Pounds  in  1000  of  Produce) 


PRODUCE 

M 

|E 

°a 

NITROGEN 

PHOS- 
PHORUS 

POTAS- 
SIUM 

MAGNE- 
SIUM 

CALCIUM 

SULFUR 

SILICON 

g 
§ 

C/3 

CHLORIN 

<% 
&« 

SEEDS  OF  CEREALS 
Corn  (Maize)    .     .     . 
Oats    

850 

Sro 

16.0 

17  6 

2-5 

3.0 

3-i 

i.i 

0.2 

0.04 

O.I 

0.07 

O.2 

12.4 

Wheat      

geo 

20  8 

3.4 

16  8 

Rye      

850 

17  6 

1  7 

A    g 

8 

Barley       
Millet  

8S0 

gro 

16.0 

3-4 

2.8 

3-9 

1.2 

0.4 

0.2 

2.7 

0.4 

O.2 

22.3 

Rice,  hulled  .... 
Sweet  corn     .... 

8S0 
1  80 

10.5 

4.6 

0.8 
o-3 

0.7 

2.0 

SEEDS  OF  LEGUMES 
Soy  bean  

8  co 

28  i 

Pea      

8«;o 

ic  8 

->  6 

8  j. 

o  8 

Red  clover    .... 
Horse  bean,  Vicia  .     . 
Garden  bean      .     .     . 
Peanut  kernels  .     . 

85o 
850 
85o 
85o 

3°-S 
40.8 
39-o 
38-0 

6.3 

5-3 
4.2 

3-3 

"•3 

10.7 

IO.I 

7.0 

3-° 
i-3 
i-3 

1.8 
i.i 
i.i 

0.4 
0.4 
0.4 

0.2 
O.O9 
O.O9 

0.3 

0.3 

°-3 

°-5 
o-5 
°-3 

38.3 
31.0 
27.4 

OIL  SEEDS 
Cotton      

850 

-16  f. 

4.2 

8.4 

3.1 

1.2 

O.I 

O.O4 

T   6 

0.5 

11.8 

Flax     

850 

12.8 

5.7 

8.0 

2-7 

1.8 

O.I 

O.2 

0.5 

32.6 

Hemp       

850 

26.1 

7-i 

7.6 

i-S 

7-5 

0.04 

2-5 

0-3 

46.3 

STRAW 
Corn  (Maize)    .     .     . 
Oat      

850 
850 

4.8 
c.6 

i-7 

1.2 

13-7 
13.5 

1.6 
1.4 

3-5 

I.O 

I.O 

0.6 

6.2 

11.4 

0.4 
i.e. 

0.6 

2-7 

45-3 
61.6 

Wheat  

850 

4.8 

I.O 

5-2 

0.7 

I.O 

0.4 

14.4 

0.4 

n  8 

46  o 

Rye      

850 

4.0 

I.I 

7.1 

0.7 

2.2 

0.6 

8.8 

o.c 

o  8 

18.2 

Barley       
Buckwheat    .... 

850 
850 

6.4 

13.0 

0.8 

2-7 

8.8 
20.4 

°-7 

1.2 

*'3 
6.9 

0.7 
i.i 

10.90 
1-4 

1.2 

0.8 

i-5 

4.1 

45-9 
Si-7 

COBS  AND  CHAFF 
Corncobs       .... 
Oat  chaff       .... 
Wheat  chaff  .... 
Rye  chaff       .... 

850 
850 
850 
850 

2-3 
6.4 
7.2 
5-8 

0.09 
0.6 

i-7 
2.4 

1.9 

3-7 
6.9 

4-3 

O.I 
0.9 
0.7 
0.7 

O.I 
2.8 
1.2 
2-5 

0.04 
1-4 

0.04 

0.6 
23-S 
34-8 
30-9 

0.07 

2.1 

i-3 

O.2 

O.2 

0.8 
0.4 

4-5 
71.2 
92.0 
82.7 

HAY 
Redtop  

850 

IO-5 

i.e 

8.0 

Red  clover  in  flower  . 
Alsike  clover      .     .     . 
Alfalfa,  early  bloom    . 
Red  clover,  ripe 
Red  clover,  in  bud 
Red  clover,  young  .     . 
White  clover  in  flower 
From  very  young  grass 

850 
850 
850 
850 
850 
850 
850 
850 

19.7 
24.0 
23.0 

12.  S 

24-5 

35-5 
23.2 

2S-S 

2-5 

1.8 

2-3 

1.9 
3-i 
4-5 
3-5 

3-2 

iS-7 
9-4 
12.3 

8-3 

21-5 

2S-3 
ii.  i 
26.3 

3-9 
3-i 
1.9 
4.2 
4-7 
4-7 
3-6 

2.8 

14.6 
9.8 

18.2 
"•3 
IS-* 
17.1 

13-3 
7.2 

0.8 
0.6 

i-5 
0.6 
0.7 
0.7 
1.8 
i.i 

0.8 
0.8 

2.8 

1.4 
0.9 

1.2 

i-3 

7.5 

0.8 
0.9 
0.8 

I.O 

I.I 

1.4 
3-3 

I.O 

2.2 
2.2 
1.9 
!-3 

2-4 

3-3 

2.6 

8.4 

57-6 
40.0 
62.0 
44-7 
68.4 
82.3 
61.1 
82.4 

GRASSES 
Timothy  
Rye  grass      .... 
Orchard  grass    .     .     . 
Rich  pasture  grass 

300 
300 
300 
218 

5-4 
5-7 

7-2 

I.O 
I.O 

0.6 
0.8 

5-9 
5-9 
4-9 
6.8 

0.4 

0.2 

0-3 
0.7 

1.2 
I.I 

0.8 
1.9 

O.2 

°-3 

0.2 

o-3 

3-i 
3-i 

2.8 

1.9 

«-3 

o-5 
0.6 

O.2 

i.i 

2.1 

i-3 

2.1 

20.5 
20.4 
17.8 

21.  1 

604 


APPENDIX 


TABLE   i2ift.    COMPOSITION  OF   PLANTS  AND  PLANT  PRODUCTS 
(CHIEFLY  AFTER  VON  WOLFF,   1889)—  Continued 

(Pounds  in  1000  of  Produce) 


M 

>s 

i 

o 

A§ 

~ 

gs 

S 

g 

H 

§ 

1 

2 

M 

PRODUCE 

SB 

i 

Is 

H  £ 

og 

S 

H) 

§ 

s 

O 
»J 

5  5 

W  ^ 

S 

PI  9 

Si  ^ 

'S  " 

< 

D 

1 

o 

• 

^ 

* 

fc 

A. 

2 

u 

c« 

Cfl 

C0 

U 

LEGUMES 

Red  clover,  young  .     . 

140 

6.0 

O.? 

4-3 

0.8 

2.8 

O.I 

0-9 

O.2 

0.6 

14.0 

Red  clover  in  bud   .     . 

180 

5-3 

o-7 

4-6 

I.O 

3-2 

0.2 

O.2 

O.2 

0.5 

14.7 

Red  clover  in  flower  . 

200 

4.8 

0.6 

3-7 

0.9 

3-4 

O.2 

O.2 

O.2 

0.5 

Alsike  clover      .     .     . 

1  80 

5-3 

0.4 

2.O 

°-7 

2.1 

O.2 

O.I 

O.2 

°-S 

8^6 

Lucern,  or  alfalfa  .     . 

260 

7.2 

0.7 

3-8 

o-S 

6.1 

0.4 

0.8 

O.2 

0.6 

19.2 

White  clover  in  flower 

195 

S-6 

0.8 

2.6 

0.8 

3-r 

0.4 

0.3 

0.7 

0.6 

14-3 

FRUITS 

Apple,  entire  fruit 

169 

0.6 

O.I 

0.7 

O.I 

0.07 

0.4 

0.04 

0.4 

2.2 

Pear,  entire  fruit    .     . 

169 

0.6 

O.2 

O.I 

0.2 

0.08 

0.05 

O.2 

3-3 

Grape,  entire  fruit 

170 

1.7 

O.O6 

4-2 

O.2 

O.O7 

O.2 

O.I 

O.O/ 

O.I 

8.8 

Raspberries  .... 

1  80 

1.5 

2.1 

2-9 

Strawberries  .... 

IOO 

T-5 

o-S 

2-5 

ROOTS,  TUBERS,  BULBS 

Potato      

250 

-  . 

O.7 

4-8 

0.3 

O.2 

O.2 

o.oo 

O.2 

O  3 

9c 

Sugar  beets  .... 

i!6 

/ 
0.4 

3-2 

0.4 

O.I 

0.9 

0.4 

o-3 

•3 

Turnips    

80 

1.8 

O   7 

2.4 

O.  T 

°-5 

O.7 

o  c 

f\   A 

Rutabagas    .... 

2.1 

o-S 

2-9 

O.2 

0.6 

O 

°-3 

"•o 

°-3 

o-S 

7-5 

Artichoke      .... 

2OO 

3-2 

0.6 

3-9 

O.2 

O.2 

O.2 

0.9 

0.7 

0.4 

9.8 

Onion       

I4O 

2.7 

0.6 

2.1 

O.2 

i.r 

O.2 

0.3 

O.I 

O.2 

7-4 

Beets  

I2O 

1.8 

O.3 

4.O 

O.2 

O.2 

O.  I 

o.oo 

i.i 

_    _ 

Carrots     

150 

2.2 

*O 

2.? 

O.2 

0.6 

O.2 

o.oo 

T    1 

O  4 

9.1 

8.2 

Parsnip    

2O7 

5    A 

0.8 

J 

0.8 

O.2 

o.oo 

'O 
O.  I 

O  4 

Radish     

67 

•*t 

I  .O 

O.2 

1.7 

O.I 

O.I 

O.7 

"3 

A    O 

Horseradish  .... 

233 

*  -y 
4-3 

0.9 

O 

6.4 

0.2 

i  '4 

2.O 

0.7 

0.3 

0.3 

4-9 
19.7 

"VEGETABLES" 

Cabbage,  outer  leaves 

110 

2.4 

0.6 

4.8 

0.4 

2.0 

I.O 

0.05 

i.i 

!-3 

IS-6 

Cabbage,  heart       .     . 

IOO 

o-S 

3-6 

O.2 

0.9 

°-5 

0.05 

0.6 

°-5 

9.6 

Cucumber,  fruit     .     . 

44 

i!6 

2.O 

O.I 

o-3 

O.2 

0.2 

0.4 

0.4 

5-8 

Lettuce     

60 

0.3 

3.1 

O.I 

0.4 

O.I 

0.6 

0.6 

0.4 

8.1 

Asparagus,  sprouts     . 

67 

3-2 

0.4 

I.O 

O.I 

0.4 

O.I 

O.2 

°-7 

S-° 

Cauliflower,  heart  .     . 

96 

4.0 

0.7 

3-0 

O.2 

0.4 

0.4 

O.I 

0.4 

0.3 

8.0 

MISCELLANEOUS 

Wheat  flour  .... 

900 

22.O 

2-5 

4-5 

Wheat  bran  .... 

875 

25.0 

12.2 

13.0 

Gluten  meal  .... 

900 

50.0 

1.3 

0.4 

Hominy  feed      .     .     . 

900 

I6.3 

4-3 

4.0 

Peanut-kernel  cake     . 

900 

76.7 

8.7 

r2-5 

Soy-bean  cake   .     .     . 

900 

68.0 

IO.O 

15.0 

• 

Rape  cake     .... 

900 

50.0 

8.7 

10.8 

Linseed  cake     .     .     . 

850 

47-2 

6.8 

IO.I 

4.8 

3-° 

°-7 

2-9 

0.6 

0.4 

51.3 

Cotton-seed  cake   . 

850 

62.1 

12.7 

12.6 

5-9 

2.0 

0-3 

2-5 

66.4 

Tobacco  leaves  .     . 

850 

34.8 

3-° 

3S-4 

6-5 

37-5 

3-5 

4.0 

3-5 

9-4 

140.7 

Tobacco  stems  .     .     . 

850 

24.6 

4-2 

24-4 

o-3 

9-2 

0.9 

0.8 

5-1 

2.4 

64.7 

Flax  stalks    .... 

850 

1.8 

7.8 

1.2 

4.8 

0.8 

0.8 

1.8 

T-3 

31.1 

Hemp  stalks      .     .     . 

850 

0.9 

4-4 

1.2 

IT.4 

O.2 

1.4 

0.4 

0.6 

3x-7 

Hops,  entire  plant  .     . 

850 

25.0 

2-5 

14-7 

4.2- 

13-9 

1.2 

6.2 

1.4 

3-7 

72.9 

APPENDIX 
SECTION  IV 


605 


STATISTICS  OF  AGRICULTURAL  PRODUCTS1 

CROP  AREAS,  YIELDS,  AND  VALUES,  1908 

The  final  revised  estimates  of  the  Crop  Reporting  Board  of  the  Bureau 
of  Statistics,  United  States  Department  of  Agriculture,  based  on  the 
reports  of  the  correspondents  and  agents  of  the  Bureau,  supplemented 
by  information  derived  from  other  sources,  indicate  the  acreage,  produc- 
tion, and  value,  in  1908  and  1907,  of  important  farm  crops  of  the  United 
States  to  have  been  as  follows : 


CROP 

ACREAGE 
(Acres) 

PRODUCTION 

FARM  VALUE,  DEC.  i 

Per 

Acre 
(Bu.) 

Total 
(Bu.) 

Per 
Bushel 

Total 

Corn,  1908   .... 
1907   .... 

101,788000 
99,931000 

26.2 

25-9 

2,668,651000 
2,592,320000 

$0.606 
.516 

$1,616,145000 
i,336.9°i°o° 

Winter  wheat,  1908 
1907 

30,349000 
28,132000 

14.4 
14.6 

437,908000 
409,442000 

•937 
.882 

410,330000 
361,217000 

Spring  wheat,  1908 
1907 

17,208000 
17,079000 

13.2 
13.2 

226,694000 
224,645000 

.911 
.860 

206,496000 
193,220000 

Oats,  1908   .... 
1907   .... 

32,344000 
31,837000 

25.0 
2.3-7 

807,156000 
754,443°°° 

.472 
•443 

381,171000 
334,568000 

Barley,  1908  .... 
1907  .... 

6,646000 
6,448000 

1,948000 
1,926000 

803000 
800000 

25-1 
23.8 

16.4 
16.4 

19.8 
17.9 

166,756000 
153.597°°° 

31,851000 
31,566000 

15,874000 
14,290000 

•554 
.666 

.736 
•731 

.756 
.698 

92,442000 
102,290000 

33.455°oo 
23,068000 

12,004000 
9,975000 

IOO7  . 

Buckwheat,  1908  .  . 
1907   .  . 

Flaxseed,  1908  .  .  . 
1907  .  .  . 

Rice,  1908  

2,679000 
2,864000 

655000 
627300 

9.6 
9.0 

33-4 
29.9 

25,805000 
25,851000 

21,890000 
18,738060 

1.184 
•956 

.812 
•858 

30,577000 
24,713000 

17,771000 
16,081000 

1907   .... 

Potatoes,  1908  .  .  . 
1907  .  .  . 

3,257000 
3,124000 

85-7 
95-4 

278,985000 
297,942000 

.706 
.617 

197,039000 
183,880000 

Hay,  1908   .... 
i9°7  

46,486000 
44,028000 

2  J-S2 
*i-45 

2  70,798000 
2  63,677000 

3  8.98 
3  n.  68 

635,423000 
743.5°7°°o 

Tobacco,  1908  .  .  . 
1907  .  .  . 

875000 
820000 

4  820.2 
4  850.5 

4  718,061000 
4  698,  126000 

'.103 

5.102 

74,130000 
71,411000 

1  Figures  furnished  by  the  Bureau  of  Statistics,   United  States  Department  of 
Agriculture,  except  where  otherwise  credited. 

2  Tons.  *  Per  ton.  *  Pounds.  6  Per  pound. 


6o6 


APPENDIX 


CORN 

AVERAGE  YIELD  PER  ACRE  OF    CORN  IN  THE  UNITED  STATES  (WITH 
TOTALS  FOR  1909) 


STATE  OR  DIVISION 

10-  YEAR  AVERAGES 

1006 

1907 

Bu. 

37-0 
35-o 
36.0 
36.0 
31-2 
33-o 
27.0 
31-5 
32.5 

1908 

1909 

1910 

CROP  or  1909 

1866- 
1875 

1876- 
1885 

1886- 
1895 

1896- 
I9°S 

Maine       .    ._  .    .    . 
New  Hampshire     .    . 
Vermont  
Massachusetts   .     .     . 
Rhode  Island     .     .     . 
Connecticut  .... 
New  York     .... 
New  Jersey  .... 
Pennsylvania     .    .    . 
North  Atlantic 

Delaware      .... 
Maryland      .... 
Virginia    
West  Virginia    .    .    . 
North  Carolina       .     . 
South  Carolina  .    .    . 
Georgia    
Florida     
South  Atlantic  .    . 

Ohio    
Indiana    
Illinois      
Michigan       .... 
Wisconsin     .... 
Northeast  Central 

Minnesota     .... 
Iowa    
Missouri  
North  Dakota    .     .     . 
South  Dakota    .     .     . 
Nebraska      .... 
Kansas     
Northwest  Central 

Kentucky      .... 
Tennessee     .... 
Alabama  
Mississippi    .... 
Louisiana      .... 
Texas  
Oklahoma     .... 
Arkansas  
South  Central   .     . 

Bu. 
29-3 
35-5 
36.0 
34-6 
26.9 
3°-9 
31-6 
36.5 
35-1 

Bu. 

33-8 
35-5 
35-3 
32-S 
30.8 
29.1 
30-4 
32.8 
32.6 

Bu. 

34-3 
34-5 
35-5 
35-7 
31-2 
33-4 
31-1 
30-9 
30.4 

Bu. 

35-1 

34-0 
35-1 
35-9 
31-9 
35-8 
30.3 
34-3 
34-5 

Bu. 

37-0 
37-5 
35-5 
39-7 
33-1 
40.0 
34-9 
36.3 
40.2 

38^3" 

Bu. 

40.5 
39-0 
4°-3 
40.4 
42.8 
41-3 
38.8 
38.0 
39-  S 
39-3 

Bu. 

38.0 
35-1 
37-o 
38.0 
33-2 
41.0 
36.0 
32.7 
32.0 

Bu. 

46.0 
46.0 
43-o 
45-5 
40.0 
53-2 
38-3 
36.0 
41-0 
4°-3 

Acres 
17000 
30000 
65000 
47000 

IIOOO 

60000 
670000 
290000 
1,525000 

Bushels 

646000 
1,053000 
2,405000 
1,786000 
365000 
2,460000 
24,120000 
9,483000 
48,800000 

34-2 

32.0 

30.9 

33-5 

3JJ 

33-6 

2,715000 

91,118000 

20.5 
24-7 

2O.O 
29-3 
14-3 

9-7 
ii-3 
10.9 

22.5 
26.0 
17.9 
25.8 
13-3 
8.8 
10.3 
9-5 

19.8 
23-5 
17.4 
22.2 
12.4 
IO.2 
II.  2 
IO.2 

26.8 
32.0 

2I.O 
26.4 
13-4 
9-5 
10.5 
9-3 

30.0 
35-0 
24-3 
30-3 
15-3 
12.2 
I2.O 
II.O 

27-5 
34-2 
25-0 
28.0 
16.5 
iS-i 
13.0 
1  1  -3 

32.0 
36.6 
26.0 
31-2 
18.0 
14.1 
12.5 
10.5 

18.3 

31-0 
31-4 
23.2 
31-4 
16.8 
16.7 
13.0 

12.6 

31.8 
33-5 
25-5 
26.0 
1  8.  6 
18.5 
14-5 
I3-Q 
19.4 

2000OO 

700000 
2,040000 
880000 
2,898000 
2,218000 
4,400000 
665000 

6,200000 

21,980000 
47,328000 
27,6-52000 

48,686000 
37,041000 

61,160000 

8,379000 

17.4 

14.4 

13-9 

15.0 

16.9 

17.8 

18.5 

14,001000 

258,406000 

35-3 
32.3 
29.9 
32.2 
31-4 

32.6 
29-9 
27.2 
31-8 
30.4 

28.8 
28.9 
29.0 
26.7 
27.4 

34-8 
34-0 
34-5 
32.2 
33-2 

42.6 

30.6 

36.1 

37-o 
41.2 

34-6 
36.0 
36.0 
30.1 
32.0 

38.5 
3°-3 
31-6 
31-8 
33-7 

39-5 
40.0 
35-9 
35-4 
33-0 

36.5 
39-3 
39-1 
32.4 
32.5 

3,875000 
4,913000 
10,300000 
1,976000 
1,533000 

153,062000 
196,520000 
369,770000 
69,950000 
50,589000 

31.9 

29.2 

28.7 

34-2 

38.4 

35-o 

32-7 

37-2 

37-7 

22,597000 

839,891000 

32.2 

34-3 
30.1 

32.S 
33-5 

30.9 
31-8 
28.6 

35-5 
33-4 

27-6 

30.1 
27.7 
20.  i 
16.8 
25.2 

22.2 

29.1 
32-4 
27.4 

22.6 

25.8 

28.0 

22.O 

33-6 
39-5 
32.3 
27.8 
33-5 
34-1 

2.H.O 

34-1 

27.0 
29-5 
31-0 
20.  o 
25-5 
24.0 

22.1 

~26T8 

29.0 

31-7 
27.0 
23.8 
29-7 
27.0 
22.O 

34-8 
3i-5 
26.4 
3i.o 
3i-7 
24.8 
19.9 

26.7 

32.7 
36.3 
33-0 
14.0 
25.0 
25.8 
19.0 

IsTs 

1,690000 
9,200000 
8,100000 
195000 
2,059000 
7,825000 
7,750000 

58,812000 
289,800000 
213,840000 
6,045000 
65,270000 
194,060000 

154,225000 

32.4 

31-4 

26.1 

27.7 

27.4 

36,819000 

982,052000 

29-3 
22.9 
14.0 
16.0 
18.2 
23-7 

25-7 

26.0 
21.4 
12.4 
14.2 
16.3 
19.8 

21.4 

24-9 
21-5 
12.8 
14.7 

16.2 

I9.O 
19.2 

25-5 
21.9 
12.6 

14.7 

16.3 

17.7 
23.5 

17.8 

33-0 
28.1 
16.0 
18.5 
17.2 
22.5 
33-3 
23-6 
24.8 

28.2 
26.0 
15-5 
17.0 
17-5 
2I.O 
24.4 
17-2 

25.2 
24.8 
14.7 
17-3 
19.8 
25-7 
24.8 
20.  2 

29.0 

22.  0 
13-5 
14-5 
23.0 
15.0 
17.0 

18.0 
18.3 

29.0 
25-9 

1  8.0 
20.5 
23.6 

2O.6 

16.0 
24.0 

21.5 

3,568000 

3,575000 
3,233000 
2,810000 
2,226000 
8,150000 
5,950000 
2,800000 

103,472000 
78,650000 
43,646000 
40,745000 

51,198000 
122,250000 
101,150000 
50,400000 

23-4 

19.7 

I9.I 

18.9 

21-5 

22.7 

32,312000 

591,511000 

29-S 
28.6 

26.6 

2S-3 

20.4 

21.  1 
23-3 
22.5 
26.4 
26.3 
29.2 

26.1 
23.6 
22.8 
20.7 
2O.2 
19.9 
24.2 
20.7 
24-3 
21).  0 

22.3 

24.7 

18.7 

23.2 
22.3 

23.8 

27.7 

20.  o 

23.8 

29.9 

23-4 
27.0 
27.9 
29.4 
29-5 
32.0 
28.3 
25-2 
27.6 
34-9 
29.6 

22.5 
25-0 
23-5 
29.O 

37-5 
25-5 
30.0 
27.0 
27-5 
34-Q 
27-5 

23-4 

28.0 

2O.2 
27.O 
33-2 
29.4 

2Q.O 
25-5 
27.8 
32.0 

25-3 

35-o 
28.0 
24.2 
31-3 
32.1 
31-4 
30.6 
27.8 
30.7 
34-8 
28.7 

23.0 

IO.O 

19.9 
23.0 
32.5 
30.3 
32.0 
28.0 
25-5 
37-5 
24.7 

5000 
5000 
135000 
68000 
13000 
13000 
6000 
15000 
17000 
50000 

175000 
140000 
3,267000 
2,128000 
417000 
408000 
180000 
417000 
522000 
1,740000 

Wyoming      .... 

New  Mexico.     .    .    . 
Arizona    

Utah    

Washington  .... 
Oregon     

California       .... 

Western    .    .     . 
United  States    .    . 

28.7 

25-6 

24-3 

23.1 

327000 

9,398000 

26.1 

25-5 

23-4 

25.2 

30.3 

25-9 

26.2 

25-5 

27.4 

108,771000 

2,772,376000 

APPENDIX 


607 


CORN  —  Continued 

ACREAGE,  PRODUCTION,  VALUE,  PRICE,  AND  EXPORTS  OF  CORN  IN  THE  UNITED 
STATES,  1849-1909 


Year 

Acreage 

Aver- 
age 
yield 
per 
acre 

Production 

Aver- 
age 
farm 
price 
per 
bushel, 
Dec.  i 

Farm  value 
Dec.  i. 

Domestic 
exports, 
including 
corn  meal, 
fiscal  year 
beginning 
July  i 

Per 
Cent 
of 
Crop 
ex- 
port- 
ed 

Acres 

Bu. 

Bushels 

Cents 

Dollars 

Bushels 
7  632860 

P.cl. 

1866     

867,946295 

47.4 

1.8 

J86?     

23.6 

768,320000 

57.0 

437,769763 

1.6 

1868          

34  887246 

006,527000 

46.8 

8,286665 

!869     

874,320000 

59.8 

1870     

28.3 

1,094,255000 

49.4 

1871     

991,898000 

43.4 

3-6 

1872     

30.8 

X873     

23.8 

932,274000 

44.2 

1874 

850,148500 

58.4 

1875     

1,321,069000 

36.7 

484,674804 

j876          

1,283,827500 

1877     

1,342,558000 

34.8 

6.5 

^78     

1,388,218750 

87  884892 

6.3 

1879     

1,547,001790 

37-5 

580,486217 

6.4 

I88o     

27.6 

1,717,434543 

1881     
1882     

64,262025 

18.6 

1,194,916000 

63-6 
48.5 

759,482170 
783  867175 

44,340683 

3-7 

2.6 

!883     

68  301889 

46,258606 

!884          

69  683780 

2<;.8 

1885               .... 

32.8 

1886     

36.6 

41  368584 

1887     

!888     

3.6 

1889     
1890     

78,319651 

27.0 

2,112,892000 

28.3 

597,918829 

103,418709 

4-9 

1891     
1892     

76,204515 

27.0 

2,069,154000 

40.6 

836,439228 

76,602285 

3-7 

1893     
1894     

1895     

72,036465 
62,582269 

22-.S 
19.4 

26.2 

1,619,496131 
1,212,770052 

36.5 
45-7 

591,625627 
554,719162 

66,489529 
28,585405 

4-1 
2.4 

1896     

28  2 

7  8 

1897     

1898     

24.8 

28.7 

1899     

82,108587 

86 

1901     
1902     

91,349928 
94.043613 

I6.7 
26.8 

1,522,519891 
2,523,648312 

60.5 
4°-3 

921,555768 
1,017,017349 
952  868801 

28,028688 
76,639261 

1.8 
3-o 

2.6 

26  8 

1905     

28.8 

86  368228 

1907     

si.6 

1908     

60  6 

37,665040 

1909     

38,128498 

1.4 

1  Census  figures  of  production. 


6o8 


APPENDIX 


CORN—  Continued 
CORN  CROP  OF  COUNTRIES  NAMED,  1902-1906 


COUNTRY 

19O3 

(Bu.) 

1903 

(Bu.) 

19O4 

(Bu.) 

19O5 

(Bu.) 

19O6 

(Bu.) 

United  States      .     . 
Canada  (Ontario)   . 
Mexico      .... 
Total  No.  America 
Argentina       .     .     . 
Total  So.  America 
Austria-Hungary     . 
France       .... 
Italy          .... 

2,523,648000 
21,159000 
78,009000 

2,244,177000 
30,211000 
90,879000 

2,467,481000 
20,880000 
88,131000 

2,707,994000 
21,582000 
85,000000 

2,927,416000 
24,745000 
70,000000 

2,622,906000 

2,365,267000 

2,576,492000 

2814,576000 

3,022,161000 

84,018000 

148,948000 

175,189000 

140,708000 

194,912000 

89,944000 

J55.  355ooo 

179,701000 

146,369000 

198,984000 

139,126000 
24,928000 
71,028000 
16,000000 
68,447000 
48,419000 
25,272000 

183,994000 
25,360000 
88,990000 
14,000000 
80,272000 
50,464000 
18,759000 

89,757ooo 
19,482000 
90,545000 
15,000000 
19,598000 
25,920000 
21,300000 

i39>307ooo 
24,030000 
97,265000 
16,000000 
59,275000 
33,33  1000 
31,880000 

215,636000 
14,581000 
93,007000 
16,000000 
130,546000 
70,501000 
30,000000 

Portugal    .... 
Roumania      .     .     . 
Russia  (European)  . 
Spain    

Total  Europe 
Africa  

429,716000 

504,154000 

303,858000 

442,168000 

618,0517000 

36,899000 
7,256000 

36,118000 
4,987000 

38,862000 
9,972000 

37,6550°° 
8,374000 

37,700000 
8,608000 

Australia  .... 
New  Zealand      .     . 
Total  Australasia 
Grand  total     .     . 

590000 

627000 

547000 

506000 

653000 

7,846000 

5,614000 

10,519000 

8,880000 

9,261000 

318,7311000 

3,066,508000 

3,109,432000 

3,449,648000 

3,886,163000 

CORN,  AVERAGE  YIELDS  PER  ACRE,  BUSHELS 


YEARS 

SOUTH 
CAROLINA 

GEORGIA 

IOWA 

ILLINOIS 

UNITED  STATES 

1866-1875  (10  years) 
1876-1885  (10  years) 
1886-1895  (10  years) 
1896-1905  (10  years) 

9-7 
8.8 

10.2 

9-5 

"•3 
io-3 

II.  2 

10.5 

34-3 
31-8 
30-1 
32-4 

29.9 
27.2 
29.0 

34-5 

26.1 
25-5 
23-4 
25-2 

1866-1885  (20  years) 
1886-1905  (20  years) 

9-3 
9-9 

10.8 
10.8 

33-o 
31.2 

28.6 
3i-7 

25-8 
24-3 

1866-1905  (40  years) 

9.6 

10.8 

32.1 

30.1 

25.0 

CORN,  SINGLE-YEAR  RECORDS 


1899,  bu.  per  acre 

9.0 

IO.O 

31.0 

36.0 

25-3 

1909,  bu.  per  acre 

16.7 

13-9 

3i-5 

35-9 

25-5 

1899,  acres  of  corn 

1,857000 

3,249000 

7,815000 

6,865000 

82,109000 

1909,  acres  of  corn 

2,218000 

4,400000 

9,200000 

10,300000 

108,771000 

1899,  bu.  of  corn 

16,713000 

32,495000 

242,250000 

247,150000 

2,078,000000 

1909,  bu.  of  corn 

37,041000 

61,160000 

289,800000 

369,770000 

2,772,360000 

1899,  price  per  bu. 

450 

490 

350 

360 

37.20 

1909,  price  per  bu. 

9°0 

86^ 

490 

520 

59-60 

1899,  value  of  crop 

$  8,357000 

$16,247000 

$55,  7  17000 

$64,259000 

$    629,210000 

1909,  value  of  crop 

33,337ooo 

52,598000 

142,062000 

192,280000 

1,652,822000 

APPENDIX 


609 


INTERNATIONAL  TRADE  IN  CORN,  INCLUDING  CORN  MEAL,  1902-1906 

GENERAL  NOTE.     Substantially  the  international  trade  of  the  world. 

The  exports  given  are  domestic  exports  and  the  imports  given  are  imports  for 
consumption,  as  far  as  it  is  feasible  and  consistent  so  to  express  the  facts.  While 
there  are  some  inevitable  omissions  from  such  a  table  as  this,  on  the  other  hand, 
there  are  some  duplications  because  of  reshipments  that  do  not  appear  as  such  in 
official  reports.  For  the  United  Kingdom  import  figures  refer  to  imports  for  con- 
sumption. 

EXPORTS 


COUNTRY 

YEAR 
BEGIN- 
NING 

1902 

(Bu.) 

1903 

(Bu.) 

19O4 

(Bu.) 

1905 

(Bu.) 

1906 

(Bu.) 

Argentina       .     .     . 
Austria-Hungary     . 
Belgium    .... 
Bulgaria    .... 
Netherlands  .     .     . 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

46,959590 
3,010624 
4,346609 
7,883279 
4,726324 

82,845915 
310804 

6,579655 
5,089114 

5,373*94 

97,221783 
174342 
6,287688 
9,762657 
4,449009 

87,487629 
63218 
8,078215 
3,870090 
4,278515 

106,047790 
22361 

6,588557 
5,658500 
6,010176 

Roumania      .     .     . 
Russia       .... 
Servia        .... 
United  States     .     . 
Uruguay    .... 

Other  countries 
Total     .... 

Jan. 
an. 
Jan. 

July 
July 

43,013192 
44,148590 
1,091588 
76,639261 
703770 

1,528000 

31,080198 
25,349683 
171767 
58,222061 
1,004063 

1,086000 

18,042377 
18,633663 
130225 
90,293483 
2,002431 

1,009000 

1,441437 
7,372386 
806115 
119,893833 
28519 

4,100325 

1  23,394301 
29,878141 
1,755446 
86,367988 
2  034696 

23>547299 

234,050827 

217,112454 

248,006658 

237,420282 

250,205255 

IMPORTS 


Austria-Hungary  . 
Belgium  .... 
Canada  .... 
Cape  of  Good  Hope 
Cuba  

Jan. 
Jan. 
July 
}an. 
an. 

5,87497i 
14,583008 
7,i54522 
1,943896 
1.1^0176 

11,130274 
20,323863 

11,33353° 
3,471281 
610326 

14,090377 

I9,47433° 
I2,oo3574 
1,236927 
606  <;  1  7 

18,511368 
24,169780 
11,779679 
2,171601 

7,118221 
20,125507 
2  15,233894 
215007 

2  489087 

Denmark  .... 

Ecrvot  . 

Jan. 
Jan. 

^,355050 
51:266 

8,772022 

I4.2S37 

9,284777 

^•?OI7 

10,859257 

18,855752 

France  
Germany3  .  .  . 
Italy 

Jan. 
Jan. 
Jan. 

8,674931 

35,454243 
8,216902 

11,347114 
37,527343 

i  i;.oQ2<;27 

10,124353 
30,450853 

8.36SI2? 

11,122512 
36,538366 

c  OO287C 

14,509103 
44,883053 

8  666763 

Mexico  .... 
Netherlands  .  .  . 
Norway  .... 
Portugal  .... 
Russia  

Jan. 
Jan. 
Jan. 
Jan. 
Tan. 

142102 
I5,8i7237 
637387 
759967 
13^822 

496028 
20,160078 
765246 
366605 
41:7711: 

476182 
16,547198 

555991 
531889 
62CC2O 

1,454327 
16,234785 

544596 
2,724050 

2  2,079553 

25,305233 
718277 
*  2,724050 
*  4-27868 

Spain  

Jan. 

Sweden  .... 
Switzerland  .  .  . 
Transvaal  .  .  . 
United  Kingdom  . 

Jan. 
Jan. 
Jan. 
Jan. 

191958 
2,404644 
1,306038 
89,371445 

189357 
2,611202 
2,197476 
101,284919 

234986 
2,704457 
1,422985 
86,076697 

491035 
2,498380 

1,277353 
84,156490 

564946 
2,887291 

4  i,  277353 
97,736852 

3>309436 

7,42935! 

2  7,090991 

Total.     .     .     . 

—  —  — 

210,483315 

257,°9I403 

221,026621 

243,057067 

277,005211 

1  Average,  1902-1905. 

2  Preliminary. 


*  Not  including  free  ports  prior  to  March  i,  1906. 

*  Year  preceding. 


6io 


APPENDIX 


WHEAT 
WHEAT  CROP  OF  COUNTRIES  NAMED,  1903-1907 


COUNTRY 

19O3 

(Bu.) 

1904 

(Bu.) 

19O5 

(Bu.) 

19O6 

(Bu.) 

1907 

(Bu.) 

United  States     .     . 
Canada     .... 
Mexico     .... 
Total  No.  America 

Argentina      .     .     . 
Total  So.  America 

Austria-Hungary    . 
Belgium    .... 
Bulgaria   .... 
Denmark  .... 
France      .... 
Germany  .... 

Greece      .... 
Italy     

637,822000 
85,271000 
10,493000 

552,400000 
75,213000 
9,393000 

692,979000 
113,441000 
7,000000 

735,261000 
132,705000 
7,000000 

634,087000 
96,606000 
10,000000 

733,586000 

637,006000 

813,420000 

874,966000 

740,693000 

103,759000 

129,672000 

i5°,745°°° 

134,931°°° 

155,993000 

119,113000 

155.185000 

160,834000 

151,604000 

178,636000 

226,721000 
12,350000 
35,551000 
4,461000 
364,420000 
130,626000 

8,000000 
184,451000 
4,258000 
307000 
8,000000 

73,700000 
551,728000 
10,885000 
128,979000 
5,538000 

26,000000 
46,524000 

204,406000 
13,817000 
42,242000 
4,302000 
298,826000 
139,803000 

8,000000 
167,635000 
4,423000 

2I2OOO 
9,OOOOOO 

53.738°°° 
622,255000 
11,676000 

95-377°°° 
5,135000 

23,000000 
35,624000 

228,138000 
12,401000 
40,736000 
4,083000 
335,453°oo 
I35,947°°° 

8,000000 
160,504000 
5,109000 
329000 
5,000000 

103,328000 
568,274000 
11,280000 
92,504000 
5,529000 

20,000000 
57,422000 

268,675000 
12,964000 
55,076000 
4,161000 
324,919000 
144,754000 

8,000000 
176,464000 
4,978000 
303000 
9,000000 

113,867000 

45°,963°°° 
13,211000 
140,656000 
6,650000 

25,000000 
57,583000 

185,059000 
12,000000 
30,000000 
4,000000 
369,970000 
127,843000 

8,000000 

i?7,  543°°° 
5,000000 

200OOO 
6,OOOOOO 

42,237000 
455,OOOOOO 

8,375°°° 
100,331000 
5,953000 

16,000000 
53,860000 

Netherlands  .     .     . 
Norway    .... 
Portugal   .... 

Roumania     .     . 
Russia  (European) 
Servia  

Spain   

Sweden     .... 

Turkey  (European) 
England    .... 
Total     United 
Kingdom    .     . 

Total  Europe 

British  India,  includ- 
ing    such     native 
states  as  report  . 
Cyprus      .... 
Taoan  . 

50,321000 

39,082000 

62,188000 

62,481000 

58,275000 

1,830,526000 

1,747,262000 

1,803,132000 

1,826,422000 

1,616,086000 

297,601000 
2,477000 
9,600000 
69,659000 
35,000000 

359,936oo° 
2,176000 
19,754000 
44,494000 
35,000000 

283,063000 
2,441000 
18,437000 
68,011000 
35,000000 

320,288000 
2,410000 
20,283000 
57,427000 
35,000000 

315,386000 
2,000000 
22,932000 
56,000000 
35,000000 

Russia  (Asiatic) 
Turkey  (Asiatic)    . 
Total  Asia      .     . 

Algeria     .... 
Cape  of  Good  Hope 
EcrvDt  . 

430,516000 

477,550000 

423,152000 

451,586000 

447,518000 

34,035°°° 
1,755000 
12,000000 
4000 
294000 

7,523000 

25,484000 
2,000000 
12,000000 
7000 
486000 

10,510000 

25,579000 
2,000000 
12,000000 
4000 
483000 

5,720000 

34,080000 
2,000000 
12,000000 
8000 
542000 

4,409000 

31,120000 
2,000000 
12,000000 
6000 
500000 

6,000000 

Natal  

Sudan  (Anglo-  Egyp- 
tian)     .... 
Tunis  

Total  Africa  .     . 

Australia  .... 
New  Zealand     .     . 
Total  Australasia 
Grand  total    . 

55.61  1000 

50,406000 

45,705000 

53,030000 

51,626000 

12,768000 

7,69300° 

76,488000 
8,140000 

56,215000 
9,411000 

70,681000 
7,013000 

68,185000 
5,782000 

20,461000 

84,628000 

65,626000 

77,694000 

73,967000 

3,189,813000 

3,152,127000 

3,320,959000 

3,435,401000 

3,108,526000 

APPENDIX 


611 


WHEAT  —  Continued 

ACREAGE,  PRODUCTION,  VALUE,  PRICE,  AND  EXPORTS  OF  WHEAT  IN  THE  UNITED 
STATES,  1849-1909 


Year 

Acreage 

Aver- 
age 
yield 
per 
acre 

Production 

Aver- 
age 
farm 
price 
per 
bushel, 
Dec.  i 

Farm  value 
Dec.  i 

Domestic 
exports, 
including 
flour,  fiscal 
year 
beginning 
July  i 

Per 
cent 
of 
crop 
ex- 
ported 

Acres 

Bu. 

Bushels 

Cents 

Dollars 

Bushels 

P.ct. 

A  5944 

7-5 

1866     

9.9 

R  i 

1867     
1868     

J86Q     

18,321561 
18,460132 

1.6 

2.1 

3.6 

212,441400 
224,036600 

145.2 

108.5 

76.  q 

308,387146 
243,032746 

26,323014 
29,717201 

12.4 

13-3 

1870          

1871     

1.6 

I&J2      

1873      
1874      

22,171676 

2.7 

281,254700 

IO6.9 

86.3 

300,669528 

26  «;  ,881167 

91,510398 

32-5 

I8?S      
1876      

26,381512 

I.I 

292,136000 

89.5 
06  ^ 

261,396926 

74,750682 

25.6 

1877      

1878      

77.6 

•jc  ft 

1879      

3.8 

no.  8 

!88o     

498  549868 

1881     

ii  8 

1882     

3.6 

88.4 

1883     

1.6 

1884     

39,475885 

1885     

1886     

36,806184 

68.7 

•>•>  6 

1887     

68.1 

1888     

415,868000 

88,600743 

1889     

69.8 

1890     

83.8 

26  6 

1891     

83.9 

1892     

1893     
1894     

34,629418 
34,882436 

1.4 

396,131725 

53.8 

213,171381 

164,283129 

4i.5 

lgg5       

1896    

72.6 

1897     

so.s 

1898    

58.2 

1899     

58.4 

1901     

40,895514 

5-o 

748,460218 

62.4 

467*350156 

234,772516 

31.4 

637,821835 

18.9 

8.0 

74  8 

66.7 

1907     

87.4 

1908     

92  8 

114,268468 

•5.8 

87,364318 

1  Census  figures  of  production. 


6l2 


APPENDIX 


WHEAT  —  Continued 

AVERAGE  YIELD  PER  ACRE  OF  WHEAT  IN  THE  UNITED  STATES  (WITH 
TOTALS  FOR  1909) 


STATE  OR  DIVISION 

10-  YEAR  AVERAGES 

1006 

Bu. 

24.8 
22.3 

2O.O 
l8.3 

17-7 

18.2 

1007 

Bu. 
26.2 
23-0 
17-3 
18.5 
18.6 

I008 

Bu. 

23-5 
23.0 
17-5 
17-3 
18.5 

1909 

Bu. 

25.5 
25.0 

2I.O 
17.9 
17-0 
17.9 

I9IO 

Bu. 
29.7 
29-3 
23-7 
18.5 
17.8 

CROP  OF  1909 

1866- 
1875 

1876- 
1885 

1886- 
1895 

1896- 
1905 

Maine       
Vermont  
New  York     .... 
New  Jersey  .... 
Pennsylvania     .     .     . 
North  Atlantic 

Delaware      .... 
Maryland      .... 
Virginia    
West  Virginia    .     .     . 
North  Carolina       .     . 
South  Carolina  .    .     . 
Georgia    
South  Atlantic  .    . 

Ohio    
Indiana    
Illinois      
Michigan       .... 
Wisconsin     .... 
Northeast  Central 

Minnesota     .... 
Iowa    
Missouri  
North  Dakota    .     .     . 
South  Dakota    .     .     . 
Nebraska      .... 
Kansas     
Northwest  Central 

Kentucky      .... 
Tennessee     .... 
Alabama  
Mississippi    .... 
Texas  
Oklahoma     .... 
Arkansas  
South  Central   .     . 
Montana  .... 

Bu. 

13-2 
17.0 
14.1 
14.6 
13-3 

Bu. 
13-7 
16.8 
15-5 
13-3 
13-4 

Bu. 

15.8 
18.8 
15-4 
13-4 
:3-6 

Bu. 

22.1 
21.2 

17-5 

16.1 
15.8 

Acres 
9000 
1000 
420000 

IIOOOO 

1,545000 

Bushels 
230000 
25000 
8,820000 
i  ,969000 
26,265000 

13-7 

14.1 

14.1 

16.3 

18.4 

18.3 

19.1 

2,085000 

37,309000 

10.9 
10.6 
8-3 
10.3 
7.2 
6.0 
6.9 

12.5 

12.8 

8.3 
10.8 
6.6 
6.6 
6.9 

I2.I 
13-3 

8.8 
10.3 

6.2 

5-7 
6.1 

16.0 
15.0 
10.3 
10.8 
7-5 
7-7 
7-9 

16.0 
16.0 

12-5 

12.7 
9.1 
9-3 
IO.O 

20.5 

IQ.O 
12.5 
12.2 
9-5 
8-5 
0.0 

15.0 
16.4 
n.t 
13-0 

IO.O 

9.0 
9-2 

14.0 
14-5 
II.  2 
13-0 

9-5 

IO.O 
IO.O 

17.0 
17.4 

12.  i 
12.5 
11. 
II.O 
IO-S 

118000 
770000 
790000 
370000 
570000 
381000 
245000 

1,652000 
11,165000 
8,848000 
4,810000 
5,415000 
3,810000 
2,450000 

8.9 

8.9 

9.0 

10.6 

12.4 

14-3 

12.3 

n.8 

13-3 

|    3,244000 

38,150000 

I2.O 
II.O 
II.9 

13-4 
13-7 

14.6 
13-9 
13-1 
16.1 

12.2 

14.4 
I3-Q 
14-3 
14.8 
13-0 

13-8 

12.2 
13-0 
13-8 
IS-7 

20.4 
20.7 
19-5 
13-1 
16.3 

I6.3 
14-4 

1  8.0 
14-5 
14.1 

16.0 
16.6 
13.0 
1  8.0 
18.2 

iS-9 
IS-3 
17.4 
18.8 
19-5 

16.2 

15.6 
15.0 
18.0 

IQ.  2 

1,480000 
2,165000 
1,810000 
775000 
179000 

23,532000 
33,124000 
31,494000 
14,570000 
3,484000 

12.3 

13-9 

14.2 

13-3 

19.1 

15-8 

15.6 

16.6 

15-9 

6,409000 

106,204000 

15.0 

12.6 
12.8 

14.8 
15.7 
13.1 

12.8 
10.2 
II.4 

II.9 
13-9 
II.9 

13-7 

I2.Q 
12.8 
I4-S 
II.O 

10.8 

12.8 

13-3 
I4-I 
12.2 
12.2 
II.  I 
IS-4 
13-7 

10.9 
iS-7 
14.8 
13.0 
13-4 

22.0 
IS-' 

13.0 
13-4 
13-2 

IO.O 
II.  2 

18.1 

II.O 
12.2 

12.8 

17.2 

IO.O 

1  1.6 

12.8 

17.2 

12.6 

12.7 

1  6.8 
17.0 
14.7 
13-7 
14.1 
18.8 
14.4 

16.0 

21.  0 
13.8 

5-0 

12.8 

16.1 
14-0 

12.  1 

5,600000 
439000 
1  ,943000 
6,625000 
3,375000 
2,640000 
6,045000 

94,080000 
7,446000 
28,562000 
90,762000 
47,588000 
49,650000 
87,203000 

13-0 

13-0 

14.2 

15-2 

!  26,667000 

405,291000 

9.2 
7-7 
7-6 
9.2 

12.8 

10.3 

9-7 
6.6 
6.4 

6.2 

10.8 
7-i 

II.  2 

8.3 
6.9 
6.9 
10.4 
11.4 
8.6 

1  1.2 

9-5 
9.1 
9.4 
12.3 
14.1 
9-1 

I4.I 
12.5 
II.O 
IO.O 

n-5 
13-7 
10.8 

12.0 

9-5 

IO.O 
II.O 

7-4 
9.0 
9-5 

9-7 

1  1.6 

IO.O 

li-S 

14-5 

II.O 

1  1.6 

IO.O 

II.  I 

n.8 
10.4 
10.5 

II.O 

9.1 

12.8 

11.4 

12.8 

11.7 

12.  0 
14.0 
IS.O 
16.3 
13-9 

670000 
800000 
98000 

IOOO 

555000 
1,225000 
151000 

7,906000 
8,320000 
1,029000 

I  IOOO 

5,050000 
15,680000 
1,721000 

8.6 

8.2 

9-7 

ii-S 

12.8 

"•3 

14-3 

3,500000 

39,717000 

21.6 

18.9 
14.8 

17.7 
17-0 
19.1 
13-6 
13-9 
1  8.0 
18.1 
17.2 
16.3 
I7-S 
13-0 

19.8 
20.  i 
19.2 
14.7 
15-2 
17.6 
17.4 
18.4 
17.6 
16.7 
12.4 

26.9 

22.6 
23-1 
19.6 
21.6 

23.4 
25.9 

23.8 

23.0 
18.4 

"•3 

24.0 
28.7 
32.5 
25.0 
25.2 
27.4 
3i-5 
24-4 

20.8 
2O.O 
I7-I 
20.8 

28.8 
28.5 
29.0 
24.0 
25-9 
28.8 
32.0 
25-3 
26.0 
23-4 
15-0 

24.2 
25.4 

21.0 
25.0 
26.7 
26.S 
30.0 
28.2 

18.8 

20.8 

14.6 

30.8 
28.7 
29-S 
24-S 
25.0 
25-9 
28.7 
27-8 
23.2 

20.2 
I4.O 
22.9 

22.O 
25.0 
22.2 
2O.  O 
22.3 
22.4 
29.0 
22.4 
17.2 
21-5 

18.0 

2O.O 

350000 
80000 
365000 
41000 
16000 
235000 
36000 
520000 
1,540000 
810000 
825000 

10,764000 
2,297000 
10,758000 
1,004000 
400000 
6,000000 
1,033000 
14,465000 
35,780000 
16,377000 
11,550000 

Wyoming      .... 
Colorado  

New  Mexico      .    .    . 

Utah    

Nevada     
Idaho  

Washington  .... 
Oregon     
California      .... 
Western    .    .    . 
United  States    .    . 

15.4 

14-3 

13-9 

16.8 

22.6 

2O.2 

4,818000 

110,518000 

II.9 

12.3 

12.7 

I3-S 

IS-S 

14.0 

I4.O 

IS-8 

I4.I 

46,723,000 

737,180000 

APPENDIX 


613 


INTERNATIONAL    TRADE    IN    WHEAT,    INCLUDING    WHEAT    FLOUR, 

1902-1906 

EXPORTS 


COUNTRY 

YEAR 
BEGIN- 
NING 

1903 

(Bu.) 

1903 

(Bu.) 

19O4 

(Bu.) 

1905 

(Bu.) 

19O6 

(Bu.) 

Argentina  .  .  . 
Australia  .  .  . 
Austria-Hungary  . 
Belgium  .... 
British  India  .  . 

Bulgaria  .  .  . 
Canada  .... 
Chile  

Jan. 
Jan. 
Jan. 
Jan. 
Apr. 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

San. 
an. 
an. 
uly 

25,672368 
10,799165 
5,S3427o 

i3»89°599 

21,389010 

9,320644 
39,820238 
1,043883 
4,044662 
37i3498°4 

34,715888 
114,872260 
1,875580 
202,905598 
14,499026 

65,421537 
1,489763 
5,532485 

13,362799 
50,684276 

13,185710 
24,452019 
2,270728 

7,956750 
40,218462 

31,860939 
158,064833 
2,016358 
120,727613 
9,3I1[307 

90,115119 
38,850166 

3,984789 
18,217597 
83,128272 

20,286368 
21,110205 
3,146416 
8,640465 
41,268227 

26,718698 
I74,334i82 
3,098326 
44,112910 
10,955245 

112,718476 
32,506453 
3,630659 
18,496029 
37,483073 

17,508259 
48,566652 
706932 
10,512765 
53.95M47 

65,246599 
181,759796 
3,520627 
97,609007 
I3,Il6253 

89,128802 
38,878679 
4,059153 
18,030378 
32,213417 

11,037613 
42,224469 
1  706932 
10,350641 
33,626290 

'65,246599 
3l37,I3°392 
3,365644 
146,700424 
3  14,227728 

Germany  2  .  .  . 
Netherlands  .  . 

Roumania  .  .  . 
Russia  .... 
Servia  .... 
United  States  .  . 
Other  countries 

Total      .     .     . 

537,732995 

546,555579 

587,966975 

697,  333027 

646,927161 

IMPORTS 


Belgium    .... 
Brazil        .... 
Denmark       .     .     . 
Finland    .... 
France      .... 

an. 
an. 
an. 
an. 
an. 

57,507743 
10,845841 

5,865624 
3,026987 
10,509786 

59.797102 
12,129189 
5,467021 

3,442443 
18,516169 

64,160454 
i3,74535i 
5,373202 
3,4i376i 
8,625293 

64,976813 
14,983303 
4,691567 
3,580581 
7,347i85 

68,178372 
16,303441 
5,648708 
3,966877 
11,732007 

Germany  2     .     .     . 
Greece      .... 
Italy     

an. 
an. 
an. 
an. 
an. 

77,822604 
6,396218 
43,330190 
2,427147 
55.752861 

72,501263 
6,207668 
43,I74711 
9,l64759 
58,552553 

75,436433 
5,207403 
29,670497 
6,702045 
58,916277 

85,136923 
5,863742 

43>I04i99 
7,873865 
70,380247 

74,873885 
7,924950 
50,541670 
5,622967 
54,678154 

Japan       .... 
Netherlands       .     . 

Portugal        .     .     . 
Spain        .... 
Sweden     .... 
Switzerland        .     . 
United  Kingdom    . 

Other  countries 
Total      .     .     . 

an. 
an. 
an. 
an. 
an. 

336955 
2,620395 
7,953342 
15,226501 
200,577004 

43,509254 

2,748269 
3,363238 
8,658924 
16,324627 
217,100937 

58,579453 

3,282298 
8,253950 
8,446395 
17,220343 
219,713497 

47,873864 

4,672573 
35,502385 

7,515498 
16,158553 
212,089481 

49,518455 

1  4,672573 
20,040928 
8,216745 
16,196009 
208,920370 

349,598374 

543,7o8452 

595,728326 

576,041073 

633,395370 

607,116030 

1  Year  preceding. 

2  Not  including  free  ports  prior  to  March  i,  1906. 
8  Preliminary. 


614 


APPENDIX 


WHEAT  —  Continued 

QUANTITY  AND  PERCENTAGE  OF  EXPORTS  OF  DOMESTIC  WHEAT,  1907  AND  1908,  BY 

LEADING  PORTS 


CUSTOMS  DISTRICT 

YEAR  ENDING  JUNE  30  — 

1907 

1008  (Preliminary) 

Bushels 

Per  Cent  of 
Total 

Bushels 

Per  Cent 
of  Total 

New  York         

18,679225 
6,012732 
7,198844 
8,391450 
5,026578 

14,172021 
2,622505 

5,49693S 
1,940582 

7,028551 

24.4 
7.8 
9-4 

II.O 

6.6 

18.5 
3-4 
7.2 

2-5 

9.2 

21,478019 
14,699237 
13,411581 
12,357077 
8,763989 

8,112828 
5,261870 
5,020235 
3,845004 
7,262321 

21.4 
14-7 
13-4 
12.3 
8.7 

8.1 
5-3 
S-o 
3-8 
7-3 

Puget  Sound    

Willamette       

Philadelphia     

Boston  and  Charlestown    

New  Orleans    

Duluth    

All  other      

Total        

76,569423 

100.  0 

100,212161 

IOO.O 

AVERAGE  YIELD  OF  WHEAT  IN  COUNTRIES  NAMED,3  BUSHELS  PER  ACRE,  1898-1907 


YEAR 

UNITED 
STATES  * 

RUSSIA, 

EURO- 
PEAN2 

GER- 
MANY2 

AUSTRIA  2 

HUNGARY 
PROPER  2 

FRANCE  l 

UNITED 

KING- 
DOM1 

Average  (1888  to  1897) 

12.8 

8.4 

22.7 

i5.6 

17.9 

17.6 

30.1 

1898                .... 

iz.i 

o  6 

18  o 

«.8 

12.1 

8.7 

28  4 

17  8 

^n-8 

IOOO 

12.1 

8.7 

27.  Q 

i  ?.< 

16.0 

IO.2 

2Q.I; 

I  S.O 

8.1 

27    S 

16  7 

i  c  i 

18  c 

7I.O 

IOO2 

14.? 

I  I.I 

1O.1 

IO.O 

20.  7 

20.  2 

77.  Q 

IOO7 

12.  0 

17.8 

22.8 

71.  1 

1904          

12    S 

IO    C 

16  7 

27.8 

IOO1 

14..  S 

28   < 

18  7 

20  8 

73.  0 

1006 

I  ?   C 

•24.7 

IOO7 

18  o 

^•O 

Average  (1898  to  1907) 

13-9 

9-3 

28.4 

i8.3 

17.9 

20.8 

32-6 

1  Winchester  bushels.  2  Bushel  of  60  pounds. 

3  For  the  ten  years,  1886  to  1895,  the  average  yield  of  wheat  was  27.7  bushels 
per  acre  in  Holland,  and  37.3  in  Denmark;  and  for  the  succeeding  ten-year  period, 
1896  to  1905,  the  average  yield  in  Holland  was  31.2  bushels,  and  in  Denmark  40.6 
bushels  per  acre,  with  only  two  years  below  a  4o-bushel  average  (35.2  bushels  in 
1898,  and  29.2  in  1901). — C.G.H. 


APPENDIX 


OATS 

OAT  CROP  OF  COUNTRIES  NAMED,  1903-1907 


COUNTRY 

19O3 

(Bu.) 

1904 

(Bu.) 

19O5 

(Bu.) 

1906 

(Bu.) 

1907 

(Bu.) 

United  States    .     . 
Canada    .... 
Mexico     .... 
Total  North 
America     .     . 

Austria     .... 
Hungary  proper     . 
France     .... 
Germany      .     .     . 
Russia  (European) 
Great  Britain  — 
England    .     .     . 
Scotland    .     .     . 
Wales  .... 
Ireland     .... 
Total  United 
Kingdom   .     . 

Total  Europe     . 

Russia  (Asiatic) 
Total  Asia     .     . 
Total  Africa  .     . 

Australia.     .     .     . 
New  Zealand     .     . 
Total  Australasia 
Grand  total   .     • 

784,094000 
211,192000 
13000 

894,596000 
208,024000 
18000 

953,216000 
234,099000 
17000 

964,905000 
251,194000 
17000 

754,44300° 
210,869000 
17000 

995,299000 

1,102,638000 

1,187,332000 

i,  216,  1  16000 

965,329000 

128,330000 
87,334000 
300,366000 
542,432000 
728,049000 

85,400000 
36,379000 
6,832000 
58,816000 

109,611000 
62,775000 
257,811000 
477,852000 
1,065,068000 

86,728000 
37,034000 
7,661000 
60,142000 

123,880000 
78,009000 
269,581000 
451,017000 
851,667000 

76,453000 
36,390000 
7,264000 
60,754000 

154,551000 

87,733°°° 
256,943000 
580,875000 
633,291000 

84,102000 
35,108000 
8,063000 
62,751000 

170,657000 
79,484000 
314,132000 
630,324000 
820,621000 

94,707000 
36,056000 
7,875000 
60,080000 

187,427000 

191,565000 

180,861000 

190,024000 

198,718000 

2,268,425000 

2,402,641000 

2,203,967000 

2,222,575000 

2,493,53200° 

71,734000 

59,135000 

84,995000 

79,713000 

85,176000 

72,215000 
12,116000 

7,527000 
22,452000 

59,552000 
14,309000 

85,397000 
12,077000 

80,072000 
12,418000 

85,576000 
12,008000 

18,094000 
15,583000 

9,064000 
15,012000 

10,805000 
13,108000 

14,041000 

I  I,  5550°0 

29,979000 

33,677000 

24,076000 

23.9I3°°o 

25,596000 

3.378,034000 

3,612,817000 

3,5i2,849'ooo 

3,S55,°94°°o 

3,582,O4IOOO 

AVERAGE  YIELD  OF  OATS  IN  COUNTRIES  NAMED,  1898-1907 
Bushels  per  Acre 


YEAR 

UNITED 
STATES  1 

RUSSIA, 

'EURO- 
PEAN2 

GER- 
MANY* 

AUSTRIA  * 

HUNGARY 
PROPER  J 

FRANCE  J 

UNITED 

KING- 
DOM1 

Average  (1888  to  1897) 

25-7 

16.8 

36-9 

23-9 

25-3 

29.2 

43-i 

1898  

28.4 

16.2 

47.1 

27.4 

30.2 

29.0 

46.1 

1800  . 

10.  2 

27.1 

48.0 

30.2 

73.1 

27.8 

44.2 

IOOO    . 

S      f. 

20.  6 

20.  o 

48.0 

25.2 

28.1 

25.7 

43-5 

IOOI    . 

25.8 

14.4 

44.6 

25.6 

28.1 

23.5 

42.9 

IOO2    . 

?4.c 

21.8 

SO.  I 

27.7 

34.O 

29.2 

48.3 

1007  . 

28.4 

17.7 

51-2 

28.3 

34.5 

31.6 

44.2 

32.1 

2=;.  7 

46.2 

24.3 

25.6 

27.2 

44.2 

TOO?    • 

74.O 

20.  2 

43.6 

27.7 

3I.I 

28.6 

43-9 

IOO6    . 

31.2 

IS-1 

55-7 

34.1 

34.3 

27.0 

46.1 

I9«>7    

23-7 

19.7 

58.2 

35-7 

29.7 

31-8 

45-i 

Average  (1898  to  1907) 

29.8 

19.4 

49-3 

28.6 

3°-9 

28.1 

44-7 

Winchester  bushels. 


2  Bushels  of  32  pounds. 


6i6 


APPENDIX 


BARLEY 
BARLEY  CROP  OF  COUNTRIES  NAMED,  1903-1907 


COUNTRY 

1903 

(Bu.) 

1904 

(Bu.) 

1905 

(Bu.) 

1906 

(Bu.) 

1907 

(Bu.) 

United  States    .     . 
Canada    .... 
Mexico     .... 
Total   North 

131,861000 
39,035000 
9,061000 

139,749000 
42,244000 
7,355°°° 

136,651000 
45,389000 
7,000000 

178,916000 
50,820000 
7,000000 

153,597°°° 
45,235°°° 
7,000000 

America     .     . 

1  79,95  7°o° 

189,348000 

189,040000 

236,736000 

205,832000 

Austria     .... 
Hungary  proper     . 
France     .... 
Germany       .     .     . 
Russia  (European) 
Great  Britain  — 
England    .     . 
Scotland    .     .     . 
Wales  .... 
Ireland    .... 

73,873000 
64,577000 

43,345°°° 
152,653000 
350,486000 

50,628000 
7,739000 
2,981000 
6,076000 

66,815000 
49,915000 
38,338000 
135,409000 
339,717000 

48,511000 
7,408000 
3,077000 
5,478000 

70,469000 
62,453000 
40,841000 
134,204000 
338,836000 

48,778000 
8,257000 
2,906000 
7,181000 

76,024000 
69,747000 
36,538000 
142,901000 
304,276000 

5I,543°°° 
7,803000 
3,116000 
7,21  1000 

78,548000 
63,078000 
45,095000 
160,650000 
344,104000 

51,912000 
7,466000 
2,885000 
6,995000 

Total  United 
Kingdom    .     . 

67,424000 

64,474000 

67,122000 

69,673000 

69,258000 

Total  Europe     . 

931,758000 

841,070000 

867,392000 

907,895000 

911,451000 

Cyprus     .... 
Japan  

3,969000 

3,122000 

2,980000 

2,778000 

3,000000 
90  544000 

Russia  (Asiatic)     . 

6,984000 

6.538000 

8,130000 

7,763000 

9,345000 

Total  Asia     .     . 

70,728000 

90,1512000 

88,596000 

94,558000 

102,039000 

Africa       .     ..    .     . 

50,987000 

52,097000 

35,7°3°°° 

44,102000 

44,205000 

Australia  .... 
New  Zealand     .     . 

1,184000 
1,172000 

2,740000 
1,197000 

2,084000 
1,164000 

1,945000 
1,056000 

2,319000 
1,068000 

Total  Australasia 

2,356000 

3,937000 

3,248000 

3,001000 

3,387°°° 

Grand  total    .     . 

1,235,786000 

1,176,964000 

1,183,979000 

1,286,292000 

1,267,814000 

AVERAGE  YIELD  OF  BARLEY  IN  COUNTRIES  NAMED,  BUSHELS  PER  ACRE,  1898-1907 


YEAR 

UNITED 
STATES  ' 

RUSSIA, 
EURO- 
PEAN* 

GER- 
MANY* 

AUSTRIA  * 

HUNGARY 
PROPER  2 

FRANCE  l 

UNITED 

KING- 
DOM l 

Average  (1888  to  1897) 

23.2 

12.6 

27.6 

20.  2 

20.3 

21-5 

34-4 

1898       

22.  0 

37.4. 

1800 

2C.C 

33  8 

24.9 

24.0 

22.7 

TS-8 

1900       

I  I     C 

20.  2 

21.8 

•32.7 

IOOI 

2S.6 

1  1.2 

77.2 

22-4 

20.  o 

21.  1 

72.7 

1902       

jc  6 

24.6 

24  7 

24.   ? 

77.  0 

loot 

I  ?   C 

76   7 

24.8 

2?    I 

2?.  2 

77.4 

IQO4 

27.2 

77.7 

22.8 

10.8 

22.  0 

72.7 

IOOS 

26.8 

24   C 

7S.O 

1006       

28.7 

14.1 

7<1.2 

26.1 

26.8 

20.8 

76.2 

1907     •    

23.8 

14.2 

38.2 

27-3 

20-7 

24.4 

36.8 

Average  (1898  to  1907) 

25-5 

'3-7 

34-4 

23-9 

23.8 

22-9 

34-9 

1  Winchester  bushels. 


2  Bushels  of  48  pounds. 


APPENDIX 


617 


RYE 
RYE  CROP  OF  COUNTRIES  NAMED,  1903-1907 


COUNTRY 

1903 

(Bu.) 

1904 

(Bu.) 

1905 

(Bu.) 

1906 

(Bu.) 

1907 

(Bu.) 

United  States      .     . 
Canada      .... 
Mexico       .... 
Total  No.  America 

Austria-Hungary     . 
France       .... 
Germany  .... 
Russia  (European) 
United  Kingdom     . 
Total  Europe  . 

Russia  (Asiatic) 
Total  Asia       .     . 

Australia   .... 
New  Zealand      .     . 
Total  Australasia 
Grand  total     .     . 

29.363000 
3,915000 
136000 

27,242000 
2,995000 
67000 

28,486000 
2,748000 
70000 

33,375000 
2,273000 
70000 

31,566000 
2,002000 
70000 

33,414000 

30,304000 

31,304000 

35,718000 

33,638000 

132,267000 
57,951000 
389,923000 
879,883000 

2,000000 

I37»963000 
52,141000 
396,075000 
977,981000 
2,000000 

151,641000 
58,116000 
378,204000 
708,692000 
2,000000 

!53,  515000 
50,429000 
378,948000 
638,675000 
2,000000 

129,234000 
58,578000 
384,150000 
776,000000 
2,000000 

1,594,370000 

1,681,280000 

1,436,406000 

1,371,881000 

1,479,851000 

32,059000 

30,457000 

28,750000 

28,169000 

32,000000 

32,059000 

3°i457000 

28,750000 

28,169000 

32,000000 

78000 
40000 

131000 

2IOOO 

85000 
33°°° 

94000 
•  65000 

89000 
43000 

1  1  8000 

152000 

i  i  8000 

159000 

132000 

1,659,961000 

1,742,193000 

1,496,578000 

I,435,927o°0 

1,545,621000 

AVERAGE  YIELD  OF  RYE  IN  COUNTRIES  NAMED,  1898-1907 
(Bushels  per  Acre) 


YEAR 

UNITED 
STATES 

RUSSIA, 
EURO- 
PEAN 

GER- 
MANY 

AUS- 
TRIA 

HUN- 
GARY 
PROPER 

FRANCE 

IRE- 
LAND 

Average  (1888  to  1897)  . 

13-5 

IO.O 

19.0 

J5-5 

16.3 

17.1 

25-4 

1808 

M.6 

10.6 

17  7 

18  ? 

2S  S 

1800 

12.8 

21  < 

18  7 

18  2 

2S  8 

IOOO 

IS.  I 

12.7 

i  c.i 

2S.7 

IOOI 

IS.  3 

IO.3 

n  8 

16  7 

27.3 

IOO2 

17  O 

12.  S 

18  2 

28.1 

IQO7 

IS.  A. 

18  2 

18  2 

18  i 

IQO4. 

I  S  2 

16  6 

1905   

I6.S 

IO.I 

i8.<; 

27.O 

1906   

16  7 

8.8 

2S  I 

19  8 

16  7 

27  6 

1907  

16.4 

10.8 

25-7 

18.8 

16.2 

18.2 

27.0 

Average  (1898  to  1907)  . 

15-8 

"•5 

24.6 

18.1 

J7-5 

17.2 

26.7 

NOTE.  The  student  may  well  remember  that  the  reported  crop  yields, 
acreage,  and  production  are  based  upon  estimates,  while  the  statistics  for  im- 
ports and  exports  are  based  upon  definite  data.  In  census  years  the  estimates 
are  made  with  greater  care  and  detail,  but  even  these  are  largely  estimates. 

In  some  cases  the  annual  estimates  are  undoubtedly  far  from  the  facts,  as  is 
strongly  suggested  by  comparing  the  federal  "statistics"  with  the  "statistics" 


6i8 


APPENDIX 


POTATOES 
POTATO  CROP  OF  COUNTRIES  NAMED,  1902-1906 


COUNTRY 

1902 

(Bu.) 

1903 

(Bu.) 

1904 

(Bu.) 

1905 

(Bu.) 

1906 

(Bu.) 

United  States  . 
Canada  .... 
Mexico    .... 
Newfoundland 
Total  North 
America    . 

Chile  

284,633000 
51,206000 
347000 
1350000 

247,128000 
56,944000 
539000 
i,350000 

332,830000 

55,436oo° 
527000 
1,350000 

260,741000 
55,257000 
400000 
1,350000 

308,038000 
59,804000 
400000 
1,350000 

337,536oo° 

305,961000 

390,143000 

317,748000 

369,592000 

11,616000 

584,619000 
441,055000 
1,596,969000 
1,028,036000 

10,349000 

544,166000 
426,422000 
1,576,361000 
887,600000 

6,131000 

520,461000 
451,039000 

I,333.326oo° 
893,908000 

6,532000 

765,117000 
523,876000 
1,775,579000 
1,032,888000 

6,532000 

709,237000 
372,076000 

1,577,  653°°° 
939,717000 

Austria-Hungary  . 
France    .... 
Germany     .     . 
Russia  (European) 

United  Kingdom  : 
Great  Britain    . 
Ireland    .     . 
Total  United 
Kingdom 

Total  Europe   . 

Japan     .... 
Russia  (Asiatic)   . 
Total  Asia    .     . 

Total  Africa     . 

Australia     .     .     . 
New  Zealand  . 
Total  Australasia 
Grand  total  . 

119,250000 
•  101,761000 

108,779000 
88,227000 

133,961000 
98,635000 

140,474000 
127,793000 

128,005000 
99,328000 

221,011000 

197,006000 

232,596000 

268,267000 

227,  333°°° 

4,280,644000 

4,038,566000 

3,843,081000 

4,779,59°000 

4,3°5>3I3000 

7,418000 
13,142000 

9,824000 
19,364000 

11,274000 
18,800000 

16,255000 
18,865000 

16,255000 
16,481000 

20,560000 

29,188000 

30,074000 

35,120000 

32,736000 

3,884000 

3,541000 

4,048000 

4,071000 

4,138000 

12,039000 
7,721000 

14,973000 
7,215000 

16,777000 
7,795000 

11,071000 
5,025000 

10,016000 
4,607000 

19,760000 

22,188000 

24,572000 

16,096000 

14,623000 

4,674,000000 

4,409,793000 

4,298,049000 

5,  J  59^5  7ooo 

4,732,934ooo 

from  some  of  the  states  which  have  crop-reporting  boards,  such  as  the  Illinois 
State  Board  of  Agriculture  and  the  Iowa  Weather  and  Crop  Service.  Thus  in 
1907,  Illinois  produced,  according  to  the  federal  report,  more  than  40  million 
bushels  of  wheat,  but  less  than  25  million  bushels  by  the  state  report.  In  1908 
the  federal  estimate  gave  Illinois  9,450,000  acres  of  corn,  while  the  state  report 
was  6,780,000  acres.  The  same  year  the  state  of  Iowa  claimed  to  produce 
only  4,968,250  bushels  of  wheat,  but  in  the  federal  report  Iowa  receives  credit 
for  8,068,000  bushels.  These  are  extreme  variations,  but  they  should  serve 
to  emphasize  the  fact  that  crop  "statistics"  should  not  weigh  heavily  as 
against  actual  data,  such,  for  example,  as  the  records  of  the  long-continued 
field  experiments  of  Rothamsted,  Pennsylvania,  etc. 

On  the  other  hand,  the  United  States  crop  statistics  are  probably  as  good  as 
those  from  any  nation ;  and,  while  gross  errors  may  appear  in  specific  instances, 


APPENDIX 


619 


RICE 
RICE  CROP  OF  COUNTRIES  NAMED,  1902-1906 

[Mostly  cleaned  rice.  China,  which  is  omitted,  has  a  roughly  estimated  crop  of  50,000,000,000  to 
60,000,000,000  pounds.  Other  omitted  countries  are  Afghanistan,  Algeria,  Brazil,  Colombia, 
Federated  Malay  States,  Madagascar,  Persia,  Russia  (Asiatic),  Trinidad  and  Tobago,  Turkey 
(Asiatic  and  European),  Venezuela,  and  a  few  other  countries  of  small  production.] 


COUNTRY 

1903 

(Lb.) 

1903 

(Lb.) 

1904 

(Lb.) 

19O5 

(Lb.) 

1906 

(Lb.) 

United  States: 
Contiguous       .     . 
Hawaii    .... 

319,400000 
33,400000 
40,000000 

560,800000 
33,400000 
48,700000 

586,000000 
33,400000 
62,000000 

378,000000 
33,400000 
62,000000 

496,000000 
33,400000 
62,000000 

Total  No.  America 

401,600000 

652,000000 

690,800000 

482,800000 

600,800000 

Total  South  America 

85,600000 

87,500000 

95,100000 

97,300006 

120,500000 

Italy  

359.800000 

417,100000 

394,600000 

478,800000 

475,400000 

Total  Europe    .     . 

1,038,300000 

1,188,500000 

1,167,500000 

1,166,500000 

1,215,000000 

British  India: 
British  Provinces 
Native  States    . 
Japanese  Empire 
Total  Asia    .     . 
Total  Africa     . 

72,688,000000 
799,000000 
13.295,300000 
105,075,200000 

22,200000 

68,580,000000 
838,000000 
16,809,200000 
104,887,800000 

22,200000 

71,561,000000 
764,000000 
18,658,700000 
110,212,200000 
22,200000 

67,916,000000 
640,000000 
14,639,200000 
102,147,900000 
21,800000 

67  ,464,000000 
640,000000 
17,185,900000 
104,974,000000 
21,800000 

Grand  total      .    . 

106,626,400000 

IO6,84I,OOOOOO 

112,190,800000 

103,919,100000 

106,943,900000 

they  doubtless  approximate  the  truth  as  a  general  rule,  and  are  more  trust- 
worthy, especially  for  purposes  of  comparison,  than  some  state  estimates. 

It  should  be  kept  in  mind  that  certain  crops,  such  as  wheat,  are  now  quite 
regularly  fertilized  in  some  of  the  Eastern  and  East  Central  states. 

Comparison  of  crop  yields  in  different  states  is  most  significant  when  the 
acreage  is  also  comparable.  In  1907  the  average  yield  of  wheat  per  acre  was 
23  bushels  in  Vermont  and  only  n  bushels  in  Kansas;  but  Vermont  raised  one 
thousand  acres  and  Kansas  raised  six  million  acres,  and  on  many  thousand 
acres  the  Kansas  yield  may  have  exceeded  30  bushels  per  acre.  In  1905  the 
average  yield  of  corn  per  acre  was  42.7  bushels  in  Connecticut  and  only  39.8 
bushels  in  Illinois;  but  Connecticut  raised  only  55,595  acres  of  corn,  while 
Champaign  County,  Illinois,  raised  some  200,000  acres  of  corn,  which  made  an 
average  yield  of  65  bushels  per  acre. 

South  Carolina  is  authentically  credited  with  having  produced  239  bushels 
of  air-dry  corn  on  one  acre  of  land  in  one  season,  but  the  average  yield  for  the 
state  for  the  44  years,  1866  to  1909,  is  10  bushels  per  acre.  Even  the  average 
yield  of  corn  for  the  United  States  has  varied  from  30.8  bushels  per  acre,  in 
1872,  to  16.7  bushels,  in  1901 ;  and  if  these  records  were  interchanged  the  average 
yield  would  become  the  same  for  two  successive  2o-year  periods,  25.0  bushels 
per  acre. 


62O 


APPENDIX 


SUGAR 

SUGAR  PRODUCTION  OF  COUNTRIES  NAMED,  1903-1904  TO  1907-1908 

[European  beet  sugar,  as  estimated  by  Licht;  United  States  beet  sugar,  from  reports  of 
Department  of  Agriculture  on  the  Progress  of  the  Beet-sugar  Industry  in  the  United 
States;  production  of  British  India  (except  1907-1908)  and  of  Formosa  and  Natal  prior 
to  1905-1906  from  official  statistics;  other  data,  from  Willett  &  Gray.  The  estimates  of 
Willett  &  Gray  do  not  include  the  production  of  China,  and  some  other  less  important 
sugar-producing  countries.] 


COUNTRY 

1903-4 

(Tons1) 

1904-5 

(Tons1) 

1905-6 

(Tons1) 

1906-7 

(Tons1) 

1907-8 

(Tons1) 

CANE  SUGAR 

United  States: 
Contiguous  — 
Louisiana     

228477 

771:000 

37OOOO 

230000 

775OOO 

Texas       

19800 

Noncontiguous  — 
Hawaii     

328107 

780^76 

Porto  Rico    

130000 

145000 

2I30OO 

2IOOOO 

217000 

Total  United  States  (except 
Philippine  Islands)  .     .     . 

706380 

87SS76 

938225 

845871 

984000 

Mexico  

IO7S47 

Cuba      

1,040228 

i  163258 

I       17874.0 

115 

Total  North  America  .    .     . 

2,143911 

2,410477 

2,545l82 

2,680175 

2,609000 

Total  South  America  .    .     . 

601134 

590382 

700001 

610151 

586000 

Total  Asia     

2,876671 

3,333672 

2,926209 

3,455446 

3,481477 

Total  Africa       

355747 

25134° 

317967 

349000 

270000 

Total  Oceania    

163328 

216213 

230000 

249000 

276000 

Total  cane-sugar  production 

6,168791 

6,820676 

6,735°8i 

7,360172 

7,233477 

BEET  SUGAR 
United  States       

Canada  

Total  North  America      .     .     . 

221535 

2242O7 

290812 

443  I  63 

421897 

Austria-Hungary      

&8n?7? 

60000 

72877O 

France        

Netherlands    

Russia  

Other  countries   

Total  Europe     .     .     . 

e  88l777 

*7o&*7nn 

z:                fi 

4»  f\jo  j\j\j 

Total  beet-sugar  production 

6,102868 

4,932907 

7,22446l 

7,160163 

6,006807 

Total  cane  and  beet  sugar 

12,271659 

".  753583 

'3,959542 

I4,52°335 

I4,23°374 

1  Tons  of  2240  pounds,  except  beet  sugar  in  Europe,  which  is  shown  in  metric 
tons  of  2204.622  pounds. 


APPENDIX 


621 


SUGAR  —  Continued 
PRODUCTION  OF  SUGAR  IN  THE  UNITED  STATES  AND  ITS  POSSESSIONS,  1874-75  TO  1907-8 


CANE  SUGAR 

YEAR 

SUGAR 
(Long 
Tons) 

Louisiana 
(Long 
Tons) 

Other 
Southern 
States 
(Long 
Tons) 

Porto 
Rico 
(Long 
Tons) 

Hawaii, 
(Long 
Tons) 

Philippine 
Islands 
(Long 
Tons) 

TOTAL 
(Long 
Tons) 

1874-1875.  .  . 

I 

160047 

3454 

72128 

11197 

126089 

273015 

1875-1876.  .  . 

TOO' 

72954 

4046 

70016 

11639 

128485 

287240 

1876-1877  .  .  . 

f    IOO 

85122 

3879 

62340 

11418 

121052 

283911 

1877-1878  .  .  . 

J 

65671 

5330 

84347 

I7I57 

120096 

292701 

1878-1879  .  .  . 

2OO 

106908 

5090 

76411 

21884 

129777 

340270 

1879-1880  .  .  . 

I2OO 

88822 

3980 

57057 

28386 

178329 

357774 

1880-1881  .  .  . 

500 

121867 

61715 

41870 

205508 

436960 

1881-1882  .  .  . 

1        , 

/  71373 

5000 

80066 

50972 

148047 

355958 

1882-1883  .  .  . 

J    5°° 

I  i35297 

7000 

77632 

51705 

193726 

465860 

1883-1884.  .  . 

535 

128443 

6800 

98665 

63948 

120199 

418590 

1884-1885  .  .  . 

953 

94376 

6500 

70000 

76496 

200997 

449322 

1885-1886  .  .  . 

600 

127958 

7200 

64000 

96500 

182019 

478277 

1886-1887  •  •  • 

800 

80859 

4535 

86000 

95000 

169040 

436234 

1887-1888  .  .  . 

255 

I5797I 

9843 

60000 

IOOOOO 

158445 

486514 

1888-1889  .  .  . 

1861 

144878 

9031 

62000 

I20OOO 

224861 

562631 

1889-1890.  .  . 

2203 

124772 

8x59 

55000 

I2OOOO 

M2554 

452688 

1890-1891  .  .  . 

3459 

215844 

6107 

50000 

125000 

136035 

536445 

1891-1892  .  .  . 

5356 

160937 

4500 

70000 

"5598 

248806 

605197 

1892-1893  .  .  . 

12018 

217525 

5000 

50000 

I4OOOO 

257392 

681935 

1893-1894.  .  . 

19950 

265836 

6854 

60000 

136689 

207319 

696648 

1894-1895  .  .  . 

20092 

3X7334 

8288 

525OO 

131698 

336076 

865988 

1895-1896  . 

29220 

237721 

4973 

50000 

201632 

230000 

753546 

1896-1897  .  .  . 

37536 

282009 

5570 

58000 

2242l8 

2O2OOO 

809333 

1897-1898  .  .  . 

40398 

3I0447 

5737 

54000 

204833 

I78OOO 

793415 

1898-1899  .  .  . 

32471 

245512 

3442 

53826 

252507 

93000 

680758 

1899-1900  .  .  . 

72944 

147164 

2027 

35000 

258521 

62785 

578441 

1900-1901  . 

76859 

270338 

2891 

80000 

321461 

55400 

806949 

1901-1902  . 

164827 

321676 

3614 

85000 

3I75°9 

78637 

971263 

1902-1903  .  .  . 

194782 

329226 

3722 

85000 

391062 

9OOOO 

,093792 

1903-1904  .  .  . 

214825 

228477 

2  19800 

130000 

328103 

84000 

,005205 

1904-1905  .  .  . 

216173 

335000 

2  15000 

145000 

380576 

106875 

,198624 

1905-1906  .  .  . 

279393 

330000 

I2OOO 

213000 

383225 

M5525 

,363I43 

1906-1907  . 

431796 

230000 

2  I3OOO 

210000 

392871 

I450OO 

,423167 

1907-1908  .  .  . 

413954 

335000 

2  I2OOO 

217000 

420000 

135000 

,532954 

1  Production  uncertain ;  not  exceeding  quantity  stated. 

2  Texas. 


622 


APPENDIX 


INTERNATIONAL  TRADE  IN  SUGAR,   1902-1906 
EXPORTS 


COUNTRY 

YEAR 
BEGIN- 
NING 

1902 

(Lb.) 

1903 

(Lb.) 

1904 

(Lb.) 

1905 

(Lb.) 

1906 

(Lb.) 

Austria-Hungary  . 
Argentina    .    .    . 
Belgium  .... 
Brazil      .... 
British  Guiana     . 

British  India    .     . 
China      .... 
Cuba  
Dutch  East  Indies 
Egypt     .... 

Formosa      .     .     . 
France    .... 
Germany     .     .     . 
Mauritius    .     .     . 
Netherlands     .     . 

Peru  

Jan. 
Jan. 
Jan. 
Jan. 
Apr. 

Apr. 
Jan. 
Jan. 
Jan. 
Jan. 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

Jan. 

1,500,882186 
91,919510 
296,287771 
301,498062 
280,284480 

55,645520 
89,945867 
1,781,561643 
1,904,371591 
98,521149 

100,873254 
804,993320 
2,367,596256 
331,172713 
310,694069 

258,738790 

1,564,437691 
66,888231 
257,180695 
48,256967 
282,125760 

57.474502 
39,890000 
2,118,279646 
1,907,867045 
86,469803 

54,128545 
469,129814 
2,249,141034 
375,505049 
287,238939 

281,482880 

1,125,102823 
40,368833 
406,944665 
17,331526 
239,043840 

57,211504 
48,787467 
2,459,166945 
2,318,243282 
50,620531 

79,518816 
636,360461 
1,720,574091 
435,923559 
403,476558 

290,916853 

1,265,791878 
4,847964 
304,193682 
83,216786 
261,072000 

64,546944 
69,228800 
2,412,915391 
2,314,655085 
67,821106 

93,930689 
658,062149 
1,636,803746 
361,987596 
215,001603 

295,935805 

1,631,529629 
233690 
462,976753 
187,278992 
257,490912 

58.660896 
23,106000 
2,643,700975 
2,197,208868 
10,495854 

93,930689 
617,793487 
2,671,881051 
410,917817 
356,157015 

295,935805 

Philippine  Islands 

Jan. 
Jan 

217,486869 

188,114307 
iO7,862s84 

191,917567 

239,196273 
41,433135 

285,394747 
41,433135 

Russia     .... 
Trinidad  and 
Tobago    .    .     . 

Other  countries    . 

Jan. 
Apr.   i 

288,610934 
105,861392 
617,792000 

540,418988 
90,460944 
609,680000 

398,854898 
106,573936 
569,646000 

220,925074 
81,179056 
901,932101 

206,854118 
100,809856 
952,547723 

00 

IMPORTS 


Australia     .     .     . 

Jan. 

208,551056 

205,026640 

85^98624 

55,923056 

94,:  3  7680 

British  India    .     . 

Apr. 

549,868704 

672,147168 

724,262224 

862,453200 

1,090,152784 

Canada  .... 

July 

388,370832 

390,544660 

346,752590 

448,962523 

423,6896:4 

Cape  of  Good  Hope 

Jan. 

120,365406 

104,629048 

:o:,  46894: 

82,805094 

87,165626 

Chile      .... 

Jan. 

97,002936 

115,467959 

I24,:396:9 

75,6:0563 

75,6:0563 

China     .... 

Jan. 

607,880000 

435,7:1467 

509,959200 

626,433333 

896,422400 

Denmark     .    .    . 

Jan. 

42,051621 

77,3745i6 

82,865:27 

76,080072 

45,254827 

Egypt     .... 

Jan. 

22,84444: 

16,920099 

45,843510 

86,880895 

76,32:099 

1'in  land  .... 

Jan. 

6i,752745 

72,691465 

7:,  26353: 

73,772007 

83,322752 

France    .... 

Jan. 

220,187363 

288,073883 

179,849557 

179,460755 

222,562321 

Italy  . 

Jan. 

aa 

Q 

i*  
Japan     .... 

Jan. 

47,355501 
351,750533 

*4»477532 
523,:3:o67 

4,920073 
547,300400 

1  1,25:729 
289,129733 

3  «,°323  *  7 
104,8:6933 

Netherlands     .     . 

Jan. 

248,799655 

203,06:092 

208,329129 

167,742700 

1:8,406076 

New  Zealand  .     . 

Jan. 

84,878074 

88,197686 

9^84:944 

89,439230 

93,329376 

Norway  .... 

Jan. 

82,791956 

83,524155 

76,703054 

77,993596 

80,364:38 

Persia     .... 

Mar.  2 

167,114080 

179,4:2238 

154,8:592: 

154,2:74:5 

154,2174:5 

Portugal      .    .    . 

Jan. 

63,630016 

68,7656:0 

72,490231 

70,0::  389 

70,0::  389 

Singapore    .    .     . 

Jan. 

93.271733 

:o2,  369867 

114,407600 

1:7,958267 

::  7,958267 

Switzerland      .     . 

Jan. 

180,272161 

192,0:5742 

:75,444?o: 

i  o:',o  i  i  <m-i 

187,653456 

Turkey  .... 

Jan. 

273,612826 

273,6:2826 

273,612826 

273,6:2826 

273,6:2826 

United  Kingdom  . 

Jan. 

3,440,232768 

3,099,985504 

3,409,50:648 

3.099,597648 

3,420,6:6976 

United  States  .     . 
Uruguay      .     .     . 

July 

July 

4,216,108106 
43,235210 

3,700,6236:3 
39,934265 

3,680,932998 
49,8:43:8 

3,979,331430 
33,838445 

4,391,839975 
33,838445 

Other  countries    . 

312,6:7000 

36:^62533 

383,86:800 

587,:2259i 

552,306790 

Total  .... 

11,924,544723 

::,  309,  260635 

::,  515,  588366 

i  :,  7:  1,64049: 

:  2,725,444045 

APPENDIX 


623 


BUTTER 

INTERNATIONAL  TRADE  IN  BUTTER,  1902-1906 
EXPORTS 


COUNTRY 

YEAR 
BEGIN- 
NING 

1903 

(Lb.) 

1903 

(Lb.) 

1904 

(Lb.) 

1905 

(Lb.) 

1906 

(Lb.) 

Argentina  .  .  . 
Australia  .  .  . 
Austria-Hungary  . 
Belgium  .... 
Canada  .... 

Denmark  .  .  . 
Finland  .... 
France  .... 
Germany  .  .  . 
Italy  . 

Jan. 
Jan. 
Jan. 
Jan. 
July 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

July  i 

9,094269 

7,77797i 
15,589764 
5,643178 
34,128944 

153,808614 
21,315888 

53,879727 
4,849727 
13,420636 

5°,4i3634 
28,447776 
3,01557° 
83,463073 
44,213494 

8,896166 
2,911000 

1,175094 
30,901910 
13,728181 
4,492080 
24,568001 

176,664571 
22,700563 
59,714579 
2,796343 
14,176381 

SI.SSQ^S 
31,931872 
2,717219 
90,863488 
44,248776 

10,717824 
2,982000 

11,672157 
64,788542 

II.233431 
4,340012 

31,  764303 

179,745595 
26,891790 
49,842670 
1,766564 
I2,375425 

52,053041 
35,208320 
3,367075 
87,705713 
43,144662 

10,071487 
2,457000 

11,890040 
55,904151 

8.944I51 
3,800594 
34,031525 

176,081731 
35,i3590i 
49,781584 
1,834907 
I3,359789 

51,162980 
34,240864 
3,612714 
86,966484 
40,636298 

27,36o537 
3,952034 

9,712076 
75,765536 
7,740648 
3,704232 
18,243740 

175,043639 
33,192114 

39,307325 
95I5I5 
10,746430 

56,404861 
35,865200 
3,281403 
114,369238 
35,712817 

12,544777 
3,726146 

Netherlands  .  . 
New  Zealand  .  . 
Norway  .... 
Russia  .... 
Sweden  .... 

United  States  .  . 
Other  countries 

Total     .     .     . 



540,869431 

596,613867 

628,427787 

638,696284 

636,311697 

IMPORTS 


COUNTRY 

YEAR 
BEGIN- 
NING 

1902 

(Lb.) 

1903 

(Lb.) 

1904 

(Lb.) 

19O5 

(Lb.) 

1906 

(Lb.) 

Australia       ... 
Belgium   .... 
Brazil       .... 
Cape  of  Good  Hope 
Denmark       .     .     . 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

6,901779 
7,375362 
6,270893 
6,341566 
I5,432354 

1,887148 
9,788817 
5,496134 
6,055075 
12,786808 

43873 
9,7277!4 
5,64-2179 
5,294516 
13,007270 

592201 
10,054979 
6,567718 
5,25i72i 
12,566345 

70143 
11,128520 
5,344412 
4,681766 
13,049158 

Dutch  East  Indies 
Egypt       .... 
France      .... 
Germany       .     .     . 
Natal       .... 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

2,788108 
2,199657 
12,042518 
36,794039 
1,662002 

2,945909 
2,366386 
10,260344 
53,558205 

2,121121 

3,021377 
3,126945 
10,067424 
75,705838 
3,17i875 

2,957073 
3,066949 
10,066650 
79,524904 
2,142003 

3,049962 
2,958784 
11,402808 
80,896179 
2,142003 

Netherlands       .     . 
Russia      .... 
Sweden     .... 
Switzerland  .     .     . 
Transvaal     .     .     . 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

1,5*4533 
856054 
1,148959 
9,705187 
3,269411 

2,665917 
838214 
919839 
10,970199 
5,119642 

5,858391 
1,158390 

1,305925 
10,889289 
4,514468 

5,439836 
1,103318 
911993 
11,955445 
4,73!433 

5,630865 
577805 
1,316117 
7,882660 
4,73J433 

United  Kingdom    . 
Other       .... 

Total     .... 

Jan.  i 

440,221264 
13,984000 

447,684496 
14,563000 

465,285968 
12,295000 

456,662976 
17,009360 

477,092448 
18,968003 

568,507686 

590,027254 

630,116442 

630,604904 

650,863066 

624 


APPENDIX 


COTTON 
COTTON  CROP  OF  COUNTRIES  NAMED,  1902-1906 

[No  statistics  for  Siam  and  some  other  less  important  cotton-growing  countries.     Bales 
of  500  pounds,  gross  weight,  or  478  pounds  of  lint,  net] 


COUNTRY 

1902 

(Bales) 

1903 

(Bales) 

1904 

(Bales) 

19O5 

(Bales) 

1906 

(Bales) 

United  States      

10.63004? 

9,851129 

13,438012 

10,575017 

13,273809 

Mexico      

103910 

i68oq8 

25327I 

253271 

253271 

Total  North  America   .... 

10,740345 

10,028813 

13.701054 

10,840532 

I3,539663 

Argentina       

17 

26 

142 

495 

IOOOO 

Brazil    

285000 

22OOOO 

270000 

361:000 

Peru      

38200 

43776 

45672 

49190 

58283 

Total  South  America    .... 

3493°5 

335^4 

271674 

326269 

439866 

Greece       

82OO 

8200 

Italy      

2  7OO 

27OO 

2  7OO 

27OO 

Turkey      

8OOO 

7OOO 

6000 

7OOO 

7OOO 

Total  Europe      

2O5Q6 

19650 

18710 

1970S 

I97I3 

British  India,  including  native  states 
China    
Dutch  East  Indies  

3,138910 
I,2OOOOO 
8267 

2,995875 
1,200000 

3,O28000 
I,2OOOOO 

I  5  76? 

3,32OOOO 
I,2OOOOO 

3,505000 
I,2000OO 

Taoan  . 

16262 

jo.po.ii 

Korea  

^OOOO 

Persia  

56282 

71  ZOO 

8lO3I 

Russia  Asiatic   

zz  t;ooo 

CC3727 

Turkey,  Asiatic  ....... 

6OOOO 

6OOOO 

60000 

6OOOO 

60000 

Total  Asia      

5,OO48l  I 

4,961604 

5-038995 

5-395758 

5,523976 

British  Africa     

27 

7SI 

4563 

54OO 

8892 

Egypt   . 

I   34875Q 

1,316212 

I.234.O84 

1,440107 

German  Africa  

2 

IOI 

1371 

1480 

1738 

62 

62 

Portuguese  Africa  

6l 

6 

179 

518 

ci8 

Sudan  (Anglo-Egyptian)       .     .     . 

6517 

6517 

15097 

I944I 

17782 

Total  Africa    

i  33781  i 

Total  Oceania     

93 

312 

123 

133 

1  08 

Grand  total     

NOTE.  The  total  area  of  hay  grown  in  the  United  States  varies  from  40 
to  50  million  acres,  the  production  varies  from  50  to  70  million  tons,  the 
average  value  varies  from  50x3  to  700  million  dollars,  and  as  a  ten-year 
average  (1900  to  1909)  the  yield  is  1.44  tons  per  acre  and  the  farm  price 
$9.59  per  ton. 


APPENDIX 


625 


COTTON  —  Continued 

COTTON  ACREAGE,  BY  STATES,  1902-1907  106 

[As  reported  by  Bureau  of  Statistics,  Department  of  Agriculture] 


STATE  OR  TERRITORY 

1903 

(Acres) 

1903 

(Acres) 

1904 

(Acres) 

1905 

(Acres) 

1906 

(Acres) 

1907 

(Acres) 

39864 

38664 

North  Carolina       .... 
South  Carolina  

1.076359 
2,205009 

1,155028 
2,318100 

1,306968 
2,531875 
4,227lS8 

1,085568 
2,161023 

1,374000 
2,389000 

1,408000 
2,426000 

Florida     

253288 

268666 

1,617678 

1,642463 

1,745865 

Texas  

7,8011578 

Arkansas  

1,901841 
754811 

1,925191 
/ 

783196 

2,05Il85 
88I34T 

1,718751 

2,097000 

1,950000 

59786 

418184 

Indian  Territory     .... 

657533 

702966 

813642 

816638 

901000 

£2,106000 

United  States      .... 

27,114103 

28,014860 

30,053739 

26,117153 

31,374000 

31,311000 

PRODUCTION  OF  COTTON,  IN  SCO-POUND  GROSS  WEIGHT  BALES,  BY  STATES,  AND  TOTAL 
VALUE  OF  CROP,  1902-1903  TO  1907-1908 

[As  finally  reported  by  U.S.  Census  Bureau] 


STATE  OR 
TERRITORY 

1902-3 

(Bales) 

1903-4 

(Bales) 

1904-5 

(Bales) 

1905-6 

(Bales) 

1906-7 

(Bales) 

1907-8 

(Bales) 

13862 

North  Carolina     .     . 
South  Carolina     .     . 
Georgia  

549542 
925490 

528707 
787425 

703760 
1,151170 
1,887853 

619141 

1,078047 
1,682555 

579326 
876181 
1,592572 

605310 
1,119220 
1,815834 

52386 

68797 

Alabama      .... 
Mississippi  .... 
Louisiana    .... 
Texas      
Arkansas     .... 

Tennessee    .... 
Missouri      .... 
Oklahoma   .... 
Indian  Territory  .     . 
All  other      .... 

956215 
1,443740 
882073 
2,498013 
970205 

3I7M9 

42255 
193784 
351508 
1263 

986221 
1,432796 
824965 
2,471081 
734593 

248996 
378i3 
186589 
278347 
772 

1,448157 
1,708017 
1,089^26 
3,145372 
930665 

329319 
51570 
335064 
469254 
2019 

1,238574 
1,198572 
513480 
2,541932 
619117 

278637 
42730 
326981 
350125 
1416 

1,261522 
1,530748 
987779 
4,174206 
941177 

306037 
54358 
487306 
410520 
2270 

1,112698 
1,468177 
675428 
2,300179 
774721 

275235 
36243 

[862383 
2734 

United  States    .     . 

10,630945 

9.851129 

13,438012 

10,575017 

13,273809 

11,107179 

Total  value  of  crop 

$421,687941 

$576,499824 

$561,100386 

$556,833817 

$640,311538 

$613,630436 

626 


APPENDIX 


INTERNATIONAL  TRADE  IN  OIL  CAKE  AND  OIL-CAKE  MEAL,  1902-1906 

EXPORTS 


COUNTRY 

YEAR 
BEGIN- 
NING 

1903 

(Lb.) 

1903 

(Lb.) 

1904 

(Lb.) 

1905 

(Lb.) 

1906 

(Lb.) 

Argentina  .... 
Austria-Hungary     . 
Belgium     .... 
Canada      .... 

Jan. 
an. 
Jan. 
July 
Jan. 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

Jan. 
Jan. 
Tan. 
July 

18,984000 
64,246433 
128,843692 
28,830032 
89,672067 

4,045586 
130,544487 
325,867127 
328,760326 
24,008481 

139,814583 
850,095204 
53,146240 
1,679,394359 
11,491000 

19,989308 
88,614781 
137,066773 
29,002624 
89,672067 

8,682295 
156,944836 
314,693035 
375,254222 
19,627750 

136,734208 
1,028,500994 
53,146240 
1,503,232680 
14,337000 

29,019439 
92,352938 
145,834669 
10,115392 
83,999467 

4,417928 
160,794106 
351,628964 
436,964238 
24,696396 

154,525289 
1,084,331094 
48,462400 
1,894,577648 
26,149000 

29,277380 
77,134433 
160,163061 
26,227376 
95,344667 

5,676571 
147,961001 
339,529396 
397,800450 
24,425228 

143,290470 
977,376790 
57,830080 
1,918,171984 
273,670241 

29,524298 
58,999874 
176,470002 
44,39736o 
120,944400 

3,101969 
164,142926 
323,482202 
361,592621 
12,617052 

147,620993 
1,152,431674 
58,524480 
2,063,732272 
i95,4579oi 

Denmark  .... 
Egypt    

France  
Germany   .... 
Italy      

Netherlands    .     .     . 

United  Kingdom 
United  States      .     . 
Other  countries  .     . 
Total      .... 

3,878,652617 

3,975,498813 

4,547,868968 

4,673,879128 

4,913,040024 

IMPORTS 


Austria  Hungary     . 
Belgium     .... 
Canada      .... 
Denmark   .... 
Dutch  East  Indies  . 

Finland      .... 
France  
Germany   .... 
Italy 

Jan. 
Jan. 
July 
Jan. 
Jan. 

Jan. 
Jan. 
Jan. 
Jan. 
Jan. 

Jan. 
Jan. 
Jan. 

7,656432 
353,641510 
3,521616 
654,111347 
15,691801 

12,594155 
238,507681 
1,074,490655 
7,909522 
55,550267 

461,470090 
142,046653 
861,678720 
21,898000 

21,750580 
421,696899 
3,808224 
7/6,875723 
15,977041 

7,205192 
279,980299 
1,108,355853 
9,645221 
78,582800 

476,967295 
163,633913 
811,798400 
25,702000 

27,340840 
445,202134 
3,953376 
757,481664 
31,004951 

13,948054 
292,015079 
1,231,409255 
6,525902 
82,023067 

495,921130 
219,913686 
823,934720 
54,076000 

26,469794 
448,216564 
2,308432 
842,875492 
19,075498 

11,179475 
323,719234 
1,285,529859 
5,209963 
110,074533 

510,951427 
226,374498 
779,368320 
153,688134 

24,769590 
510,213668 
3,656912 
846,259587 
26,850775 

14,543404 
237,725713 
1,325,622674 
7,851541 
134,060400 

564,097473 
264,890580 
797,115200 
112,894136 

Netherlands   .     .     . 
Sweden      .... 
United  Kingdom 
Other  countries  .     . 
Total      .... 

3.910,777449 

4,202,279440 

4,484,750758 

4,763,041223 

4,870,551653 

SECTION  V 

METHODS   OF   SOIL  ANALYSIS 

Collecting  soil  samples.  After  one  has  become  familiar  with  the 
typical  boring  of  the  soil  type  to  be  studied,  the  sample  is  collected  by 
taking  borings  from  10  to  20  different  places,  each  of  which  should  appear 
to  be  truly  representative  of  the  soil  type.  These  borings,  thoroughly 
mixed,  should  make  a  trustworthy  sample  for  analysis.  An  auger  about 
i£  inches  in  diameter,  with  the  screw  point  and  the  vertical  lips  filed  off, 


APPENDIX  627 

is  the  most  satisfactory  implement  to  use.  The  stem  may  be  cut  in  two 
and  a-  steel  rod  of  good  quality  welded  in  to  make  the  auger  about  40 
inches  long. 

Ordinarily,  samples  may  well  be  taken  in  sets  of  three :  the  surface,  or 
average  plowed  soil  (o  to  6|  inches),  the  subsurface,  or  that  which  can 
possibly  be  moved  with  a  subsoil  plow  (6§  to  20  inches),  and  the  subsoil 
(20  to  40  inches),  corresponding  to  about  2  million,  4  million,  and  6  mil- 
lion pounds,  respectively,  of  ordinary  soil.  The  surface  boring  is  made 
and  the  hole  enlarged  about  \  inch  in  diameter,  the  soil  all  being  saved. 
The  subsurface  boring  is  then  taken  and  the  hole  again  enlarged,  but  the 
extra  soil  is  not  saved.  Finally  the  subsoil  boring  is  taken  and  the  soil 
saved  from  only  one  half  (one  groove)  of  the  auger.  This  provides  about 
equal  quantities  of  soil  from  each  stratum. 

Preparation  of  sample.  The  sample  of  soil  after  air-drying  is  pul- 
verized to  pass  through  a  sieve  with  round  holes  i  mm.  in  diameter.  Any 
gravel  which  does  not  pulverize  as  easily  as  the  dried  lumps  of  clay  is 
weighed  and  its  percentage  determined,  after  which  it  is  discarded. 
For  all  determinations  except  reaction  and  acidity  the  soil  is  further 
pulverized  to  pass  through  a  zoo-mesh  sieve. 

Dry  matter.  Five  grams  of  soil  are  placed  in  a  glass  weighing  tube 
fitted  with  glass  stopper,  heated  for  eight  hours  at  a  temperature  of  105° 
to  107°  C.  in  a  current  of  air  dried  by  passing  through  H2SO4  and  CaCl2, 
the  stopper  replaced,  and  the  tube  allowed  to  cool  in  a  desiccator.  On 
weighing,  duplicate  samples  should  check  within  5  mg.  The  results  of 
all  analyses  are  calculated  to  the  dry  basis  as  found  by  this  determination. 

Reaction.  The  reaction  of  the  soil  is  determined  by  the  test  sug- 
gested by  Veitch  (Bulletin  73,  page  136,  Bureau  of  Chemistry,  United 
States  Department  of  Agriculture).  About  10  g.  of  soil  are  placed 
in  a  Jena  flask  with  150  cc.  water,  thoroughly  shaken,  and  allowed  to 
settle  until  the  water  is  practically  clear.  The  supernatant  liquid  is 
carefully  drawn  off  and  boiled  down  with  a  few  drops  of  phenolphtha- 
lein  in  a  Jena  beaker  (covered  with  a  watch-glass)  to  about  25  cc.  A  pink 
color  indicates  alkalinity.  If  no  color  appears,  the  soil  is  either  acid  or 
neutral.  In  case  the  soil  is  acid,  its  acidity,  calculated  to  calcium  car- 
bonate required  to  neutralize,  is  determined;  and  in  case  it  is  alkaline, 
the  carbonate  carbon  present  is  determined  and  calculated  to  calcium 
carbonate. 

Acidity.  Place  100  g.  of  soil  in  a  400  cc.  wide-mouthed  bottle,  add 
250  cc.  normal  potassium  nitrate  solution,  stopper,  and  shake  continu- 
ously for  three  hours  in  a  shaking  machine  or  every  five  minutes  by  hand. 
Let  stand  over  night.  Draw  off  125  cc.  of  the  clear  supernatant  liquid, 


628  APPENDIX 

boil  ten  minutes  to  expel  carbon  dioxid,  cool,  and  titrate  with  standard 
sodium  hydroxid  solution  (of  which  i  cc.  is  equivalent  to  4  mg.  of  cal- 
cium carbonate),  using  phenolphthalein  as  indicator. 

The  acids  and  acid  salts  of  the  soil  are  difficultly  soluble  in  water,  but 
by  treating  with  a  salt  solution,  as  potassium  nitrate,  a  double  decomposi- 
tion takes  place,  carrying  acidity  into  solution.  An  equilibrium  is  reached, 
however,  before  this  reaction  runs  to  an  end,  and  if,  after  having  drawn 
off  125  cc.  to  titrate,  125  cc.  of  fresh  potassium  nitrate  are  added  to  the 
bottle  and  the  bottle  again  shaken  for  three  hours,  125  cc.  drawn  off  will 
give  a  titration  which  is  more  than  one  half  of  the  first.  By  continuing 
this  process  until  the  last  125  cc.  shows  practically  no  acidity,  we  have  a 
series  of  titrations  the  sum  of  which  represents  the  total  acidity  of  the 
100  g.  of  soil.  It  has  been  found  by  working  with  a  number  of  different 
soils,  that  as  an  average  the  sum  of  such  a  series  is  2^  times  the  first  ti- 
tration. Consequently,  when  the  sodium  hydroxid  is  made  up  so  that 
i  cc.  is  equivalent  to  4  mg.  of  calcium  carbonate,  and  125  cc.  (which 
represents  50  g.  of  soil)  are  titrated,  each  o.i  cc.  required  to  neutralize 
corresponds  to  i  mg.  of  calcium  carbonate  required  by  the  100  g.  of  soil, 
or  to  o.ooi  per  cent  of  calcium  carbonate  required  by  the  soil  tested. 

The  titrations  of  duplicate  samples  should  not  differ  more  than  0.8  cc. 
for  soil  samples  requiring  less  than  100  cc.  NaOH. 

Carbonate  carbon.  Carbonate  carbon,  when  present,  is  determined 
volumetrically  in  the  apparatus  used  for  total  carbon,  described  and 
illustrated  in  the  Journal  of  the  American  Chemical  Society,  Vol.  26, 
pages  294  and  1640,  by  treating  the  air-dried  soil  with  dilute  (i :  i)  hydro- 
chloric acid  and  measuring  the  gas  evolved  both  before  and  after  absorp- 
tion of  carbon  dioxid  in  an  alkali  pipette  containing  a  33  per  cent  solu- 
tion of  potassium  hydroxid.  The  size  of  sample  used  for  this  test  varies 
(according  to  the  amount  of  calcium  carbonate  present)  between  two  and 
ten  grams.  Duplicate  tests  of  ordinary  soils  not  very  high  in  inorganic 
carbon  should  check  within  0.2  to  0.4  cc.  These  results  are  calculated 
to  and  reported  as  calcium  carbonate  present. 

Corrections  must  be  made  for  pressure  and  temperature,  and  absorp- 
tion of  carbon  dioxid  should  be  repeated  to  a  constant  reading;  also 
the  gas  should  be  allowed  to  stand  for  three  minutes  before  the  initial  and 
the  final  readings. 

Organic  carbon.  The  total  carbon  of  the  soil  is  determined  by 
means  of  Parr's  apparatus  *  as  modified  by  Pettit 2  to  contain  an  absorp- 
tion pipette  of  potassium  hydroxid. 

1  Jour.  Am.  Chem.  Soc.,  Vol.  26,  p.  294.  *  Ibid.,  p.  1640. 


APPENDIX  629 

Two  grams  of  ordinary  soil  (or  \  to  i  g.  of  peaty  soil)  are  placed  to- 
.gether  with  10  g.  of  sodium  peroxid  in  the  Parr  explosion  bomb,  0.7 
to  i  g.  (ordinarily  about  0.8  g.)  powdered  magnesium  added  to  start 
combustion,  the  whole  thoroughly  mixed  by  shaking,  and  the  charge 
exploded  by  means  of  a  hot  iron  plug  or  an  electric  current.  (.7  g. 
magnesium  is  used  with  soils  high  in  organic  matter.)  The  contents 
of  the  bomb  are  then  washed  into  a  beaker  by  means  of  a  fine  stream  of 
hot  water  and  brought  to  a  boil  to  break  up  the  coarse  particles  and  expel 
as  much  oxygen  as  possible.  It  is  then  run  from  a  separatory  funnel  into 
a  flask  containing  dilute  sulfuric  acid  (i  H2SO4  to  2  H2O)  and  the  gas 
collected  in  a  measuring  pipette.  When  all  of  the  sample  has  been  added 
to  the  sulfuric  acid  and  boiled  until  it  is  decomposed,  the  flask  is  filled 
with  water  through  the  separatory  funnel  to  force  the  last  of  the  gas  into 
the  measuring  pipette.  After  noting  the  volume,  the  carbon  dioxid  is 
absorbed  in  the  potassium  hydroxid  pipette  and  the  volume  again  read. 
In  taking  the  initial  and  the  final  readings,  the  same  precaution  should 
be  taken  as  for  carbonate  carbon.  Duplicate  samples  should  check 
within  i  cc.  for  every  100  cc.  gas  obtained,  and  corrections  must  be  made 
for  pressure  and  temperature. 

A  blank  determination  must  be  run  on  the  sodium  peroxid,  and  this  is 
best  done  by  using  first  a  2-gram,  then  a  i-gram  sample  of  the  same  soil, 
calculating  the  amount  of  carbon  in  the  reagents  from  the  difference  in 
results,  e.g. 

Let  x  =  carbon  in  reagents ; 

then,  if  2  g.  soil  +  x  =  45  mg.  C, 

and  i  g.  soil  +  x  =  25  mg.  C, 

we  get  by  multiplying  the  last  equation  by  2 

2  g.  soil  +  2  x  =  50  mg.  C, 

and,  subtracting  the  first  equation  from  this,  we  get 

x  =  5  mg.  C 

Much  better  results  can  be  obtained  by  determining  the  blank  in  this 
way  than  where  no  soil  is  used. 

The  total  carbon  thus  found  minus  the  carbonate  carbon  is  reported  as 
organic  carbon  and  is  taken  as  a  measure  of  the  organic  matter  present 
in  the  soil. 

Nitrogen.  Nitrogen  is  determined  by  the  regular  Kjeldahl  method. 
Ten  grams  of  soil  (5  g.  if  high  in  nitrogen)  are  weighed  into  a  Kjeldahl 
flask,  20  cc.  sulfuric  acid  (more  if  necessary)  and  approximately  .65  g. 


630  APPENDIX 

metallic  mercury  added  and  the  contents  of  the  flask  digested  until  color- 
less. Oxidation  is  completed  by  adding,  while  stjll  boiling  hot,  powdered 
potassium  permanganate  until  the  solution  is  green.  It  is  then  allowed 
to  cool  and  transferred  with  250  cc.  of  nitrogen-free  water  to  a  copper 
flask  of  about  700  cc.  capacity  and  enough  strong  alkali  solution  l  added 
to  more  than  neutralize  the  acid.  The  flask  is  then  immediately  con- 
nected with  a  still,  the  ammonia  distilled  off  and  collected  in  a  flask 
containing  a  measured  amount  of  standard  hydrochloric  acid.  The  ex- 
cess of  hydrochloric  acid  is  then  titrated  back  with  standard  ammonium 
hydroxid,  using  lacmoid  as  indicator,  and  the  amount  of  nitrogen  in  the 
soil  calculated.  A  convenient  strength  of  ammonia  solution  is  one  in 
which  i  cc.  is  equivalent  to  .0032  g.  nitrogen. 

Duplicates  should  check  within  0.2  cc.  A  blank  determination  must 
be  run,  by  using  approximately  .5  g.  pure  sugar  instead  of  the  soil  sample, 
and  a  correction  made  for  the  nitrogen  in  the  reagents  used. 

Phosphorus.  For  the  phosphorus  determination  the  soil  is  decom- 
posed by  heating  with  sodium  peroxid  as  given  on  page  145,  Bulletin 
105,  Bureau  of  Chemistry,  U.  S.  Department  of  Agriculture. 

Five  grams  of  ordinary  soil  are  thoroughly  mixed  with  10  g.  of  sodium 
peroxid  in  an  iron  crucible  of  about  no  cc.  capacity,  the  flame  applied 
directly  to  the  surface  just  long  enough  to  start  the  action,  the  crucible 
covered,  and  the  heating  continued  over  a  low  flame  for  twenty-five 
minutes.  The  tip  of  the  flame  should  just  touch  the  bottom  of  the 
crucible  and  the  heat  be  kept  low  enough  so  the  peroxid  will  not  fuse. 
In  decomposing  a  soil  very  low  in  organic  matter,  such  as  some  subsoils, 
o.i  to  0.5  g.  of  powdered  sugar  should  be  added  to  favor  the  reaction. 

Peat  soils  are  usually  high  in  phosphorus,  and  2\  g.  are  sufficient  for 
the  determination.  Such  soils,  high  in  organic  matter,  will  not  fuse 
slowly  when  heated  with  peroxid,  but  by  moistening  the  sample  with  5  cc. 
of  calcium  acetate  of  sufficient  strength  to  fix  the  phosphorus,  the  organic 
matter  can  be  safely  burned  off,  and  after  cooling,  enough  sugar  added  to 
effect  decomposition  with  sodium  peroxid  in  the  usual  way. 

After  decomposition,  the  sample  is  washed  into  a  beaker,  the  coarser 
particles  broken  up,  then  transferred  to  a  500  cc.  flask  acidified  with 
hydrochloric  acid  and  boiled  for  five  minutes.  A  little  strong  nitric  acid 
is  added  to  insure  complete  oxidation  of  the  iron  to  the  ferric  condition. 
It  is  then  allowed  to  cool  and  made  up  to  volume.  There  should  be  no 
undecomposed  soil  in  the  bottom  of  the  flask.  The  silica  is  allowed  to 

1  Containing  60  Ib.  Greenbank's  alkali  and  800  g.  potassium  sulfid  for  each  30 
litres  of  water. 


APPENDIX  631 

settle  over  night,  200  cc.  of  the  clear  supernatant  solution  drawn  off,  and 
the  iron,  aluminum,  and  phosphorus  precipitated  by  adding  ammonium 
hydroxid  to  the  boiling  solution.  If  there  is  not  enough  iron  present  to 
give  a  very  decided  brown  color  to  the  precipitate,  a  little  ferric  chlorid 
should  be  added  before  precipitation  to  insure  complete  removal  of  the 
phosphorus  from  solution.  The  precipitate  is  filtered  off,  washed 
5  times,  dissolved  with  warm  dilute  nitric  acid,  evaporated,  and  heated 
on  the  steam  bath  to  dehydrate  the  silica,  taken  up  with  strong  nitric 
acid,  heated,  then  diluted,  and  the  silica  filtered  off.  The  filtrate  is 
evaporated  to  about  5-10  cc.,  care  being  taken  that  it  does  not  go  to 
dryness,  as  alumina  and  some  silica  are  almost  sure  to  separate  out  and 
cause  trouble.  It  is  then  completely  neutralized  with  ammonia,  cleared 
up  with  nitric  acid,  approximately  i  g.  of  crystalline  ammonium  nitrate 
added,  and  the  phosphorus  precipitated  at  4o°-5o°  with  15  cc.  ammo- 
nium molybdate  solution,  allowing  it  to  stand  on  the  water  bath  at  this 
temperature  for  one  to  two  hours,  stirring  occasionally  for  the  first  15 
or  20  minutes.  It  is  then  allowed  to  stand  at  room  temperature  over 
night,  the  precipitate  filtered  off  through  a  double  filter  and  washed 
with  a  tenth-normal  solution  of  ammonium  nitrate  until  free  from 
molybdic  acid  and  finally  twice  with  cold  distilled  water.1  It  is  then 
removed  together  with  the  filter  paper  to  a  beaker,  dissolved  with  a 
measured  excess  of  standard  potassium  hydroxid  solution,  and  the 
excess  titrated  back  with  standard  nitric  acid . 

A  very  convenient  strength  of  potassium  hydroxid  solution  is  .83236  g. 
KOH  per  100  cc.  One  cubic  centimeter  is  then  equivalent  to  0.2  mg. 
of  phosphorus. 

The  nitric  acid  should  be  made  equivalent  in  strength  to  the  potassium 
hydroxid,  and  with  these  strengths  of  solutions,  duplicates  should  check 
within  0.2  cc. 

A  blank  determination  must  be  run,  using  no  soil,  and  a  correction 
made  for  the  phosphorus  found  in  the  reagents. 

(Ammonium  molybdate  solution  is  made  by  dissolving  100  g.  molybdic 
acid  in  400  cc.  NH4OH  (sp.  gr.  .96)  and  adding  very  slowly  to  1250  cc. 
HNO3  (sp.  gr.  i. 20),  keeping  the  solution  cool  and  well  stirred.) 

Total  potassium.  This  test  is  carried  out  as  given  on  page  147,  Bulle- 
tin 105,  Bureau  of  Chemistry,  Department  of  Agriculture.  One  gram 
of  soil,  one  gram  of  ammonium  chlorid,  and  eight  grams  of  calcium 

1  Molybdic  oxid  is  often  precipitated  if  the  first  few  washings,  while  iron  is  still 
present,  are  done  with  either  water  or  ammonium  nitrate  solution.  This  may  be 
prevented  by  washing  two  or  three  times,  until  free  of  iron,  with  ammonium  nitrate 
containing  a  little  of  the  ammonium  molybdate  solution. 


632  APPENDIX 

carbonate  are  fused  as  directed  in  Fresenius'  "Quantitative  Analysis," 
page  426,  and  by  Hillebrand  in  Bulletin  305  of  the  United  States  Geo- 
logical Survey,  where  an  illustration  of  the  apparatus  is  given.  The 
fused  mass  is  transferred  to  a  porcelain  dish,  slacked  with  hot  water, 
finely  ground  with  an  agate  pestle  and  transferred  to  a  filter.  After 
washing  with  about  600  cc.  hot  water,  the  filtrate  and  washings  are  run  to 
dryness  in  a  Jena  beaker,  taken  up  with  hot  water  and  again  filtered, 
acidified  with  hydrochloric  acid,  concentrated  to  about  10  cc.,  and  i^  cc. 
of  a  platinum  chlorid  solution  (10  cc.  containing  i  g.  platinum)  added. 
This  is  then  evaporated  to  a  sirupy  consistency,  taken  up  and  washed 
about  fifteen  times  with  80  per  cent  alcohol,  three  times  with  ammonium 
chlorid  solution,  and  again  fifteen  times  with  alcohol.  The  precipitate 
is  then  washed  through  the  filter  with  hot  water  into  a  platinum  dish, 
evaporated  on  the  steam  bath  to  dryness  and  heated  in  an  air  .oven  at 
110°  C.  for  an  hour,  cooled  in  a  desiccator,  and  weighed.  Duplicate 
samples  should  not  differ  more  than  1.5  mg.  in  the  final  weight. 

A  correction  must  be  made  for  the  amount  of  potassium  in  the  reagents 
which  is  found  by  making  a  blank  determination,  using  no  soil. 

(Ammonium  chlorid  solution  is  made  by  dissolving  200  g.  NH4C1  in 
1000  cc.  water  and  saturating  with  K2PtCl6.) 

Calcium.  Decompose  2  g.  of  soil  (less  if  high  in  calcium)  by  heating 
with  6  to  8  g.  of  sodium  peroxid  in  an  iron  crucible ;  transfer  with  water, 
acidify  with  hydrochloric  acid,  evaporate  to  dryness ;  and  continue  heat- 
ing for  about  an  hour,  on  the  steam  bath,  to  dehydrate  the  silica.  Digest 
the  residue  with  hydrochloric  acid  on  the  steam  bath  until  all  that  will 
has  gone  into  solution  (about  ten  minutes  will  usually  suffice) ;  filter,  and 
wash  free  from  chlorids  with  hot  water.  Bring  the  filtrate  and  washings 
to  about  150  cc. ;  add  .5  g.  ammonium  persulfate,  heat  to  boiling;  and 
add  ammonia  in  excess  to  precipitate  iron,  aluminum,  phosphorus,  and 
manganese.  After  boiling  about  five  minutes,  filter  while  still  boiling  hot, 
and  wash  with  hot  water  till  practically  free  from  chlorids ;  acidify  with 
hydrochloric  acid,  evaporate  to  about  100  cc.,  add  i  cc.  of  a  6  per  cent 
solution  of  ferric  chlorid  and  about  .5  g.  of  ammonium  persulfate ;  heat 
to  boiling,  precipitate  with  ammonia  in  decided  excess,  boil  for  several 
minutes ;  then  filter  and  wash  as  before.  Bring  the  filtrate  and  washings 
to  a  volume  of  about  150  cc. ;  boil,  and  to  the  boiling  solution  add  slowly, 
and  with  constant  stirring,  enough  concentrated  ammonium  oxalate 
(5  to  10  cc.)  to  precipitate  the  calcium  and  to  change  the  magnesium  to 
the  oxalate.  Digest  for  an  hour  or  more  on  the  steam  bath,  care  being 
taken  that  the  volume  does  not  go  below  75  cc. ;  filter,  and  wash  free  from 
chlorids  with  hot  water.  (As  a  rule,  one  precipitation  of  calcium  is 


APPENDIX  633 

sufficient.)     Burn  the  filter  and  ignite  the  precipitate  in  the  blast  to  con- 
stant weight.     Weigh  as  calcium  oxid  and  compute  to  calcium. 

Magnesium.  Evaporate  to  dryness  the  filtrate  and  washings  from  the 
calcium  determination;  wash  the  residue  with  hot  water  into  a  long- 
neck  Jena  flask;  remove  ammonium  salts  by  boiling  to  a  small  volume 
with  nitric  and  hydrochloric  acids  (about  25  cc.  of  each),  adding  more  of 
the  acids  (10  to  15  cc.  of  each)  two  or  three  times,  and  finally  evaporating 
nearly  or  quite  to  dryness.  Transfer  the  remaining  salts  to  a  beaker 
with  hot  water ;  add  enough  ammonium  chlorid  to  prevent  the  precipita- 
tion of  magnesium  hydroxid,  make  alkaline  with  ammonia,  and  then  add 
.5  g.  ammonium  persulfate;  digest  on  the  steam  bath  for  30  minutes, 
taking  care  that  there  is  always  an  excess  of  ammonia  present;  filter, 
and  wash  free  from  chlorids  with  hot  water.  Concentrate  the  filtrate  and 
washings  to  about  50  or  75  cc.,  acidify  with  hydrochloric  acid,  and  add 
5  to  10  cc.  of  a  normal  solution  of  NH4NaHPO4  to  insure  the  precipita- 
tion of  all  magnesium.  While  stirring  vigorously  and  taking  care  not  to 
strike  or  rub  the  sides  of  the  beaker,  slowly  add  enough  ammonia  to 
make  the  solution  distinctly  alkaline.  After  30  minutes,  add  10  cc.  of 
strong  ammonia,  slowly  and  with  vigorous  stirring ;  cover  closely  to  reduce 
the  escape  of  ammonia,  and  let  stand  for  12  hours.  Then  filter,  and 
wash  the  precipitate  free  from  chlorids,  using  i\  per  cent  ammonia  water. 
Dry  the  filter,  burn  at  a  moderate  heat,  and  then  ignite  intensely  to  con- 
stant weight,  using  the  blast.  Weigh  as  magnesium  pyrophosphate  and 
compute  to  magnesium. 

NOTE.  In  all  cases  the  above  determinations  relate  to  the  total  amounts 
present  in  the  soil.  If  much  alkali  or  other  soluble  salts  are  present,  the  amount 
may  be  determined  by  extracting  with  water,  evaporating,  and  weighing  the 
residue,  which  may  be  analyzed  subsequently  if  desired.  The  author  does  not 
advise  the  analysis  of  soils  by  determining  only  the  "acid-soluble"  portion  of 
the  constituents,  —  a  method  which  involves  five  arbitrary  conditions:  (i)  the 
choice  of  solvent,  (2)  the  strength  of  solvent,  (3)  the  relative  amounts  of  soil  and 
solvent,  (4)  the  time  of  digestion,  and  (5)  the  temperature  of  digestion.  To 
change  any  one  of  these  arbitrarily  fixed  conditions  may  change  the  amount  of 
soil  constituents  dissolved.  Such  analyses  furnish  little  information,  and  they 
tend  to  discredit  the  very  exact  and  highly  serviceable  science  of  chemistry- 

Pot-culture  experiments  by  the  Illinois  Experiment  Station  have  shown  that 
crops  can  be  grown  in  the  "insoluble  residue,"  from  ordinary  acid  digestion  of 
soils,  without  addition  of  potassium;  and  they  markedly  improve  by  green 
manuring. 


634  APPENDIX 

SECTION   VI 

COMPOSITION  OF   SOME  EUROPEAN    SOILS 

THE  data  relating  to  the  composition  of  European  soils  are  very 
incomplete,  and  the  analytical  methods  used  have  been  far  from  uniform. 
A  good  compilation  of  these  data  from  Germany,  France,  and  the  United 
Kingdom  is  contained  in  Bulletin  57  (1909)  of  the  United  States  Bureau 
of  Soils,  giving  principally  the  results  secured  by  digesting  the  soils 
with  strong  acids.  This  compilation  includes  no  nitrogen  determina- 
tions, but  the  phosphorus,  potassium,  and  calcium  are  usually  given, 
and  sometimes  the  magnesium,  chiefly  in  terms  of  the  oxids. 

In  the  Rothamsted  laboratories,  after  previous  ignition  of  the  soil, 
very  strong  hot  hydrochloric  and  nitric  acids  are  employed  in  soil 
analysis,  and  probably  this  method  is  used  quite  generally  in  Great 
Britain.  If  so,  the  data  for  phosphorus  will  closely  approach  the  total. 
In  Germany  cold  hydrochloric  acid  is  the  common  solvent  used,  and 
the  results  thus  secured  are  not  comparable  with  those  of  England. 

Four  analyses  by  Burguy  (Inaug.-Diss.  Berlin,  1899)  show  as  an  aver- 
age 41,330  pounds  of  potassium  (evidently  total)  in  two  million  of  the 
loess  soil  of  North  Germany.  (The  phosphorus  content  of  this  soil  is 
not  given.)  About  450  analyses  of  German  soils  are  reported  in  this 
compilation,  but  for  the  reason  given  above  they  signify  but  little  to  the 
student  of  permanent  agriculture.  Wohltmann,  as  Director  of  the  Insti- 
tute for  Soil  and  Crop  Investigations,  Bonn-Poppelsdorf,  in  a  report 
(1901)  on  "The  Fertility-Invoice  of  West-German  Soils"  ("Das  Nahr- 
stoff-Kapital  West-Deutscher  Boden"),  shows  that  the  cold  acid  which 
he  used  generally  dissolved  about  one  fourth  as  much  potassium  from 
soils  as  hot  acid  (which  he  also  used  for  additional  potassium  deter- 
minations), but  the  proportion  varied  with  different  soils  from  about 
one  seventh  to  one  half.  A  trial  with  a  single  soil  showed  that  digestion 
with  hot  acid  for  12  hours,  dissolved  one  third  more  phosphorus  than 
digestion  with  cold  acid  for  48  hours ;  and  numerous  other  experiments 
have  shown  that  as  an  average  the  ordinary  10  hours'  digestion  with 
hot  hydrochloric  acid  will  dissolve  only  85  per  cent  of  the  total  phos- 
phorus, and  with  some  soils  less  than  one  half  of  the  total  is  thus  dis- 
solved. 

Wohltmann  concludes  from  extended  chemical  and  cultural  investiga- 
tions that  in  West  Germany  soils  which  contain  less  than  1200  pounds 


APPENDIX  635 

(in  two  million)  of  phosphorus  soluble  in  cold  hydrochloric  acid  are  in 
need  of  phosphorus  fertilizer  ("  ersatzbedurf tig  in  Phosphorsaure"). 

The  compiled  data  from  France  include  about  1550  soil  analyses,  but 
here  also  only  the  plant  food  dissolved  by  the  acid  used  is  reported,  and 
no  information  is  given  concerning  the  strength  of  acid,  time,  or  tem- 
perature. While  these  results  may  have  some  value  for  purposes  of 
comparison  among  themselves,  they  are  of  little  or  no  value  for  compari- 
son with  the  total  amounts  of  plant  food  contained  in  other  soils.  Fur- 
thermore this  great  mass  of  data  relates  to  the  soil  of  only  a  few  prov- 
inces. There  are  in  all  eighty-seven  different  provinces,  or  counties,  in 
France,  and  705  of  the  soil  samples  reported  upon  were  collected  in  the 
one  province  of  Aisne,  while  674  others  were  collected  in  Pas-de-Calais 
and  Loire-Inferieure,  and  129  more  in  three  other  provinces.  The 
remaining  42  samples  represent  six  additional  provinces,  leaving  seventy- 
five  provinces  from  which  no  soil  analyses  are  reported.  Practically 
all  of  the  1550  soil  samples  were  evidently  collected  about  1890  or 
before,  and  no  information  is  given  in  the  compiler's  report  to  show 
whether  they  are  supposed  to  represent  good  land  or  poor  land,  although 
in  one  case  a  single  field  is  represented  by  analyses  of  73  samples  of  soil. 

In  considering  the  analyses  of  European  soils,  it  may  well  be  kept  in 
mind  that  there  are  still  to  be  found  areas  of  "abandoned"  land  even  in 
western  Europe,  and  chemical  analyses  of  these  soils  are  often  made 
before  attempting  to  bring  them  back  into  agricultural  use  by  means 
of  fertilizers  and  manures.  Thus  the  marked  differences  in  the  plant- 
food  content  of  different  soils  in  England  may  serve  best  as  an  index 
of  the  agricultural  history  of  the  farms  with  respect  to  the  past  use  of 
bones,  guanos,  phosphates,  etc.,  while  in  America  such  differences  apply 
not  so  much  to  individual  farms,  fields,  or  plots  (see  Table  73,  page  411), 
but  rather  to  types  of  soil  more  or  less  modified  in  the  older  States  by 
the  general  and  almost  invariable  practice  of  gradual  soil  depletion. 

The  data  showing  the  phosphorus  content  of  soils  from  Great  Britain 
make  a  contribution  of  probable  value,  (i)  because  approximately  the 
total  amount  is  reported,  and  (2)  because  the  soil  formation  is  frequently 
recorded.  In  the  case  of  Dorset  County,  the  samples  appear  to  have 
been  collected  in  connection  with  some  sort  of  systematic  survey  or 
classification,  as  indicated  by  the  records  and  also  the  reference:  "Fifth 
Annual  Report  on  the  Soils  of  Dorset,  University  College,  Reading, 
1003." 

The  compiler  has  combined  the  calcium  found  in  limestone  (cal- 
cium carbonate)  with  that  reported  in  other  forms,  so  that  the  calcium 
data  have  too  little  value  to  justify  their  reproduction  here.  It  may  be 


636  APPENDIX 

stated,  however,  that,  of  the  286  samples  of  soil  reported  below,  129 
contained  an  amount  of  acid-soluble  calcium  which  if  present  as  car- 
bonate would  represent  10  tons  or  more  of  limestone  per  acre  in  the 
plowed  soil,  and  of  these  about  60  apparently  contained  more  than  50 
tons  per  acre  of  calcium  carbonate,  thus  suggesting  the  British  farmer's 
common  appreciation  of  the  importance  of  having  limestone  in  the  soil. 

The  following  table  shows  the  phosphorus  reported  for  each  of  these 
286  samples  of  soil,  and  the  data  certainly  indicate  that  Liebig's  ac- 
count of  the  tendency  (even  then  apparent)  toward  the  accumulation 
of  phosphorus  in  British  soil  was  well  founded.  As  a  general  average 
of  all  analyses,  it  will  be  seen  that  the  soil  of  England  now  contains  about 
twice  as  much  phosphorus  as  the  most  common  Illinois  corn-belt  land 
(brown  silt  loam),  three  times  as  much  as  the  ordinary  wheat-belt  soil 
of  southern  Illinois  (gray  silt  loam  on  tight  clay),  and  from  four  to 
fifteen  times  as  much  as  the  depleted  or  abandoned  lands  of  the  Atlantic 
Coastal  Plain  (such  as  the  Leonardtown  loam  and  Norfolk  loam,  the 
latter  belonging  to  a  series  of  thirteen  soil  types  already  represented  by 
surveyed  areas  aggregating  about  10  million  acres,  of  which,  however, 
soil  analyses  have  been  reported  for  only  two  types,  as  shown  in  Table 
22,  page  138). 

The  amount  of  phosphorus  in  2  million  pounds  of  surface  soil  varies 
in  the  Gault  soils  of  Kent  County  from  330  to  2210  pounds;  in  the  chalk 
soils  from  820  (Kent  County)  to  6800  pounds  (Dorset  County) ;  in  the 
Kimmeridge  clay  from  810  pounds  (Cambridgeshire)  to  7760  pounds 
(Dorset  County) ;  and  in  the  London  clay  from  460  pounds  (Surrey 
County)  to  4100  pounds  (Dorset  County).  Contrasted  with  these  vari- 
ations, the  records 1  of  analysis  of  555  samples  of  Illinois  soils,  in- 
cluding surface,  subsurface,  and  subsoil,  show  an  extreme  variation  from 
540  to  2780  pounds  of  phosphorus  in  2  million  pounds  of  soil,  the  late 
Wisconsin  yellow-gray  silt  loam  varying  from  540  pounds  in  2  million 
of  the  subsurface  to  900  pounds  in  the  surface,  and  the  early  Wisconsin 
black  clay  loam  varying  from  980  pounds  in  2  million  of  the  subsoil  to 
2780  in  the  surface. 

1  University  of  Illinois  Agricultural  Experiment  Station  Bulletin  123  (1908),  pp. 
262-294. 


APPENDIX 


637 


PHOSPHORUS  IN  SOILS  IN  THE  UNITED  KINGDOM 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6f  Inches  Deep) 


DESCRIPTION  AND  LOCALITY 
(Original  Sample  Nos.  ) 

PHOS- 
PHORUS 
(Lb.) 

DESCRIPTION  AND  LOCALITY 
(Original  Sample  Nos.) 

PHOS- 
PHORUS 
(Lb.) 

ENGLAND 


Berkshire 
Sutton's    seed    trial    grounds, 

Cheshire 
(i)       

870 

Reading     

T.2T.O 

(2) 

w  fw 
262O 

o  o 

Cambridge 

Cumberland, 

Hatley  plot  (3)       
Joint  rotation  (9)    .... 

3400 

1920 

Rose-bank  plot  (497)      .     .     . 
(499)      •     •     • 

440 

440 

Burgoyn's  (Univ.  Farm)  : 

(501)      .     .     . 

440 

17*    1  A 

*Tyr\ 

rieius  II  13       

720 

Fields  14-15       

1210 

Fields  16-17       

1920 

Dorset 

Fields  18-19      

790 

Alluvium  (38)  

S66o 

Bowlder  clay: 

(62)  . 

o 

2OIO 

Above  gault  (14) 

1220 

(41)  

4OIO 

Above  green  sand  (19)     .     . 

990 

Above  gault  (20)    .... 

93° 

Gravel  (36)            

27QO 

Above  gray  chalk  (21)     .     . 

890 

(?7) 

/  y 
2440 

Gault  soils  (3)    

1220 

\o// 

(6?) 

T'T' 
227O 

(7)    

IIIO 

(64) 

/ 
I74O 

(8)   ...... 

850 

/  ^ 

Kimmeridge  clay  soils  (12) 
(iS)      • 
(i?)      • 

1280 
850 

810 

Bagshot  beds  (83)      .... 
(30)      .... 
(40)      .... 
(65)      .... 

1570 
2l80 
1740 
1050 

Ampthill  clay  soils  (6)    ... 

840 

London  clay  (80)  

2790 

Oxford  clay  soils  (10)     .     .     . 

1030 

(12)  

/XO\ 

4IOO 

(11)     •     •     • 

1260 

(68)  

1310 

(22)     .     .     . 

1  200 

Reading  beds  (81)      .... 

2880 

Lower  greensand  soils     (5)     . 

1780 

(n)      .... 

3490 

(23)     • 

2260 

(67)      .... 

I830 

(18)     . 

1720 

(61)  ..... 

9CO 

(9)     • 

1470 

Junction    Reading    beds    and 

(6} 

1  720 

chalk  (T.Q) 

T,  66<D 

\\j) 

O 

APPENDIX 

PHOSPHORUS  IN  SOILS  IN  THE  UNITED  KINGDOM  (Continued) 
(Pounds  per  Acre  in  2  Million  of  Soil  (about  6f  Inches  Deep) 


DESCRIPTION  AND  LOCALITY 
(Original  Sample  Nos.) 

PHOS- 
PHORUS 
(Lb.) 

DESCRIPTION  AND  LOCALITY 
(Original  Sample  Nos.) 

PHOS- 
PHORUS 
(Lb.) 

ENGLAND  (Continued) 


Dorset  (continued) 
Chalk    (15)       

2620 

253° 
6800 
4100 
2880 
4270 
2090 

3r4° 
2880 

2350 
2700 
2180 

445° 
3840 

3T4° 
2700 
2270 

323° 

5230 
6890 

2OIO 

2790 

2440 

2700 
3840 

253° 
2440 
4360 

253«> 

375° 

1310 

5230 
7760 

33io 
2090 

Dorset  (continued) 

Kimmeridge  clay  (87)     .     .     . 
(88)     .     .     . 

2960 
4360 

2700 
2790 
4100 
5230 
3490 
3050 
2790 

2700 

33!° 
33*° 
2960 

2OIO 
2880 
2790 
2180 
3920 

4270 
3920 
2530 
3920 
2270 

2350 
2620 
2700 
1480 

5580 
3230 

2960 

3T4° 
2180 

33io 
4270 

5230 

(71) 

(99)       

(95)       

(T7\ 

(51)       

\ll)     

(Q~\ 

(94)       

(°2)  

(Q.r.\ 

(35)       

V89.'    
(%} 

(50)       

(0)    

fe*,} 

(16)       

157J  
feS\ 

(72)       

(5°)  
Calcareous  grit  (9)     .... 

(40)                          .     . 

(21)       

doo) 

(34)    
(60)    

(59)    
(52)    
(53)    
(29)    
(4)   

Cornbrash  (10)      

d) 

(08) 

(Q6) 

(97)        .... 

Greensand  (79)      

(47)      
(48)     
(2)      

Junction  greensand  and  marl- 
stone  (31) 

(76)      
(28)      .-    . 

Fuller's  earth  (18)      .... 
(23)       .... 
(56)      .... 
(46)      .... 
(90)      .... 
(26)      .... 

Inferior  oolite  (91)     .... 
(13)     .... 

[unction    inferior    oolite    and 
Midford  sands  (14)       .     . 

Midford  sands  (55)    .... 
(54)    .... 
(45)    .... 
(5)    .... 
(92)    .... 

(a«) 

Wealden  beds  (33)     .... 
(32)     .... 
(84)     .... 
(69)     .... 

(22)       .... 

Purbeck  beds  (27)     .... 
Portland  stone  (66)    .... 

Kimmeridge  clay    (3)    ... 
(20)    .     .     . 
(42^     .     .     . 

(85)     •     •     • 
(86)     ... 

APPENDIX 


639 


PHOSPHORUS  IN  SOILS  IN  THE  UNITED  KINGDOM  (Continued) 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6f  Inches  Deep) 


PHOS- 

DESCRIPTION AND  LOCALITY 

DESCRIPTION  AND  LOCALITY 

(Original  Sample  Nos.) 

PHORUS 
(Lb.) 

(Original  Sample  Nos. 

PHORUS 

(Lb.) 

ENGLAND  (Continued) 


Dorset  (continued) 

Junction   Midford  sands  and 
marlstone  (6)      .... 
(43)      ..-• 

Marlstone    (7)      

(70)      
(75)      
(78)      

Junction  marlstone  and  lower 
Lias  (24)    . 

270x3 
2790 

4270 

549° 
2880 
4100 

253° 
3°5° 

349° 

4450 
4620 

Essex  (continued) 
Saffron  Walden   ]       .... 
Tendring      

960 
870 
780 

1400 
1130 
780 
1310 

Thaxted       

St.  Osyth      

Yeldham      

Hampshire 

Newlands  Manor,  Lymington 
(4) 

1480 
1260 

(44)    • 

Lower  Lias  (17)    

West  Mark,  near  Petersfield  (5) 

(74)    
(93)    

Isle  of  Ely 

Black  soils: 
White  Fen  Benwick    .     .     . 
Littleport  Fen    .     .     . 

2670 
2480 
3770 

334° 

2300 
3260 

1950 

2140 
1670 

Durham 

Grange  Hill  plot  (116)    .     .     . 
Shield  Ash  plot        (i)    .     .     . 
(11)    •     •     • 

1130 

79° 
1130 

Wryde           

Loam,  Wisbeck  Fen  .... 

f 

Essex 
Birch  

870 
870 

157° 
1400 

1220 
2090 

7<X) 
IQ2O 
1740 

Clays,  Wryde  ] 
Silts  Wryde      

Burnham      

Silts,  Needham    j 

Kent 

London  clay: 
Whitsable      

1040 
970 

1250 

Gosfield    { 

Orsett 

Sheorjev    • 

Ramsden      

Chalk  soils: 
Wye     

Roxwell 

640  APPENDIX 

PHOSPHORUS  IN  SOILS  IN  THE  UNITED  KINGDOM  (Continued) 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6|  Inches  Deep) 


DESCRIPTION  AND  LOCALITY 
(Original  Sample  Nos.) 

PHOS- 
PHORUS 
(Lb.) 

DESCRIPTION  AND  LOCALITY 
(Original  Sample  Nos.) 

PHOS- 
PHORUS 
(Lb.) 

ENGLAND  (Continued) 

Kent  (continued) 
Minster,  Thanet  | 

Sutton-by-Dover     .... 
Meopham      

880 
820 

1670 
IIOO 

2130 
1320 

1690 

1570 

1540 

1890 
95° 

1150 
1190 

1160 

22IO 

73° 
420 

330 
1050 

1400 
1140 

1740 
1150 

Lincolnshire  (continued) 
Marsh  soil  (I)  

1400 
1830 

6710 
8890 
10800 
10500 

593° 
10700 

(II)  . 

Farm  near  Crowland   (I)    .     . 

(ii)  .  . 
(in)  .  . 

(IV)    .     . 
(V)    .     . 
(VI)    .    . 

Wye  Court  J     
Wye,  S.  E.  A.  C  

Olantierh  . 

Wye 

Norfolk 
Saxlingham  

720 
500 
1400 

Charing    

East  Lenham     

f 

Stanhoe   

Charing  j 

Trowse  plot      

1      
Gault  soils: 

n    ;  f  . 

Northampton 
Cransley  plot    (i)      .    .     .     . 

(2)        .... 

(3)      .-.. 
(4)      .... 
(5)      ..-. 
(6)      .... 
(7)      .... 
(8)      .... 
(9)      .... 
(10)      .... 

IOIO 

1260 
700 
1350 

I2IO 

1160 
1240 

990 
980 

1060 

Brook  | 

Westwell  |     

Charing    .     .     .     .     . 

East  Lenham     
f    . 

Brook  | 

East  Lenham     
Hothfield       

Northumberland 

Cockle  Park  (unmanured  plot) 
(i)    . 

960 

760 
1050 

Lincolnshire 
Peaty  matter  from  fens  .     .     . 
Fen  soil  (I)  

2180 

2270 
1830 
1400 

Miniature  Farms  (9)  .... 
(i)  .     .     .     . 

(II)  

(Ill)  

APPENDIX 


641 


PHOSPHORUS  IN  SOILS  m  THE  UNITED  KINGDOM  (Continued) 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6|  Inches  Deep) 


PHOS- 

PHOS- 

DESCRIPTION AND  LOCALITY 

DESCRIPTION  AND  LOCALITY 

(Original  Sample  Nos.) 

PHORUS 
(Lb.) 

(Original  Sample  Nos.) 

PHORUS 
(Lb.) 

ENGLAND  (Continued) 


Northumberland  (continued) 

Miniature  Farms  (2)  .     .     .     . 

(3)   •     •     •     • 
(4)   .... 

960 
1130 
1130 

Surrey 

Condon  clay: 
Wanborough  Station  . 
Ashtead  Common  .... 
Wyke  

57° 
810 
">^o 

(5)   •     •     •     • 

1130 

Flexford   

•580 

(6)   .    . 

1050 

46O 

Wanborough      

680 

Hanging  Leaves  (265)    .     .     . 
Castle  Steads  (267)    .... 

520 
610 

Raynes  Park      .     .          .     . 
Horsley          .         .... 

850 

IOIO 

Davy  Houses  (266)    .... 
East  Tower  Hill    .     .     .     .     . 

700 
14.80 

Chalk  soils: 

Pepnv 

?oo 

Scale    

IS7O 

Whitefield              

IOOO 

Fetcham  

1680 

Kirnblesworth  (^55)        •     • 

610 

Puttenham         

I4.CO 

1420 

PnrVlp  Part  • 

Sutton       

I2OO 

Tower  Hill    

ICKO 

800 

Back  House  

8^0 

650 

Tree  Field     .     .    .     .     .     . 

610 

Gault  soils,  Alder  Holt 

1320 

Pallace  Leas  Field-plot    (i)    . 

(2)      . 

(6)    . 
(8)    . 

(12)       . 

(13)  . 

Oxford 

870 
700 
520 
520 
520 
440 

Wiltshire 

Christchurch    Allotment    Sta- 
tion, Warminster     .     .     . 

Boreham  Road  I  '  •  ' 
Horningsham    

780 

2960 

2250 
262O 

22IO 

Heytesbury  

T.Q2O 

Wick.  Farm: 
Headington    (I)     .... 
(II)     .... 

Suffolk 

43° 
1050 

Codford  allotment  soil    .     .     . 
Chitterne  allotment  soils     .     . 

Imber  allotment  (i)  .     .     .     . 

(2)    .... 

Corslev  plot      

4060 
7920 

3230 
3510 

1  1  7O 

Bramford          

i  ^70 

Clay  soil,  Warminster     .     .     . 

222O 

2160 

York  warp  soil       

1940 

642 


APPENDIX 


PHOSPHORUS  IN  SOILS  IN  THE  UNITED  KINGDOM  (Continued) 
Pounds  per  Acre  in  2  Million  of  Soil  (about  6f  Inches  Deep) 


PHOS- 

PHOS- 

DESCRIPTION AND  LOCALITY 

PHORUS 

DESCRIPTION  AND  LOCALITY 

PHORUS 

(Lb.) 

(Lb.) 

SCOTLAND 


Lanark 

Cleghorn,  near  Lanark: 
Plot  i  

OIO 

Argyll 
Birgidale  Knock,  Rothesay 

2130 

Plot  2  .          .     . 

IIOO 

Aberdeen 

Tarves     

4IQO 

Dumbarton 

Wester  Fintray,  Kintore      .     . 
Fedderate,  Maud  

2470 
32OO 

Drumfork,  Helensburgh      .     . 
Nairn 
Easterboard,  Croy     .... 

3920 

II2O 

Tulloch,  Lumphanan     .     .     . 

Kincardine 
Fasque,  Fettercairn    .... 

990 
1870 

IRELAND 


Cork 

Wexford 

Limestone  soils,  Shanagany    . 
Old  red  sandstone,  Killeigh    . 

1290 
1360 

Silurian  clay  slate  soils: 
Bally-Carney     
Clonroche      

1360 
1460 

Tipperary 

Limestone  soils: 
Rockford       

1400 

St.  Kieran's  

1  1  -20 

WALES 


Garden  soil       

2670 

• 

AVERAGES  OF  ALL  SAMPLES 


England  (269  samples) 
Scotland  (10  samples) 
Ireland  (6  samples) 
Wales  (i  sample)    .     . 


2230 
2190 

1.33° 
2670 


APPENDIX 
SECTION    VII 


643 


AGRICULTURAL  COLLEGES  AND  EXPERIMENT  STATIONS  IN  THE  UNITED  STATES 

AND  CANADA 


STATE  OR 
TERRITORY 

NAME  OF  SCHOOL 

LOCATION  OP 
SCHOOL 

ADDRESS  OF 
AGRICULTURAL 
EXPERIMENT  STATION 

Alabama  .     .     . 

Alabama  Poly  technical 

Alabama         (College), 

Institute      .... 

Auburn 

Auburn 

Agricultural  School  of 

Alabama  (Canebrake), 

the  Tuskegee  Normal 

Uniontown 

and     Industrial    In- 

stitute      

Tuskegee  Institute 

Agricultural  and   Me- 

Alabama    (Tuskegee), 

chanical   College  for 

Tuskegee  Institute 

Negroes       .... 

Normal 

Alaska,  Sitka 

Arizona       .     .     . 

University  of  Arizona  . 

Tucson 

Arizona,  Tucson 

Arkansas    .     .     . 

Unversity  of  Arkansas  . 

Fayetteville 

Arkansas,  Fayetteville 

California   .    .     . 

Branch  Normal  College 
University  of  California 

Pine  Bluff 
Berkeley 

California,  Berkeley 

Colorado    .     .     . 

The  State  Agricultural 

Colorado,  Fort  Collins 

College  of    Colorado 

Fort  Collins 

Connecticut     .     . 

Connecticut     Agricul- 

Connecticut      (Storrs), 

tural  College    .     .     . 

Storrs 

Storrs 

Connecticut        (State), 

New  Haven 

Delaware   .     .     . 

Delaware  College   .     . 

Newark 

Delaware,  Newark 

State  College  for  Col- 

ored Students  .     .     . 

Dover 

Florida  .... 

University  of  the  State 

of  Florida   .... 

Gainesville 

Florida,  Gainesville 

Florida  State  Normal 

and  Industrial  School 

Tallahassee 

Georgia      .     .     . 

Georgia  State  College 

of  Agriculture  .     .     . 

Athens 

Georgia   State    Indus- 

trial College    .     .     . 

Savannah 

Georgia,  Experiment 

Hawaii 

College  of  Hawaii  .     . 

Honolulu 

Hawaii,  Honolulu 

Idaho 

University  of  Idaho    . 

Moscow 

Idaho,  Moscow 

Illinois 

University  of  Illinois  . 

Urbana 

Illinois,  Urbana 

Indiana 

Purdue  University  .     . 

Lafayette 

Indiana,  Lafayette 

Iowa 

Iowa  State  College  of 

Agriculture  and  Me- 

chanic Arts      .     .     . 

Ames 

Iowa,  Ames 

Kansas  .... 

Kansas  State  Agricul- 

tural College   .     .     . 

Manhattan 

Kansas,  Manhattan 

Kentucky  .     .     . 

State  University      .     . 

Lexington 

Kentucky,  Lexington 

The  Kentucky  Normal 

and  Industrial  Insti- 

tute for  Colored  Per- 

sons    

Frankfort 

Louisiana  .    .    . 

Louisiana    State    Uni- 

Louisiana          (State), 

versity  and   Agricul- 

Baton Rouge 

tural  and  Mechanical 

Louisiana  (Sugar),  New 

College  

Baton  Rouge 

Orleans 

Southern       University 

Louisiana  (North),  Cal- 

and  Agricultural  and 

houn 

Mechanical  College  . 

New  Orleans 

APPENDIX 


AGRICULTURAL  COLLEGE  AND  EXPERIMENT  STATIONS  IN  THE  UNITED  STATES 
AND  CANADA  (Continued) 


STATE  OR 
TERRITORY 

NAME  OF  SCHOOL 

LOCATION  OF 
SCHOOL 

ADDRESS  OF 
AGRICULTURAL 
EXPERIMENT  STATION 

Maine  .... 

The       University      of 
Maine     

Orono 

Maine,  Orono 

Maryland       .     . 

Massachusetts    . 

Michigan  .     .     . 
Minnesota 

Maryland  Agricultural 
College    
Princess    Anne    Acad- 
emy, Eastern  Branch 
of  the  Maryland  Agri- 
cultural College     .     . 
Massachusetts  Agricul- 
tural College    .     .     . 
Massachusetts  Institute 
of  Technology       .     . 
Michigan    State    Agri- 
cultural College    .     . 
The  University  of  Min- 
nesota      

College  Park 

Princess  Anne 
Amherst 
Boston 
East  Lansing 
Minneapolis 

Maryland,  College  Park 

Massachusetts,  Amherst 

Michigan,  East  Lansing 
Minnesota,  St.  Anthony 
Park,  St.  Paul 

Mississippi     .     . 
Missouri    .     .     . 

Mississippi       Agricul- 
tural and  Mechanical 
College   
Alcorn  Agricultural  and 
Mechanical  College  . 
College  of  Agriculture 
and  Mechanic  Arts  of 
the  University  of  Mis- 
souri    

Agricultural  College 
Alcorn 

Columbia 

Mississippi,       Agricul- 
tural College 

Missouri  (College),  Co- 
lumbia 
Missouri  (Fruit),  Moun- 
tain Grove 

School   of   Mines   and 
Metallurgy     of     the 
University    of     Mis- 
souri   

Rolla 

Montana  . 

Lincoln  Institute    .     . 
Montana   Agricultural 
College  

Jefferson 
Bozeman 

Montana,  Bozeman 

Nebraska       .     . 

Industrial    College    of 
the  University  of  Ne- 
braska      

Lincoln 

Nebraska,  Lincoln 

Nevada     .     .     . 
New  Hampshire 

University  of  Nevada  . 
New   Hampshire   Col- 
lege   of    Agriculture 
and     the     Mechanic 
Arts    

Reno 
Durham 

Nevada,  Reno 

New  Hampshire,  Dur- 
ham 

New  Jersey   .     . 

New  Mexico 
New  York 

Rutgers           Scientific 
School     (The     New 
Jersey  State  College 
for     the    Benefit    of 
Agriculture   and   the 
Mechanic  Arts)    .     . 
New  Mexico  College  of 
Agriculture  and  Me- 
chanic Arts       .     .     . 
New  York  State  College 
of  Agriculture  at  Cor- 
nell University      .     . 

New  Brunswick 
Agricultural  College 
Ithaca 

New  Jersey,  New  Bruns- 
wick 
New   Mexico,   Agricul- 
tural College 

New    York    (Cornell), 
Ithaca 
New  York  (State),  Ge- 
neva 

APPENDIX 


645 


AGRICULTURAL  COLLEGES  AND  EXPERIMENT  STATIONS  IN  THE  UNITED  STATES 
AND  CANADA  (Continued) 


STATE  OR 
TERRITORY 

NAME  OF  SCHOOL 

LOCATION  or 
SCHOOL 

ADDRESS  OF 
AGRICULTURAL 
EXPERIMENT  STATION 

North  Carolina  . 

The    North    Carolina 

North    Carolina    (Col- 

College of  Agriculture 
and  Mechanic  Arts   . 
The   Agricultural   and 

West  Raleigh 

lege),  West  Raleigh 
North  Carolina  (State), 
Raleigh 

Mechanical     College 

for  the  Colored  Race 

Greensboro 

North  Dakota    . 

North  Dakota  Agricul- 

North Dakota,  Agricul- 

tural College    .     .     . 

Agricultural  College 

tural  College 

Ohio     .... 

Ohio  State  University  . 

Columbus 

Ohio,  Wooster. 

Oklahoma.     .     . 

Oklahoma  Agricultural 

and  Mechanical  Col- 

Stillwater 

Oklahoma  Stillwater 

Agricultural  and  Nor- 

mal University  .     .     . 

Langston 

Oregon      .     .     . 

Oregon  State  Agricul- 

tural College    .     .     . 

Corvallis 

Oregon,  Corvallis 

Pennsylvania 

The  Pennsylvania  State 

Pennsylvania,  State  Col- 

College    

State  College 

lege 

Porto  Rico     .     . 

University  of  Porto  Rico 

San  Juan 

Porto  Rico,  Mayaguez 

Rhode  Island     . 

Rhode    Island  College 

of    Agriculture    and 

Mechanic  Arts      .     . 

Kingston 

Rhode  Island,  Kingston 

South  Carolina  . 

The  Clemson  Agricul- 

tural College  of  South 

Clemson  College 

South   Carolina,   Clem- 

The Colored  Normal, 

son  College 

Industrial,     Agricul- 

tural, and   Mechani- 

cal College  of  South 

Carolina      .... 

Orangeburg 

South  Dakota    . 

South     Dakota    State 

• 

College    of    Agricul- 

ture   and    Mechanic 

South  Dakota,    Brook- 

Arts  

Brookings 

ings 

Tennessee      .     . 

University  of  Tennessee 

Knoxville 

Tennessee,  Knoxville 

Texas  .... 

Agricultural    and  Me- 

chanical   College    of 

Texas     

College  Station 

Texas,  College  Station 

Prairie  View  State  Nor- 

mal   and    Industrial 

College   

Prairie  View 

Utah      .     .     .     . 

The  Agricultural   Col- 

lege of  Utah    .     .     . 

Logan 

Utah,  Logan 

Vermont    .     .     . 

University  of  Vermont 

and    State     Agricul- 

tural College    .     .     . 

Burlington 

Vermont,  Burlington 

Virginia     .     .     . 

The  Virginia  Agricul- 

tural and  Mechanical 

College  and  Polytech- 

Virginia          (College), 

nic  Institute     .     .     . 

Blacksburg 

Blacksburg 

The  Hampton  Normal 

Virginia  (Truck),  Nor- 

and Agricultural  In- 

folk 

stitute     

Hampton 

646 


APPENDIX 


AGRICULTURAL  COLLEGES  AND  EXPERIMENT  STATIONS  m  THE  UNITED  STATES 
AND  CANADA  (Continued) 


STATE  OR 
PROVINCES 

NAME  OF  SCHOOL 

LOCATION  OF 
SCHOOL 

ADDRESS  OF 
AGRICULTURAL 
EXPERIMENT  STATION 

Washington    .     . 

State  College  of  Wash- 

ington     

Pullman 

Washington,  Pullman 

West  Virginia 

West  Virginia  Univer- 

West Virginia,  Morgan- 

sity    

Morgantown 

town 

The  West  Virginia  Col- 

ored Institute  .     .     . 

Institute 

Wisconsin  .    .     . 

University  of  Wisconsin 

Madison 

Wisconsin,  Madison 

Wyoming   .     .     . 
Alberta  .... 

University  of  Wyoming 
University  of  Alberta  . 

Laramie 
Edmonton 

Wyoming,  Laramie 
Alberta       (Provincial), 

Edmonton 

(Dominion),  Lacombe 

(Dominion),        Leth- 

bridge 

British  Columbia 

(Dominion),  Agassiz 

Manitoba   .     .    . 

Manitoba  Agricultural 

Manitoba 

College  

Winnipeg 

(Dominion),  Brandon 

(Provincial),    Winne- 

Peg 

Nova  Scotia    .     . 

Nova    Scotia  Agricul- 

Nova Scotia 

tural  College  .     .     . 

Truro 

(Dominion),  Nappan 

(Provincial),  Truro 

Ontario  .... 

Ontario        Agricultu- 

Ontario 

ral  College    .      .    . 

Guelph 

(Provincial),  Guelph 

(Dominion      central), 

Ottawa 

Prince  Edward  Island 

(Dominion),       Char- 

lottetown 

Quebec  .... 

MacDonald    Agricul- 

tural College  .    .    . 

St.  Anne 

Quebec 

(College),  St.  Anne 

Saskatchewan 

University     of      Sas- 

Saskatchewan 

katchewan      .    .     . 

Saskatoon 

(Dominion),     Indian 

Head 

(Dominion),  Rosthern 

(Provincial),     Saska- 

toon 

INDEX 


Abandoned  lands : 

eastern  United  States,  342,  591 
Maryland,  140 
Rothamsted,  403 
Acid,  defined,  20 
Acid  phosphate,  189 
Acid  salts,  23 
Acidity  of  soils,  163,  566 
determination,  627 
test,  566 

Acids,  common,  24 
Adobe  soil,  65 
African  soils,  66 
Agdell  field,  Rothamsted,  345 
Agricultural  colleges  in  the  United  States 

and  Canada,  643 
established  by  law,  518 
Agricultural    experiment    stations    in    the 

United  States  and  Canada,  643 
established  by  law,  505,  518 
Agricultural  history,  two  periods,  590 
Agriculture,  permanent  systems,  159 
Aikman,  early  use  of  bones,  324 
Air,  composition,  13 
Alabama,  field  experiments,  494 

soils,  138 
Albite,  47 
Aldehydes,  30 
Alkali,  defined,  20 
Alkali   salt,   fertilizer  or  stimulant,   364, 

393,  402,  479,  533 
Allyl,  40 
Aluminum,  44 

American  agricultural  colleges  and  experi- 
ment stations,  643 
Amids  and  amido  group,  37 
Ammonification,  195 
Ammonium  sulfate,  525 
Analysis  of  animal   and   plant   products, 

157,  602 

Analysis  of  soils,  626 
Analyzing,  and  testing  soils,  565,  626 
Animal  and  plant  products,  composition, 

157,  602 
Animal  fats,  35 


Animals  destroy  organic  matter,  199 

Anorthite,  47 

Appearance  of  soils  and  crops  in  relation 

to  fertility,  572 
Arid  and  semiarid  sections,  rainfall  records, 

580,  582 

Arid  soils,  126,  129,  139 
Arkansas  soils,  97 
Asbestos,  49 
Ashes,  composition,  602 

fertility  experiments,  508,  511 
Asiatic  soils,  66,  67 
Association,  National  Fertilizer,  report  on 

raw  phosphate,  292 
Atom,  defined,  3 
Atomic  bond,  4 
Atomic  weight,  defined,  3 
Atomic  weights,  table,  10 
Available  plant  food,  107,  314,  366 

Bacteria : 

denitrifying,  439 

nitrifying,  195 

nitrogen-fixing,  207 

nonsymbiotic,  or  "free-living,"  225,  437 
Barley: 

Canadian  experiments,  505 

composition,  603 

Rothamsted  experiments,  378 

statistics,  616 

Barn  field,  Rothamsted,  398 
Barren  soils,  63,  367 
Base,  defined,  20 
Basic  slag  phosphate,  192 
Beans,  composition,  417,  603 
•  fertility  loss,  550 
Bond,  atomic,  4 
Bone  meal,  157,  185 

Bones  and  other  phosphates  used  in  Eu- 
rope, 324 

Bottom  land  soils,  62,  120,  138 
Bradley's  soil  fertility  theories,  300 
Bran,  wheat,  composition,  41,  604 
Breathing  pores,  29 
Broadbalk  field,  Rothamsted,  363 
647 


648 


INDEX 


Bulbs,  composition,  604 
Bureau  of  Soils,  United  States  Department 
of  Agriculture: 

pot  cultures,  513 

soil  analyses,  136 

soil  fertility  theories,  313,  362,  367 

soil  surveys,  114 
Butter,  composition,  154 

statistics,  623 

Cabbage,  composition,  604 

experiments,  266,  278 
Cake,  oil,  composition,  604 

fertility  loss,  205 

statistics,  626 
Calcium,  43 
Calcium  cyanamid,  526 
Calcium  determination,  632 
Calcium  nitrate,  526 
California  soils,  102,  138 
Canadian  colleges  of  agriculture,  646 

experiment  stations,  505,  646 

field  experiments,  505 

soils,  103,  507,  559 
Carbohydrates,  30 
Carbon,  26 
Carbon  cycle,  32 

determination,  628 

fixation,  29  , 

supply  as  plant  food,  33 
Carbonates,  50 

determination,  628 

loss  by  leaching,  51,  174 

test,  567 
Carrots,  composition,  604 

field  experiments,  511 
Casein,  41 

Central  states  soils,  77,  138 
Cereal  seeds,  composition,  154,  603 
Chaff,  composition,  603 
Chemical  action,  3,  107,  194,  562 
Chemical  elements,  10 
Chemistry,  defined,  i 

organic,  30 

China,  agricultural  conditions  and  prac- 
tices, 335 

Chinese  philosophy,  594 
Chlorin,  44 
Chlorophyll,  43 

Clarke,  on  composition  of  earth's  crust,  13 
Clay,  50,  55 

Clover,  composition,  75,  154,  417,  603 
Clover  sickness,  312,  406 
Coal  ashes,  composition,  602 
Coastal  plains  soils,  117,  138,  139 
Cobs,  corn,  composition,  603 
Colleges  of  agriculture,  518,  643 
Colorado  soils,  101 


Combining  weights  of  elements,  3 
Commercial  fertilizers,  517 
Commercial  plant  food  materials,  157 
Common  elements,  13 
Common  functions  of  elements,  45 
Composition  of  animal  and  plant  products, 

157,  602 

Compound,  defined,  2 
Connecticut,  investigations  with  legumes, 
219 

soil,  138 
Corn,  composition,  13,  75,  154,  603 

cost  per  bushel,  585 

record  yield,  619 

statistics,  606 

Corn  cobs,  composition,  603 
Cotton,  composition,  154,  497,  603 

statistics,  624 
Cotton  seed,  154,  525,  603 
Cotton-seed  meal,  525,  604 
Condition  of  soil,  576 
Conservation  of  soil  moisture,  577 
Coral  limestone  soil,  65 
Creelman,  on  farming  in  Southern  Europe, 

329 

Crimson  clover  tops  and  roots,  composi- 
tion, 221 

Critical  periods  in  plant  life,  538 
Crop  residues,  199 
statistics,  605 
stimulants,  533 
yields  (see  also  statistics): 
Asia,  334 
Europe,  326 
Kansas,  330 
Crops,  composition,  botanical,  393 

chemical,  154,  417,  418,  602 
Crysolite,  47 
Curie  and  Gleditsch,  on  transmutation  of 

elements,  n 
Cyanamid,  526 
Czapek,  on  availability  of  plant  food,  109 

Decandolle's  soil-fertility  theories,  310 

Decay  of  organic  matter,  195 

Delaware     investigations      with     legume 

plants,  221,  222 
Denmark,  wheat  yield,  614 
Dentrification,  439,  502 
De  Saussure's  discovery  of  mineral  plant 

food,  307 
Digestion  coefficients  for  organic  matter, 

199,  206 

Dolomitic  limestone,  169 
Drainage    reclamation     possible    in     the 

United  States,  583 
Dry  farming,  579,  581 
Dyer,  on  manure  used  in  England,  324 


INDEX 


649 


Earth's  crust,  13,  46 

Eastern  states  soils,  72,  75,  138 

Element    system    for   reporting    analyses, 

S^S.  599 
Elements  in  air,  ocean,  and  earth's  crust, 

i3 

of  plant  growth,  12 
the  more  common,  13 
transmutation,  n 
English  soils,  637 
Equilibrium  in  nature,  62 
Essential  elements  of  plant  food,  12 
European  crop  yields  (see  also  statistics), 

326 

European  soils,  634 
Experiment  stations  in  the  United  States 

and  Canada,  643 
established  by  law,  505,  518 

Factors  in  crop  production,  435,  575 
Famines,  Indian,  334 

Russian,  333 
Farm  manure,  composition,  542 

Cambridge  University  investigation,  205 

Canadian  experiments,  508,  511 

dried,  545 

English  practice,  324 

Illinois  experiments,  201,  206,  459,  473, 
480 

Japan,  human  and  compost,  594 

Ohio  experiments,  204,  256,  442,  448, 

547 

Pennsylvania  experiments,  202,423,431 

Rothamsted  experiments,  364,  380,  390, 

393.  399t  4oo,  407,  4" 
Fats,  34 
Felspars,  47 

Fertility  theories,  300,  362,  366,  385,  389 
Fertilizer    Association's    report    on    raw 

phosphate,  292 
Fertilizer  law,  599 
Fertilizers,  commercial,  157,  517 
Fish-scrap  fertilizer,  525 
Fixation  of  plant  food  by  soils,  562 

of  carbon,  oxygen,  and  hydrogen,  29 

of  free  nitrogen,  207,  225,  437 
Flax,  composition,  603,  604 

sickness,  319 

statistics,  605 
Florida  phosphates,  187,  188,  595 

sand  and  peat  soils,  498 
Formula,  chemical,  defined,  7 
France,   crop  yields   (see  also  statistics), 

327 

soils,  635 

Fruits,  composition,  604 
Functions  that  are  common  to  different 

elements,  45 


Gas  law,  7 

Georgia,  field  experiments,  489 

soils,  94 

Germany,  crop  yields  (see  also  statistics), 
326 

soils,  634 

Glacial  material,  54 
Glacial  soils,  123,  138,  144 
Glycerin,  40 
Gneiss,  48 
Grain  farming,   226,   329,  345,  434,  459, 

478,  483 
Granite,  48 
Graphite,  26 
Grass,  composition,  603 

digestibility,  199 
Green  manuring,  199,  218 
Ground  limestone  and  burned  lime,  165 
Growth  of  plants,  32 

Hall,  on    soil-fertility  theories,   319,   362, 

366,  385 

Hay,  composition,  75,  154,  417,  418,  603 
Hay  grown  every  year,  Rothamsted,  391 
Hay  statistics,  605,  624 
Heat  factor  in  crop  production,  576 
Hellriegel's    discovery    of    nitrogen-fixing 

bacteria,  307 

Hill's  view  of  agriculture,  594 
History  of  agriculture,  590 
Holland,  soil,  63 

wheat  yield,  614 
Home  of  plants,  576 
Hoos  field,  Rothamsted,  378 
Hops,  composition,  604 
Hornblende,  49 

Hunter's  soil-fertility  theories,  302 
Hydrate,  defined,  28 
Hydrogen,  28 
Hydroxid,  defined,  17 

Idaho,  phosphates,  595 

soils,  102 
Illinois,  field  experiments,  283,  453,  476 

pot-culture  experiments,   171,  287,  486, 
487 

soils,  82,  138 
India,  agricultural  conditions,  333 

soils,  66 

Indiana  soils,  88 

Inoculation  for  nitrogen  fixation,  211 
Intermountain  soils,  127 
Iowa,  field  experiments,  488 

soils,  89 

Ireland,  soils,  642 
Iron,  43,  69,  73,  75,  106,  603 
Iron  sulfate  as  a  fertilizer,  158,  505 
Italian  agriculture,  329 


650 


INDEX 


Irrigation,  in  India,  333,  583 

possible  in  the  United  States,  583 

Japan,  agricultural  practices,  594 
Jethro  Tull's  soil-fertility  theories,  300 

Kainit,  530,  535 

Kansas,  crop  yields  (see  also  statistics),  330 

soils,  138 
Kentucky,  pot-culture  experiments,  288 

soils,  64,  65,  92,  138 
King,  on  Japanese  agriculture,  594 

on  water-soluble  plant  food,  142 
Kossowitsch,  availability  of  raw  phosphate, 
109 

Land-plaster,  256,  420,  505,  533 

Land  reclamation  possible  in  United  States, 

583 

Land  values,  586 
Law,  constant  proportions,  8 

diminishing  returns,  374 

gas,  7 

governing  sale  of  fertilizers,  599 

periodic,  9 

solution,  314,  316,  366 
Lawes  and  Gilbert,  source  of  nitrogen  for 

plants,  307 
Leaching,  rocks,  soils,  49,  51,  174,  413,  556 

plants,  549 
Lecithin,  40 
Legume  plants,  composition,  154,  218,  604 

inoculation,  210,  218 

nitrogen  fixation,  207 

tops  and  roots,  218 
Legume  seeds,  composition,  154,  603 
Liberation  of  plant  food,  109 
Liebig's  soil-fertility  theories,  308 
Liebig's  view  of  agriculture,  591 
Life,  29 

Life  of  soil,  195 

Light  factor  in  crop  production,  576 
Lime  and  ground  limestone,  165 
Lime  burning,  27 
Limestone,  amount  to  apply,  172 

how  to  apply,  179 

loss  by  leaching,  51,  174,  561 

magnesian,  or  dolomitic,  169 

soils,  123,  147 

spreader,  179 

time  to  apply,  178 

use  in  soil  improvement,  160 
Limiting  factors  in  crop  production,  435, 

575  _ 

Lincoln's  view  of  agriculture,  592 
Lipman,  on  dentrification,  439 
Live  stock  destroy  food  values,  234 

organic  matter,  199 
Live-stock  farming,  231,  459 


Loess,  characteristics,  54 

composition,  69 

in  United  States,  68 
Loessial  soils,  123,  144,  634 
Losses  of  plant  food,  from  manure,  200, 
546,  547 

from  plants,  549 

from  soils,  411,  413,  556 
Louisiana,  field  experiments,  495 

soils,  96,  138 

Machine    for    spreading    limestone    and 

phosphate,  179 
Magnesian  limestone,  169 
Magnesium,  42 
Magnesium  determination,  633 

in  fertilizer  experiments,  171,  364 
Maine  field  experiments,  275 
Maintenance  rations,  33 
Manganese,  44 
Manganese  separation,  633 
Mangel-wurzel,  composition,  402 

field  experiments,  400 
Mann,  on  the  use  of  raw  phosphate,  504 
Manure,  losses  from  exposure,  200,  256, 
508,  546,  547 

preservatives  and  reenforcing  materials, 

256,  547  _ 

recovered  in  live-stock  farming,  201 
Manure  in  culture  experiments,  256,  343 
Manures    (see    farm   manure   and   green 

manuring) 

Marl  carbonates,  167 
Marl  phosphates,  241 
Maryland,  field  experiments,  261 

soils,  138,  141 

subsoils,  73 

Massachusetts  field  experiments,  278 
Mellilotus  for  green  manuring,  220 
Mica,  49 

Michigan,    investigations     with     legume 
plants,  216,  221 

soils,  97 
Minnesota,  soil  experiments,  499 

soils,  100,  138 
Mississippi  soils,  93 
Missouri  soils,  89,  138 
Moisture  factor  in  crop  production,  577 
Molecule,  defined,  4 
Montana  soils,  102 
Mountain  soils,  122,  128 

Nascent,  defined,  4 

National  Fertilizer  Association  report  on 

raw  phosphate,  292 
Nebraska  rainfall,  331,  580,  582 

soils,  89 
Nevada  soils,  102 


INDEX 


651 


New  Jersey,  pot-culture  experiments,  439 

soil,  138 

New  York,  investigation  of  phosphorus  in 
wheat  bran,  41 

soils,  75 

Nitrate  of  calcium,  526 
Nitrate  of  sodium,  525 
Nitrification,  195 
Nitrogen,  36 

Nitrogen  and  organic  matter,  194 
Nitrogen  determination,  629 

fixation  by  legumes,  207 

by   nonsymbiotic   bacteria,  224,  405, 

437 

from  air  and  soil,  213 

gain  or  loss  difficult  to  determine,  499 

in  animal  and  plant  products,  154,  602 

in  drainage  waters,  557,  563 

in  fertilizers,  157,  517 

in  rain,  309 

in  roots  and  tops  of  legumes,  218 

in  sweet  clover,  220 

recovered  in  live-stock  farming,  201 

retained  by  animals,  201 

used  in  different  amounts,  374,  423 

used  to  give  crops  a  start,  218,  401,  533 
Nitrogenous  compounds,  38 
Nomenclature,  19,  565,  599 
North  Carolina  soils,  138,  142 
North  Dakota  investigations  of  flax  sick- 
ness, 319 

North  Platte,  Nebraska,  rainfall,  331,  580 
Northern  states  soils,  97,  138 
Nuclein,  40 

Oats,  composition,  75,  154,  603 

statistics,  615 
Ocean,  composition,  13 
Ohio,  field  experiments,  245,  299,  441 

investigations  with  manure,  547 

soils,  88,  138 

in  pot-culture  experiments,  513 
Oil  cakes,  composition,  604 

fertility  loss,  205 

statistics,  626 

Oil  seeds,  composition,  603 
Oils  and  fats,  34 
Oregon  soils,  102 
Organic  chemistry,  30 
Organic  matter,  defined,  30 

decomposition,  195 

loss  in  digestion,  199 

methods  of  supplying,  198 
Organic  matter  and  nitrogen,  194 
Orthoclase,  47 
Oxids,  defined,  17 

occurrence,  53 
Oxygen,  26 


Pacific  coast  soils,  102,  130,  138 

Park  field,  Rothamsted,  391 

"Parrot"  instruction,  292 

Pasturing  land,  199 

Peat,  dried,  524 

Peat  soils,  75,  83,  98,  100,  470 

Pennsylvania,  field  experiments,  263,  420 

investigations  with  manure,  202,  203 

soils,  76,  142 
Pentosans,  31 

Periodic  law  of  chemical  elements,  9 
Permanent  systems  of  agriculture,  159 
Peter,  on  soil  fertility  theories,  339 
Phosphate  deposits,  597 
Phosphate  experiments: 

Canada,  505 

Illinois,  283,  504 

Indiana,  296 

Kentucky,  288 

Maine,  275 

Maryland,  261 

Massachusetts,  278 

Ohio,  245,  442,  448,  452 

Pennsylvania,  263 

Rhode  Island,  266 
Phosphate  production,  595 

raw  rock  and  slag  must  be  fine-ground, 

239 

in  practical  agriculture,  289,  504 
Phosphate   report   by   National   Fertilizer 
Association,  292 

spreader,  179 

supply,  597 
Phosphates,  52,  186 

low-grade,  188,  242,  598 

natural,  52,  186 

used  in  Europe,  324 
Phosphatic  limestone,  52 

marl,  241 

slag,  192 

Phosphorus,  40,  52,  183,  236 
Phosphorus  compounds,  189 

determination,  630 
'in  fertilizers,  157,  517 

in  plant  and  animal  products,  154,  602 

in  wheat  bran,  41 

production,  595 

retained  by  animals,  201 

supply,  597 

use  in  different  forms,  237 

used  in  Europe,  324 
Photosynthesis,  29 
Physical  condition  of  soil,  576 
Piedmont  soils,  121,  138 
Plant  and  animal  products,  composition, 

157,  602 
Plant  food,  26 

available,  107,  314,  366 


652 


INDEX 


Plant  food,  essential,  12 

in  crops,  75,  154,  602 

in  culture  experiments,  236,  343 

in  sea  weed,  524 

lost  from  manure,  200,  546,  547 
from  plants,  549 
from  soils,  411,  413,  418,  556 
Plant  food,  recovered  in  live-stock  farm- 
ing, 199 

retained  by  animals,  201 

sources  and  cost,  commercially,  157,  517 

value,  154 

water-soluble,  141 

Plot  experiments  for  testing  soils,  569,  570 
Potassium,  42 

Potassium  chlorid  and  sulfate,  531 
Potassium  determination,  631 
Potassium,  from  sea  water,  531 

in  fertilizers,  157,  517 

in  plant  and  animal  products,  154,  602 
Potassium  salts  of  Germany,  529 
Potato  experiments,  384,  447,  511 
Potatoes,  composition,  154,  604 

statistics,  605,  618 
Prairie  soils,  78,  82,  132,  138 
Prefixes  in  chemical  names,  19 
Proportions,  law  of  constant,  8 
Protective  agents,  536 
Protein  and  proteids,  37 

Quartz,  49 

Radicle,  denned,  17 

Rain,  composition,  309 

Rainfall  and  drainage  records,  309,  377, 
413,  491,  557,  580,  582 

Rainfall  averages  for  the  United  States, 
582 

Rainfall  in  dry  farming  sections,  580,  582 

Ramsay,  on  composition  of  air,  13 

Ramsay  and  Cameron,  on  transmutation 
of  elements,  n 

Rate  of  growth,  32 

Residual  soils,  54,  126,  146,  149 

Residues  of  crops  used  in  soil  improve- 
ment, 199 

Rhode  Island  field  experiments,  266 

Rice,  composition,  603 
statistics,  619 

Rock  weathering,  49 

Roman  agriculture,  590 

Root  crops,  compositidn,  417,  604 
in  Canadian  experiments,  511 
in  Rothamsted  experiments,  398 

Roots  and  tops  of  legumes,  composition, 
218 

Root  tubercles,  composition,  215 
size,  213 


Rotation  crops  grown  in  experiments: 

Agdell  field,  Rothamsted,  345 

Illinois,  453 

Louisiana,  495 

Minnesota,  499 

Ohio,  245,  256,  441 

Pennsylvania,  421 

Rotation  crops,  plant  food  required,  75 
Rotation  of  crops  and  soil  fertility,  318. 

339,  362,  389,  435,  443 
Rotation  systems,  226,  231 
Russia,  agricultural  conditions,  332 

soils,  66 
Rye,  composition,  603 

statistics,  617 

Sachs,  on  availability  of  plant  food,  109 
Salt,  common,  535 

defined,  20 
Salt  deposits,  53,  529 
Sand  soils,  80,  98,  100,  138,  468,  498 
Science,  defined,  i 
Scotland,  soils,  63,  642 
Seed  factor  in  crop  production,  575 
Semiarid  section,  rainfall  records,  331,  580, 

582 
S6nebier's    discovery   of    carbon    fixation, 

307 

Shale,  50 

Shutt,  on  loss  of  organic  matter  and  nitro- 
gen, 200,  559 

Silicates  in  earth's  crust,  47,  48 
Silicon,  44,  46 
Slag  phosphate,  192 
Snow,  composition,  310 
Soaps,  36 
Sodium,  44 
Sodium  in  fertilizer  experiments,  364,  380, 

402,  508 
Soil  analysis,  methods,  626 

classification,  54,  116 

composition,  58,  138 

depletion,  556 

by  natural  agencies,  61 
Soil  fertility  theories,  300,  362,  366,  385 

formation,  54 

materials,  55 

provinces  of  the  United  States,  116 

samples,  method  of  collecting,  626 

series,  116,  132 

stimulants,  45,  158,  533 

structure,  116 

surveys,  57,  77,  114,  5^7,  555 

texture,  116 

types,  55 
Soils  of  Africa,  66,  67 

Canada,  103 

central  states,  77,  138 


INDEX 


653 


Soils  of  eastern  states,  72,  75,  106,  138 

Europe,  63,  634 

India,  66 

Northern  states,  97,  138 

Rothamsted,  63,  411,  416 

Russia,  66 

South  America,  67 

southern  states,  92,  138 

Transvaal,  67 

Turkey,  67 

western  states,  101,  138 
Solution  law,  314,  316,  366 
South  American  soil,  67 
South  Carolina,  phosphates,  187,  595 

record  yield  of  corn  per  acre,  619 
Southern  states  soils,  92,  138 
Spencer,  on  farming  in  semiarid  region, 

58i 

Spillman,  on  Kansas  crop  yields,  330 
Spreader  for  limestone  and  phosphate,  179 
Starches,  31 

Statistics  of  agricultural  products,  605 
Steatite,  48 
Sterile  soils,  63,  367 

Stimulants,  368,  394,  402,  479.  5°8,  533 
Straw,  composition,  157,  603 
Structure  of  soils,  116 
Success  in  farming,  584 
Sugar  beets,  155,  399,  604 
Sugar  statistics,  620 
Sugars,  31 

Sulfates  and  sulfids,  52 
Sulfur,  39,  57,  106,  158 

in  rain,  106 
Superphosphate,  191 
Supply  and  demand  of  plant  food,  59 
Swamp  soils,  80,  583 

Sweet  clover,  content  of  nitrogen  and  or- 
ganic matter,  220 
Symbol,  denned,  7 
Systems  of  permanent  agriculture,  159 

Temperature   factor  in   crop   production, 

576 
Tennessee,  phosphates,  187,  188,  595 

soils,  64,  93,  138,  367 
Terminations  in  chemical  names,  19 
Terrace  soils,  124 
Testing  soils,  565,  626 
Texas  soils,  95,  138 
Texture  of  soils,  116 
Timer's  soil-fertility  theories,  302 
Theories  concerning  soil  fertility,  300,  362, 

366,  385 

Timber  soils,  79,  133 
Tobacco,  composition,  604 

experiments,  288 

statistics,  605 


Transmutation  of  elements,  n 
Transported  soils,  54 
Transvaal  soils,  67 

Tubercles  on  roots  of  legumes,  212,  215 
Tubers,  composition,  604 
Tull's  soil-fertility  theories,  300 
Turkish  soil,  67 
Turnips,  composition,  417,  604 
experiments,  346,  399 

Utah,  phosphates,  596 
soils,  101 

Valence,  defined,  4 

Value  of  land,  586 

Van  Helmont's  soil-fertility  theories,  300 

Van  Hise,  on  phosphates,  560 

Vegetable  fats  and  oils,  34 

Vegetables,  composition,  604 

Vesuvius  lava,  composition,  67 

Virginia,  field  results  with  raw  phosphate, 

289 

soil,  138 

Vital  processes  in  plant  growth,  33 
Volcanic  ash,  67,  138 

Wales  soil,  642 
Washington  soils,  102 
Water  (see  moisture) 
Water-soluble  plant  food,  141,  513 
Weathering  of  rocks  and  soils,  49,  61,  174 
Webster's  view  of-  agriculture,  594 
Western  states  soils,  101,  138 
Wheat,  composition,  75,  154,  417,  603 
Wheat  bran,  composition,  41,  604 
Wheat  grown  every  year: 

Canada,  505 

Jethro  Tull,  306 

Minnesota,  499 

Rothamsted,  363 

Whitney,  on  potatoes  at  Rothamsted,  389 
Whitney  and  Cameron's  soil-fertility  theo- 
ries, 313,  362,  367,  385 
Whitson,  on  loss  of  phosphorus  from  Wis- 
consin soils,  560 

Widtsoe,  on  arid  soils  and  vegetation,  101 
Williams,  on  value  of  manure  in  China,  338 
Wilson,  on  abandoned  lands,  342 
Wing,  on  use  of  limestone  and  raw  phos- 
phate, 289 
Wisconsin  experiments,  216,  221,  289,  560 

soils,  99,  138 
Wood  ashes,  531,  602 
Wyoming  phosphates,  595 

soils,  102 

Zein,  39 
Zeolites,  50 


This  book  is  DUE  on  the  last  date  stamped  below 


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